I'm looking to buy a new A/C set up for my car. I was wondering if they have come a long way compared to my 27 year old original. Also where can I buy one. I own a 1986 Cougar with a 5.0 HO engine. Thanks!
not sure if you got a quote yet or not, im not really sure where to point you. your stock compressor is really over built, one thing of many ford did imho.
are you thinking the compressor is burned up? or is it just the clutch that is not kicking in?
sorry, thought i saw on your other hvac post that you mentioned it was cooling nice and good.
Jay i thought the AC system was up and running . Has things changed???? The ford system is quite adequate and has a rating somewhere around 3 1/4 TUNS. Bigger than most other cars on the road. And the compressors on these cars are one of the best on the market. What would be accomplished with a vintage air swap. I use Vintage all the time in cars that do not have AC. But what would someone with a sytem that is supposedly working want to rip out a perfectly good working system. I am lost for thoughts on this one!!!!!!!!!!!!
Mechanical things like pumps haven't really changed. If you're looking for the best of everything, I can recommend the 97 Cobra condenser. I have my A/C system setup to provide continuous vent temperatures in the upper 30's during the hottest days when on the highway. The vent temperature is in the upper 40's when sitting in stop and go traffic as the compressor isn't compressing the refrigerant quick enough and there isn't the large amounts of airflow over the condenser. In cooler temperatures, the compressor cycles a bit since the entire system is borderline low on refrigerant, but I set it up for the coolest temperatures on the hottest days and I didn't care about it as much when under 80F. I think I set it up with a charge to get me 22-24F at the evaporator, which just barely does NOT freeze over. I don't think you can get a cooler A/C system than this. When I first did it, I was so excited that I kept it on max all the time, with the vents blowing at me. Once I got out of the car after a 40 minute highway drive, on a 90+F day, I found that the skin on my right hand was cold enough to stay chilled outdoors for a few minutes before it warmed back up.
This was with a new compressor (old one was dead after sitting "not working" for a decade) and conversion to r134 refrigerant/oil. I don't remember the site I got the parts off of as it has been years. It was some A/C specific website that provides everything for the conversion. I purchased new liquid and gas lines also, along with a new accumulator.
Our systems can work great. I enjoy the r134 conversion after a condenser swap. Of course the oil isn't compatible between r134 and r12, so you'd want to flush everything out the best you can.
Normally the AC systems today use electric fans to keep air flow over the condenser stable in traffic. And normally the compressor pulley size was changed a bit when RA134A came on the scene with the engine in traffic. Condenser size is critical on 134A but if you look at the tables the two freons are almost exactly the same performance wise. But i am going on record and saying the ford compressor on these cars are well able to handle any AC requirements one might encounter. The double air system on stretched limos use the same compressor. As the matter of fact ford has a bigger compressor for like SCHOOL BUSES with double air but they are not necessary. Also his car is a CCOT and that in itself is a high performance unit. Just a question SEEK how do you keep evaporator freezing up with 22-24* evaporator temps??? I am puzzled at how you accomplish that. And how do you get those temps when the stock setup kicks at 32 LBS Gauge??? (low side)
i did some web crawling , there seems to be several options out there for aftermarket HVAC support in cars.
I would not know the differences in choices though, would have to do some reading and asking around.
post up some pics of your new system when you get it in, this may become a necessary evil for all of us one day and the data would be important.
Actually guys, it was just a question. The A/C system on my car is all original and I was just wondering if it decides to die on me, I want to know what to look for. I just came back from a 260 mile trip and my girl friend and I froze. I had to turn the fan on low and the temperature down to about half way as far as cooling. It's good to hear that these compressors are so well built. I guess it's like "Seek" said that not much has changed, probably because what we have works so long and so well. Thanks!
Did it freeze UP. If so that means only two things. THE CCOT switch is stuck closed or it is BYPASSED. That system can not freeze over unless the CCOT switch is shot or bypassed.
The CCOT system is so simple it is not necessary to look else where for components. There are many new and rebuilt compressors around for replacements and any other part needed for this unit. The system does not have any moving parts in the system other than the COMPRESSOR and leaks !!
The low pressure cutoff is adjustable with a screw. I believe I have my cutoff set to 20psi, which would put the refrigerant at 22F at the switch. This also means the refrigerant is 22F at the entrance of the evaporator, but it heats up as it travel through. I'm not sure what it is on the other end, but it'll be a bit higher. Let's say the evaporator is sitting at 25F and the blower is circulating air that is 60F - it is pushing air through the evaporator that would prevent the thing from freezing solid, but there COULD be a thin layer of ice on the evaporator's fins. For any real information, I'd need something like a lab-grade humidistat, preferably a camera in the evaporator box so it remains sealed, and a ton of measurements to make any real statements to back up why my setup works. I just know it's setup for 20psi cutoff and that it blows sub-40F out the driver side vent to the right of the steering wheel using a Fluke contact thermometer. It's basically the same reason I don't see ice on the liquid line - it's near the exhaust, but that is a far greater temperature difference.
Also from what I understand, the oil in the system may not lubricate well/thorough at <15psi low, but that was just going off of research 4 years ago. It would also be much more likely to freeze over as 15psi would be 15F.
It works for me but I can't say it would work for everyone. I do have an electric fan on the car, but do not run it higher when the A/C is on. I'm pretty sure the condenser is doing a LOT of the work for me.
I should also mention that iirc, at 630rpm idle, the A/C compressor can't keep up at all and it blows like 15 degrees warmer than when holding it at 1k rpms. If memory serves me right, it was like 38F on the highway at a steady speed in best-case (I don't remember the cabin temperature) after 10+ minutes of driving, 45-ish with the car not moving and the rpm's help at 1000, like 60-ish just stopped and idle at 630rpms. This was back when I was running a mechanical fan with a new fan clutch. I think I may have a thread on it some place, from likely summer 2009.
Edit:
I will also say that I haven't driven that car in the hot summer heat for years now since it is no longer a daily driver. I could completely remove the A/C in this area now and not care, but I'd prefer to keep it on. My last experience with any of this was 2 years ago, and it had been on the car for 2 years prior without any issue. I don't remember the condenser temperatures or pressures, but they were high and hot. I also do not remember if I have the liquid line with the stock restrictor. I think it's the stock sized static unit - not one of those variable units that is supposed to help idle cooling (as seen above) that people seem to strongly dislike for reliability. I'm sure that is the one thing that would drastically help our systems with r134 though - a different restrictor.
Ok so you ran the set screw down to stop the clutch from dropping out. But i am amazed the evaporator does not FREEZE UP. Also you are running low on refrigerant with a steady low side of 20 LBS Gauge.That system is down charged 20 LBS way down charged!!!
As long as it's oiled adequately, I don't care that it's lower than normal. It can cycle all it wants on cooler days - I wanted the coldest temperatures on the hottest summer days. I grew up without A/C and always told myself I'd built one to make a car a mobile freezer (I had pictures in my head of ice forming on the windows). While I later learned why this wasn't possible, I could get close. It hasn't leaked out yet as far as I know, but I'd need another warm day to test it out this year. Not saying I'm an expert on these things, but I did my research and didn't see any reason for problems as long as I don't get my evaporator frozen up, which would make the cooling halt. If I was building a mass-produced vehicle, I'd want to be on the safe side too to get less warranty work. There is some extra to be obtained from the A/C system though, just as there is extra power to be made from the 5-liters of displacement. Everything can be modified to work on the brink of destruction, but if you plan beforehand, install everything correctly, and know how to monitor everything and use quality parts, things generally last.
I probably have 50 or so hours on the system. We rarely need it here. For all I know, the system could be inadequately oiled, but I haven't had a problem yet. I'd have better anecdotal data if I lived in the southern states. Still yet though, that car has been a garage queen for over a year now.
Well there is two sides to this story
1 The system is modified to do something it was not designed to do but the outcome satisfies your needs. Nothing wrong with that!!
2 It shows that the system is strong enough to TOLERATE IT.
So that answers the question that the system does not have to be replaced as 86 wants to do.
Your post confirms my post as the system is totally adequate to cool these cars with out any issues.
Just a thought !!! Running the system this way is most likely OK for your enviorment. (Where You Live ) But in a HUMID HOT CLIMATE the system is not working correctly and God only knows why it does not freeze over. Either way i appreciate your post as it helped what i was saying. Thanks!!
With all that being said, there seems to be a concern about freeze up. My car is a freezer when I turn my A/C on (no complaints). If it is running too cold this is where the possibility for the compressor to freeze up? I am running 1.9 lbs. of R134 and if I understand right that is about right for where I live. If I only turn my temperature control about 1/2-3/4 up would that help prevent freeze up? If I turn the set screw up to where where the clutch drops out more would that make my system not work as hard or be better for it? Like I said, I don't want to replace A/C system, I just wanted to know what to look for if and when my system dies.
The A/C system running extremely cold can only have problems if there is moisture IN the closed-loop system of refrigerant. When you pull heavy vacuum before charging a previously-open system, you remove nearly all of this moisture. The concerns of the evaporator freezing up would only clog the fins up with ice, making it so you get no airflow through it, and no cooling. This won't harm the system, other than the expansion and contraction being more than normal, eventually wearing out the evaporator a bit quicker (give anything enough time, it will begin to fall apart, and in this case, means it would start leaking). I wouldn't be concerned about the evaporator though, and unless you've modified the low pressure cutoff, you are still getting a 35-37F temperature from the condenser at best, which could get you 45-50F out the vent best-case. On a hot day, this will still seem very chilly.
Seek the system freezes the condensed moisture on the OUTSIDE OF THE EVAPORATOR surface. That is why the system drops out at 32 Lbs or app 35 lbs low side. That equates to app 35* across the evaporator so it does not freeze. A quick look at a properly working unit will have water coming out of the condensate tube. That is what you are concerned with when evap temps and clutch drop outs. The reason the clutch drops out is so the EVAPORATOR does not freeze up. It has nothing to do with the moisture in the system. Thanks
I understand this. If you read my post again ( I may have written it poorly), freezing temperatures can cause damage INSIDE the system (along with other inadequate cooling) if there is too much moisture IN the lines. The restrictor/orifice will clog with ice. What a properly charged system with low refrigerant will do is freeze the EVAPORATOR. Improper vacuum and foreign contaminants can/will damage the A/C SYSTEM. Freezing temperatures will make the evaporator's fins freeze, but not the A/C SYSTEM.
He asked about the compressor freezing up. This won't happen. A blocked restrictor/orifice can cause the compressor to push against a blockage though, which CAN damage it, but it isn't related to the compressor getting too cold.
Anyway, a cold system won't damage the compressor, and unless you've changed the low pressure cutoff, the system will stay a few degrees above freezing, all around. There isn't really anything you can do to make it not work as hard. It'll do what it does, and it does it well. As long as the thing was oiled (or preoiled) when first installed, it'll last for a long long.
Well we are not seeing eye to eye as the receiver drier takes care of moisture in the system and in 99.9% of the time prevents orifice tube icing and blockage .And a pump down of no less than 6 Hours is what i always do. And also the type of vacuum pump and how efficient it is there should be no internal moisture in the system . Well lets call it a day Thanks
ROBIN AIR TROUBLE SHOOTING MANUAL!!
If the system uses an orifice tube, there will be an accumulator between the evaporator and the compressor. An orifice tube sometimes lets too much refrigerant into the evaporator and it doesn't all boil. Since the compressor cannot compress liquid, only gas, the accumulator traps any excess liquid before it can get into the compressor. This also removes moisture that can block the tube. Dropping the clutch is how it controls freeze up. To low a charge or a CCOT switch set to low will cause evaporator freeze up.
86 the only moving parts in the CCOT system is the COMPRESSOR. If it works and the gauge readings are ok and the compressor does not make any noise your are ok. If it freezes up something is not set correctly or the system is LOW and or the CCOT switch is set to low or bypassed. Thanks
No disagreement here. Also, you shouldn't have to pull vacuum for long if you use a strong vacuum pump. Mine pulls down to 30 microns in ~5 minutes but I run it for an hour to get it down to 20 microns according to a micron gauge. Of course I don't have a ton of hours on this thing so it seals like new. I think anything below 500 microns is perfect for an A/C system, although you can get away with more. 20 microns is over 99.99% vacuum. 500 microns is closer to 99.9% vacuum. The accumulator handles the rest.
I do wish I had more use for that vacuum pump as it was spendy for the one time I used it. I use a noisy oilless one for other jobs, to keep my good one for specific jobs like A/C. So far it has only been A/C as nothing else needs the extreme vacuum. I worry for the lubrication and seals just sitting boxed up on a shelf.
We have a reclaimer combination system. I need this by law as the Clean air COPS might just pay us a VISIT. They did years back and we were GOLDEN!!!
Yeah, when I made some changes to my system years ago, I just went down to a shop and had them reclaim the refrigerant for free, then charged back up at home. About as good as I can get without one of the all in one machines. I don't think those machines typically come with a micron gauge? That's the most accurate way of knowing true vacuum and how much moisture and some contamination is left in the system. Hours of pulling vacuum seems like excessive wear for the machine if it's in great shape, but whatever works is all that's needed.
Years back i went on the roof of the shop and put back some covers that were loose on the AC shop system. The next day the Clean air cops came in with summons books and a load of pens. Someone dropped a dime on me and said we were venting freon. All checked out and the black suite feds took a hike. They had the typical white socks and brown shoes. Come to find out a local neighbor hates hot cars and blew the whistle on us. Thank God he moved to another town. Thanks
What are we talking about now?:toilet:
As for the stock A/C system if it ever breaks fix it back to stock. I've got R-12 in mine (I was able to find some after I replaced the O rings) and it works great. The compressor is big. It's actually bigger than the compressor in both the 2011 Focus and 2012 Mustang I've got. The system works much better than the system in the newer cars. The interior of the Thunderbird gets quite a bit colder than the other cars at a faster rate. I keep the system set on 70-72*, depending on outside temps, to keep from being frozen out of the car. The only draw back I've noticed is when accelerating I can feel the load of the A/C compressor on the engine. I've not noticed that with the newer cars, which have smaller compressors. The newer compressors may be more efficient but the don't give the cars the "meat locker cold" feel that the big compressor and R-12 in the Thunderbird does.
I had my system converted about a year ago, and it still is a meat locker in my car. That's all right with me, we do get pretty hot here during the summer. I never had any one complain about my car being too hot after a few minutes.
seek pretty much nailed it in post 4.
An improved drop-in replacement to the stock condenser is available from Spectra. http://www.rockauto.com/catalog/x,carcode,1140220,parttype,6708
If it is truly parallel flow, it'll give you a ~30% gain in condenser performance.
You could also put in a newer compressor (something like a Sanden or Seltec), but that would require new lines and new mounts for something which won't really improve performance and will barely help your mileage. Lots of work for very minimal gain.
Actually, I think you both hit the nail on the head. I have seen the Sanden of sell and I was wondering about that set up. So, if I ever need to replace mine, it sounds like it would work well. Thanks!
Just curious
The older system is designed for R12 and the replacement is RA134A. Have any of you checked a temp pressure chart???
The condenser in the car is well suited for a conversion and works absolutely perfect. The stock compressor as well is more than adequate for the car and does not need an UP GRADE.
You'll find most people disagree with you. There is a reason the SN95 condenser is quite a bit larger than the Fox (~50%). All things being equal, you need more condenser for R-134a than R-12. R-134a in our cars will perform adequately at speed with the stock condenser, but on hot days in stop and go traffic, the vent temps will creep up.
Here is the charts. Plain and simple.
http://www.ackits.com/aacf/ptchart.cfm
NOTE increasing condenser size is always better. The faster you condense the better no question on that. But where is the cross over point. Well looking at the TP CHART the 2 freons are so close a change out would not be noticed. RA134A is the closest freon to R12 and without gauge readings no one can tell the difference. I have dun back to back tests on both freons and when converted the RA134A is so close it does not even matter. Once again increasing the condenser is always better but with these cars not necessary. Check out the TABLES!!!
Condenser size is related to refrigerant thermodynamic properties. Enthalpy, latent heat of vaporization, etc. How much energy does the refrigerant contain at a certain pressure/temperature and how hard is it to liquefy the gaseous contents of the condenser input. P-V tables will drive the structural requirements of the condenser - how thick the tubes must be.
Two refrigerants could have very similar P-V tables and require vastly different condenser/evaporator sizes.
Then why do conversions WORK???? I have dun HUNDREDS with absolutely NO ISSUES!!! So question to posters. How many of you converted to RA134A and does your system work.
Tom Renzo Hundreds.
Any one else.
Is R134a less efficient than R12 ?
R134a is NOT less efficient than R12. Actually R134a is more efficient so it needs a bigger condenser. BUT the condenser in a modern car are quite adequate for conversion. As i posted a bigger condenser is always better but not necessary. Remember when converting you always down charge with 134A by 10-15%. This is because 134A is more efficient. So change out your condenser that is always a good idea but it is not NECESSARY. Just saying. Thanks
Condensers and Pressure Cutout Switches
When retrofits were first studied several years ago, it was thought that the condenser and perhaps the evaporator would have to be replaced to maintain an acceptable level of cooling performance on a retro-fitted system. Now, it is generally accepted that if an R-12 system is operating within the manufacturer's specifications, there may be no need to replace either part.
I'm not arguing that R-134a conversions don't work. I'm simply stating the fact that R-134a conversions require larger condensers to get equivalent performance of R-12 systems. The folks at the Automotive Air Conditioning Information Forum (http://"http://autoacforum.com/") will agree. They've done thousands of conversions.
The root discussion here is condenser size vs refrigerant. If you compare OEM R-12 condensers to R-134a condensers you'll find the R-134a are almost invariably larger than their R-12 counterparts. OEMs also began introducing better technologies (6mm piccolo, parallel flow) Why? A larger condenser is needed to get the same performance when converting to R-134a (Is the horse dead yet)?
i always had that question and you explained it well Jeremy, i wondered why during the transition to r134 days, cars that had r134 typically had larger condensors.
now i get it.
in theory, r134 was suppose to be more green for the planet, but the trade off was that it "doesnt cool" as well on "some" retrofit cars due to the oem R12 designed condensor.
The horse is DEAD and i should have KNOWN BETTER.
The evaporators are also a bit different on 134A units do you also change that??? No mention of an evaporator change out??
Ok Jeremy B i have a supply of R12 not only in one pound cans i also have several 30 and 50 LB JUGS. How much do you want. If a 5% reduction in cooling will make you AC system UNBEARABLE i will send you the proper amount of R12 and the proper oil to change back to R12. CASE CLOSED!!!
Let me know !!!!!!!!!!!!!!!
Condenser design is always getting better reason being newer cars have less frontal area. This in turn necessitates better Condensers. Once again as i said a bigger one is always better but not necessary in cars that are converted and have large frontal area. So i guess anyone that installed a front mount in front of their Condenser has no ac because of the extra heat from it???
We service LIMOS and when double evaporators are installed in some of the stretched units we do not change the Condenser. There is no room to do it. And i know about the difference in designs. Once again bigger is always better, Thanks
(http://i740.photobucket.com/albums/xx46/proguns/001-160_zpsea1418e1-1_zps5595852b.jpg) (http://s740.photobucket.com/user/proguns/media/001-160_zpsea1418e1-1_zps5595852b.jpg.html)
I have several cases of one pound CANS
(http://i740.photobucket.com/albums/xx46/proguns/002-104_zpsb8e351ea-1_zps41ad50ea.jpg) (http://s740.photobucket.com/user/proguns/media/002-104_zpsb8e351ea-1_zps41ad50ea.jpg.html)
I've got my Section 609 cert and run R12 in my cars, but thanks for the offer.
There are many variables that determine how a refrigerant performs:
latent heat of vaporization
thermal conductivity
heat capacity
pressure vs. temperature
density vs temperature
oil compatibility
etc...
I'm not going to go into how R-12 and R-134a compare in all those categories, I'll just throw out some quotes from various SAE papers regarding the two.
This paper is referencing whether you can achieve OEM level performance in new cars by direct drop-in of 134a into an R-12 system, not whether you can retrofit a system with 134a in an older car.
On the flip side, testing at non-idle conditions showed R-134a had more cooling capapcity than R-12.
Regarding condensers in retrofits:
Of note, in the two example cases given in the paper, one showed similar on-road performance between R-12 and R-134a, but poor R-134a idle performance. The other showed R-12 had better R-12 performance on-road performance and similar idle performance. Both vehicles were CCOT.
Regarding R-134a retrofits:
Regarding R-134a charge amount, which is related to density and system volume:
Although it should have been obvious that charge amount was simply related to refrigerant density and system volume, it was nice to finally nail that fact down. One of the two reasons to move away from tube/fin condensers was the large volume they had relative to their heat transfer capability. The other reason being superior heat exchange per given frontal area.
A 1989 paper compared a parallel flow condenser to a serpentine condenser and found:
The impetus of the paper was to reduce R-12 charge due to upcoming reduction in R-12 production limits.
SO we both have the same credentials. Funny thing is R12 is getting cheaper by the DAY. And 134 is sky rocketing. Could the 1234yf be in our automotive FUTURE. They approved it and it looks like a GO!!! Hay i did not know you were licensed and the offer i made you was a genuine one. Some might think i am a PRICK but i always like to help people HONESTLY i would have sent you everything including a CAN TAP. Thanks.
Now what will i do with the R12 and 134 Manifolds and reclaiming machines that will be collecting dust i have ??? Guess they will go in the pile of obsolete specialty tools like a VEGA timing belt tensioner tool. And as usual the pressures keep on getting HIGHER . Gm is using 1234yf in model year 2013. Time for new stuff again. But the plus side is i think it might be a gas that can be vented. The EPA has not answered this question. Going to be interisting. It is claimed it can be a substitute for both 12 & 134. Thoughts??? Thanks
I thought the offer was genuine, but the motives suspect. ;)
I've only read one SAE paper on 1234yf (what an odd name!) that did a drop-in retrofit in an R-134a vehicle. Performance-wise, the 1234yf had lower vent temps and discharge pressures than 134a. At the same time, I've read a few online articles saying it is illegal to retrofit 1234yf to 134a systems, but haven't found an actual source. I would assume the issue is due to 1234yf's flammability concerns (is is a hydrocarbon refrigerant). There is a special SAE standard for 1234yf evaporators.
Mercdedes performed a crash test about a year ago and had a fire when the refrigerant leaked onto the exhaust manifolds. They've swapped back to R-134a in the meantime and are pushing for CO2 as a R-134a substitute.
I think current prices for 1lb of 1234yf are ~$65. That's $2000 for a 30lb cylinder! :wtf: I'll stick with R-12 and R-134a!
I have been reading about CO2 but it is a little hard to digest for me. I am assuming you are a HVAC specialist.
I thought the offer was genuine, but the motives suspect.
Man you know how to hurt a guy. It was from the heart brother nothing else. I may come off as a PRICK but as i say i am always there for people any time or day of the week. Thank you
Thank you for the info on the 1234 Do you think it is PROPANE BLEND. I have not read in to it much but that is what it sounds like. I am going to research it a bit more. Funny how the AC systems change every 25-30 years. Does collusion ring a bell. Just saying. DUPONT just might be messing with us. Thoughts ???
Here we go again....
Here we go again with what. Something we are discussing and it is very CIVIL and informative to me. How about you. Care to join in in the discussion of new freons and pressures etc etc. If so chime in and lets discuss the differences 86. I personally have to do some research on 1234 and i will do that. Along with courses to sharpen my skills if a system show up in the shop. If we take in a crash car that has the stuff i cant tell the insurance CO OH WELL i do not know the system. So why the post 86???
:bowdown::bowdown::bowdown:
I had to re-read the post again. At first it sounded like another argument, but after reading it again I have to agree with you. Have a good day.
Here's a question, anyone ever convert to R-134 then back to R12? When I converted mine I put in the new accumulator, orifice, and condenser, and it just plain sucks here. Texas 105* summer heat and 50-70% humidity on a daily basis in July.... Call me a wimp if you want, I like it COLD! I'm thinking of going through it all again, replacing the accumulator and condenser, and flushing the out of it again. Just didn't know if anyone had tried that and it worked. I'd rather get the R134 working right, and I hadn't tried the bigger condenser yet. I have a huge electric fan too, so I know that's not a problem.
Does it cool well if you're on the highway?
If so, installing an electric fan to run with the A/C on will help your cooling, as would a larger condenser.
If not, I'd look at there being a problem in the system. Too much refrigerant, or not enough will affect the low side pressures, which are what flow through the evaporator.
Our low pressure cutout switches also are adjustable. r134 will cutout at a temperature 3 degrees higher than r12. If you adjusted the cutoff to be 3psi lower, the cutout would be at the same refrigerant temperature. I'd guess your problem isn't the system being 3 degrees different though - something wasn't installed right. For the best cooling, run a refrigerant level that stays just above the cutout switch pressure level on the hot days. I'd say shoot for 40psi low side at 1500rpms on a 100F day for a good dummy-proof system (45F evaporator temperature). Most cars today limit the cooling potential to around 60F anyway, so it would be nothing different than what people are used to.
Did you just have refrigerant added by a certain weight, or were gauges used to get the proper charge amount?
say what????????????????????
There is a set screw on the low pressure switch. While not really needed for adequate cooling, the cutout can be adjusted quite a bit to change when it engages. To cutout at the same temperature as the stock R12, R134 would need to have the cutout switch 3psi lower. This is only a 3 degree difference though, and it won't do a thing if the pressure isn't getting low enough in the first place (inadequate condenser performance).
I'm confused. I guess I'm not the only one running lower low-side pressures. I found this thread: http://www.stangnet.com/mustang-forums/threads/fox-r-12-pressure-switch-or-r134a-low-pressure-switch.869321/
I believe the stock system is set to cutout around 30-32psi though, not 25? From what I see, many cars seem to cutout around 25psi, so that is a bit different than I remember. I could be remembering temperature instead of pressure though.
Also, if I remember correctly, the compressor may start to have problems if running <15psi low side.
I should test the A/C in the car again to see what it's actually at. I'm pretty sure my high side pressures were higher than expected also, although I think I have a stock orifice tube. By higher, I mean 220psi on a cooler day and closer to 300psi on a 100F day. This with a 20-22psi low pressure would mean that the compressor is pumping too effectively for the side of the orifice tube. I believe these numbers were at speed (3x idle rpms), and not at idle. This was also sitting in the driveway though, with next to no airflow. I think I had a mechanical fan at that time, with a bad clutch. The pressure would be quite a bit lower driving down the road, or with my electric fan.
It cools ok to well on the highway. I do have an electric fan, pretty big one too. Not sure of the cfm rating but it flows. Problem is most if not all of my driving is city bumper to bumper. At first I put in the 1.33 kgs it said for R12, but obviously that was way too much. I did some reading about what some people have done and they put in about 80% of the R12 charge, so I put in 1 kg. Still too much I think. My high side pressures are 315 psi and low side 60 psi. Tomorrow if I get the time I'm going to pull a long 30-45 min vacuum and put a little less in. I usually shoot for low side in the 30s. Most of the customers cars I deal with I still get pressures around 175 high side and 30 low side with vent discharge temps in the low 50s-high 40s. Although that's on newer cars.
I work at a dealer so I have all the equipment and it's easy. I was just curious if anyone had gone backwards. I will someday try the cobra condenser and flush the system out real good again, but that's when I get a good teardown and rebuild on the car. Can't afford that right now, haha.
Your low side is to HIGH and the high side as well. with a CCOT this points to a bad compressor . Without seeing the car that would be my guess. Having a high side of 300+ cant be good.
Have you got enough air across the condenser? Obstructions, blockages, crud between the condenser and radiator? What RPM are you testing at? Charge weight in ounces? Most importantly: Environmental conditions (temp, humidity)? Right now at my shop we're in the upper 90's with matching humidity, I did an evac and charge on a Taurus yesterday and even with the fan running, and the blower on low, my low side only pulled down around 55 psi and my high side was hanging around 300. I sprayed some water on the condenser and high side dropped immediately to around 190 and low side responded by dropping to 30. Mid July weather is a bitch, and you can't explain the concept of a "design day" to a customer because they won't get it in a million years.
Yeah, the cooling of the condenser will have a huge impact on pressures. The cooler the A/C system is, the lower the pressures will be. Highway speeds have a lot more airflow over the condenser, so the pressures drop, and the A/C efficiency improves.
Charging by weight/volume of refrigerant is fine for estimates, but only the gauges will tell the truth. You can also only really ever shoot for ideal cooling in one specific condition. If you want cooler stop and go driving, you need to have good airflow over the condenser and refrigerant levels/low-side pressures down low. This will cause low refrigerant levels at highway speeds, and the compressor to cycle, making highway speeds not cool as well. In cooler ambient temperatures, the pressures will also be lower, causing compressor cycling. While you may not use A/C at lower temperatures, preventing compressor clutch wear from the cycling, note that the defrost also runs the A/C to help dry out the interior. You will get excessive cycling in the winter when using lower refrigerant levels.
They make "variable" orifice tubes that supposedly help low speed cooling, but I believe they are generally not recommended and may introduce problems.
The joys of compromise.
With NO airflow/fan in a driveway, I've seen 400+. Not good I agree. Airflow can cut that number in half and make what appears to be "high refrigerant levels" become normal.
Otherwise, with both pressures being higher than normal, the system is over-charged. If the low side is very low and the high side is very high, the orifice tube may be clogged from contamination. Most common culprit here is insufficient vacuum, so ice chunks cause a blockage.
I just finished converting an H valve system to orifice tube on a chevy. Low side @38 lbs High side @ 210 lbs and center vent air 39*@ IDLE. If you pour cold water on a condenser it will always bring down the numbers. Modern air conditioners normally use evaporator water to spray on the condenser. They make a well for the water to collect in and the condenser FAN picks it up and sprays it on the condenser. Naturally cars do not do this. But the engineers know that reducing condenser heat is the KEY for efficient operation. If a system approached 280LBS on the high side something is wrong. Not set in stone but in all the years i have been doing AC that is high. Normally the high side should be 100-120 LBS above ambient or 2,2 -2.5 higher than ambient if the system is correctly designed and working properly. And the low side should be 32-40LBS. This depends on ambient.
NOTE Most automotive systems have a large capacity drier to prevent icing of the orifice tube orifice. A failing compressor is 99% of the time the cause of orifice tube blockage. Just me
If the high side numbers approach 280-300+ the belt and drive pulleys will be overloaded. And if you fast start a shut down engine with those readings the compressor will lock and the belt will do a bounce and squeal. Read my post on the jeep FIX. And @ those numbers the system wont work correctly.
Bottom line here is you need tuns of air drawn across the condenser and fan or fans working continuously when the car is running with the AC running. If not the condensor will run hot and the system will never work properly.
An automotive AC system blowing 55* air is NG and a problem exists at ambient 90*
Dead on.
I think he needs to check airflow first, then refrigerant levels second. Phase change systems are pretty simple.
Ok guys. Not butting heads but, I have worked in a dealer for 8 years. Yes I checked airflow. I have no obstructions in front of the condensor. I looked up the fan, its a Flex-a-lite electric kit that is rated for 3300 cfm, which I think is far more than the factory mechanical fan would do. The ambient temps here have been around 100* every day with humidity anywhere from 30%-100% on average. The charge I put in as far as ounces (I use Kgs because out machine only reads pounds or Kg, not ounces) 35oz, the sticker says it requires 47oz. I had the same feeling about the compressor as well, but seeing as I'm using 134 in a 12 system, I'm not completely sure how it would react. I checked it on a cooler morning about 80* with a big swamp cooler fan in front of the car and it was able to pull down to about 62* discharge temp with low side at 42psi and high side at 230 psi.
Most likely if anything I need a bigger condensor and possibly the compressor, but I just don't want to put too much money into it right now since I plan on doing a big teardown on the car in the next year once I save up some more. I also heard about those Sanden compressors but doesn't sound like many people, here at least, like them all as much. May just stick to factory there. Really I was just curious if anyone had tried going back and forth. I do appreciate all the tips and tricks though.
The compressor is responsible for generating your high side pressures and they are where I'd expect them on a 100F day with adequate condenser cooling (along with the low side being correct). The pressures would drop on a cooler day. I'm sure you know that electric fan will only put out max air at full power, likely requiring a higher voltage to do so, and are running it so. Note that the CFM rating is for open air, and it doesn't mean a thing if you have restrictions before or after the fan (it could drop to <500cfm easily). Shrouds help here a ton, if your fan doesn't have much depth. The factory shroud works pretty well at efficiently moving the air through the entire radiator surface when using the mechanical fan. I would check things in the following order:
1) Is the fan getting air from the radiator, or from the condenser also? Is there a shroud/seal between the condenser and radiator to help it pull air through the condenser? If not, the air that gets pulled through the radiator will be from the area of least resistance. The stock condenser does NOT flow air well, so the air around it will be sucked in instead of from the condenser fins. Good shrouding should help drastically, while using the same, or less, airflow.
2) How hot is the condenser getting? I've never measured mine, but it gets too hot to touch. 120-160F would be a range to look for, the lowend being 200psi and the highend being 300psi. First degree burns can start around 110F and up, if that gives you any value to correlate to. I don't know how hot the outside of the stock condenser would get though. My Mustang condenser gets very hot along the outside of the frame.
3) Try less refrigerant.
4) The compressor could be failing, allowing high pressures back into the low pressure line. What oil are you using in the system since the conversion?
I don't think the orifice tube can break in a way where it allows MORE flow, so that should be fine. If the above are fine, the r134 should work fine. Even the r12 would work better with the above checked or fixed. I would worry that if you converted back to r12, you might find it also performing poorly, but probably a bit cooler in stop and go driving.
If anything, I might add just a bit MORE refrigerant. I'm running 38oz in mine, and even in this heat it's been working great. Having said that, I set up a Fusion fan to run as a 2 speed fan with the low speed being for AC, combine that with my original R-12 condenser and at a stop performance suffers a bit. If anybody knows of a condenser that's more efficient and fits our cars, I might just throw one in.
If you want to know if you're dealing with environmental stress, get a hose and wet the condenser down while the system is running and you have your gauges on it. If high side drops and then low side follows, I'd say you've got a hot condenser problem, which considering the environmental variables involved, you may not be able to do anything about.
More refrigerant will just increase the system pressures. At idle you have two things working against you. The airflow is lower than when moving, so the condenser isn't cooled as well. The compressor is spinning at lower speeds, so it doesn't compress as much of the refrigerant from the low side. Your lower side pressures will be higher and your higher side pressures will be lower. The orifice tube is a fixed restriction, so idle performance will always be lower than at cruise. Thermal expansion valves can change dynamically to make low and high speed temperatures more consistent by allowing it to restrict more at idle when the compressor can't keep up with the loop.
SN95 Mustang condensers are almost a direct bolt in. The line fittings are right where they need to be. I think I just used some metal stock to hold it in place against the radiator support. I'm sure I took pictures way back when, but who knows where they are today.
Plain and simple lets cut through the BS. If your discharge temps are 62* that system is not working correctly. Weather a dealer tech or a weekend worrior that system is not working properly or has an issue. Exact pressure readings and vent temps can be posted. I would like to see what they are doing. Once again 134A is more efficient than 12 and that is a fact. That is why you always charge 10% LOW when converting. Here is a tip if i MAY. Normally an orifice tube should be .065-.070 thousands of an inch. This will support either 134A or R12 nicely. More freon does not mean a colder running system if it is charged correctly. I converted an H valve system to orifice tube. It is 101* today and at idle the unit blows 38-40* Blowing 60* air is not going to cut it . Also is the blend door working correctly. And if possible cut the coolant flow through the heater core and see if that helps. NOTE some engines need full flow through the core so check that out before trying this!!
Conclusion as i see it. Your pressure numbers are close. Normally a low side at 34LBS and a high side at 200 is ball park. So it is time for you to break down the system and check the valve . Or better yet replace it. This is the only way to find out what is going on. One other question is the low side condensing on the hose?? Is it cold to the touch and dripping water including the vent for the evaporator. If it is not condensing the system is in need of repair . just something else to check. Good luck!!
Flex-a-lite exaggerates their cfm a bit. I'd expect it to be ~2900 instead of 3300. As a reference, the 16" Taurus fan flows ~3800 cfm (30% more than the Black Magic). MN12 fan flows ~4300 cfm (~50% more than the BM). IMO, the BM isn't adequate to give acceptable A/C performance for our vehicles.
http://www.rockauto.com/catalog/moreinfo.php?pk=325771&cc=1140220 Parallel flow drop-in. I'm removing my SN95 condenser and putting one of those in my '87 T-bird once my HGs are replaced.
How do you know they are BETTER!!!
This is a good point that I didn't think about since we were focusing on high pressures unless the condenser was manually cooled. Airflow from the evaporator into the cabin could greatly affect cooling also. Some people (rarely) get blockages in the evaporator from debris. The blend door is the other possibility.
He did mention that the car cools better on the highway though, which points toward either inadequate condenser cooling, refrigerant level, or compressor.