Fox T-Bird/Cougar Forums

The car 88 T/C built 302 S/C 5spd 470 rwhp, the issue overheats only with A/C on at highway speeds.At steady 2K rpm it starts to creep in temp from 170 up to 210,that's when I turn off the a/c and starts coasting to cool it back down. Without a/c on you can drive all day long without issues. even city driving with a/c on it seems ok. 

160 hi flow t-stat runs at 170ish w/o a/c on
Mishimoto rad new
Flow Kooler hi flow w/pump
Boxed the rad in for more air
50/50 mix
V6 Contour elec/fans
Mach 1 chin spoiler
New condenser


The solution  ?????????????? Thank you.

AC hi and lo side pressures?  What is your CAC setup with the blower, is it air to air, air to water, closed, none, and where are the heat exchangers if indeed you are using any kind of CAC? Is there any kind of debris or blockage between the condenser and radiator? Also, I'd like to remind that whatever your t-stat temp is, 210 is considered to be normal.  You say you have a Mach I chin spoiler, pics? A lot of TC guys here have cooling problems because of missing/damaged air dams.  Since you've got electric fans, do they (or at least 1) run when the compressor clutch is engaged?

Not sure what the a/c pressure is at hi or lo side or what it should be or how it affects my water temp?Vortech no intercooler, rad and condenser are new and free of derbies, my fans are always on. The chin spoiler is from late model restorations the cheapest one they sell its about 3-4 inches longer on each side just cut those ends off, and i had to notch the corners on the inside of the chin spoiler to follow the birds tighter radius at each corner. When i take some pics ill try and post.

The higher the hi side pressure, the hotter the condenser will be, and the hotter the condenser, the lower the air quality is when it flows over the radiator. The next thing is to verify coolant flow.  At the shop we have a tool for this, but I don't know how to tell you to check it.  What does it mean "boxed the radiator in"?

I'd really wish I could watch your AC pressures.  I think that would tell the whole story, because the difference between ac on and ac off as it relates to cooling system performance is going to be the temperature of the condenser.

Here is a properly working system in 90*- 95* weather at 1100 RPM

(http://i740.photobucket.com/albums/xx46/proguns/003-69_zpsc953d25e-1_zpscdbad97f.jpg) (http://s740.photobucket.com/user/proguns/media/003-69_zpsc953d25e-1_zpscdbad97f.jpg.html)

(http://i740.photobucket.com/albums/xx46/proguns/005-30_zps354b436f-1_zps4e99d92e.jpg) (http://s740.photobucket.com/user/proguns/media/005-30_zps354b436f-1_zps4e99d92e.jpg.html)

Sounds like your radiator is clogged or to small. Or not enough air across it!!

Tom is the hi lo pressures based on how much freon is in the system or will the pressure rise if the condenser temp are not properly managed ? The rads new with very low miles on it, I would lean towards to small or my contour fans are tired,not sure the water pump is a flow kooler which is suppose to increase flow by a bunch.

thanks

Your answer is yes, or specifically "all of the above".

Angry i posted the mach chin spoiler pics in body and appearance section

AC pressures are a combination of Outside temps system charge to an extent and how much air and the size of the condenser

In the body shop The insurance companies sometimes require aftermarket parts. This can be tricky as we replaced a condenser in a Toyota and an aftermarket unit was used. IT DID NO WORK. I ordered one from the dealer with vin verification and the system worked perfectly. It takes years to learn AC as every system is different and even different in the same cars. But you need to see what your pressures are and you need a pressure temp chart to verify operation. Thanks

A couple of questions

1 how big is the radiator.
2 what kind of fans and how big?
3 do you have a stat and what is the temp of the stat.
4 does the radiator have good air flow at high speeds?

You may be over cooling just a thought!!!

T stat 160 hi flow
rad is a stock size 2" thick 2 core aluminum
fans are from a v6 contour I think there twin 11" they seem to pull a lot of air to keep it at 170-180 without the air on at highway speeds

Well the water cools the engine and the radiator cools the water. With tha AC on this process is not working??? Just a thought if you slow down the water flow through the radiator with a regular stat at 180* this might allow the water to stay in the radiator longe and cool better. Normally at highway speeds there is plenty of air across the radiator so the fans are a wash??  (i think) Try replacing the stat with a higher one and go from there. You need restriction in the system to allow the coolant to stay in the radiator long enough to be cooled. You just may have over cooling ??? Also does the car have the lower valance installed??? It needs this to direct air flow through the radiator. Remember the TC nose is completely closed off to air flow.

http://www.foxtbirdcougarforums.com/showthread.php?35863-Mach-1-chin-spoiler-pics

Yes it has a Mach 1 chin spoiler ,not sure where i read it i think it was a water pump company site stating that by slowing down water flow to keep it in the rad longer also keeps it in your hot motor longer having a negative effect on cooling. i think i'm leaning towards a larger better rad but not before having the A/C pressures checked as the car is fine at highway speeds regardless of temp. Or get new fans to draw more air with ac on not sure anymore.

I would agree with Tom on this. If the fans are enough in stop and go traffic, I would find it hard to believe they are the problem at highway speeds.

Except that you shouldn't be running fans at highway speeds. When under fan cooling at a stop, you have much lower thermal load to deal with.  At highway speed, you have sufficient high pressure in front of the cooling equipment as to overcome the equipment's ability to allow air to flow through. You're flowing as much air as can be allowed by the condenser's design, and you can only flow as much air through the radiator core as you can get through the condenser core first. A spinning fan under those conditions can reduce your potential airflow, since the capability of the fan is lower than the raw capability of the condenser core.  Your fans should be depowered so that the blades are just along for the ride.

I agree Foe, shouldn't need the fans on above 35 mph or so. Never considered that leaving them on could block air flow. I was looking at some photos of the contour fans,  it looks like the shroud may cover the entire radiator, maybe at highway speeds the shroud is limiting the air flow also.

double post

Anyone in the know knows that a constantly running fan is NG and actually can reduce the engines HP. BUT i have been known to run some dual fan setups on low speed. That would be ONE fan on low speed and never both of them.

all valid points and theories  but the fact of the mater is at hwy speeds without the a/c on and the fans shut off the temp starts to increase once you turn them back on it starts to drop so they are actually doing something. im sure the

condenser is a bit of a restriction.

Then either the radiator is to small over cooling or the air over the core is not there!!!

If you've got to have the fans running at highway speed, I'd take a serious look at how much air is getting up into the cooling equipment.  TC guys have problems without a proper air dam, but from the pics, yours looks adequate.  Possibly it's not directing air up from under the bumper properly.

with the car at idle and the fans on i took a 4x4 piece of newspaper and placed it under bumper holes and it sucked it right up lots of draw. on a 60-70 deg with cool air and sunny out at highway spd 70mph rev 2k fans  & a/c off temp went from 172 to 180 and stayed. in 4th at 2200 rpm 50mph no fans temp goes up from 172-190 turn fans on cools to 172, turn the fans back off do the same speed as before but in 5th less rpm and temp barely climbs mind you outside temp is about 55-60 deg. will do some more testing when the weather gets warmer. thank for your imput

OK so when the RPM slows down the TEMP goes down..

With that does the water pump slow down as well ?????

Over cooling crossed you mind. Just a thought!!

Does the TEMP drop if you run the heater full blast on the highway ??? Does that make the temp come down ???

I did think about over cooling and i did try a regular 180 t stat last year no difference , i have not tried the heater core fan to cool the engine what are your thoughts there? There is a interesting read on cooling systems @ http://www.flowkoolerwaterpumps.com/cooling_faq.html in the cooling facts section. yes i do have one of their water pumps installed this season and no difference, so i'm leaning towards rad a buddy lent me his 3 core copper rad which has the exact same fans as mine to try but not before i take it to a local rad shop they said they could have a look to see if i have enough fan,i went to ask on how much to make me a copper rad like my friends and he cant believe that the aluminum rad i have wont cool my car so he told me to bring it by.

Well copper cools much better than ALUMINUM!!! I am not buying the guys theory on over cooling. No stat or a stat that is to low causes cavitation in some instinces. Just a thought. Running the heater at full speed will tell you your radiator is to small if the temps come down. heater core is basically an AUX radiator and cools the engine as well as the main cooling system. Good luck!!!

quick update had the a/c pressure checked on 80-90 deg day hi side was at 325 psi we dropped to 230psi did a 10 mile run or so on hi-way and it didn't go past 190 ill have to test it on a longer run to make sure its all good.

230 is not excessive, but I feel like it could be lower if your condenser was being cooled better.  I say that because high side pressure is directly affected by the temperature of your condenser.  If you want to see this relationship, monitor the high side pressure while spraying water on the condenser.  There is some contention as to the suitablility of the original R-12 style condenser in R-134a retrofitted systems, some say they work just fine (mine works well enough for me, but my cooling system thermal load is lower than yours), others will say you should have an updated Serpentine or Parallel flow style condenser as they disperse system heat more efficiently.  I suppose a worthwhile question to ask, since your condenser is new, is what style did you install?

Well at 325 that is app 165* not to hot. But high for a car AC system. You fail to say at what RPM which is important. What was the RPM??? And you decreased the pressure by 100 PSIG. This tells me the system was overcharged. People not trained in ac always over charge systems. They think adding more freon makes the system COLDER. NOT TRUE. Whenever converting tou must use less R134 as it is more efficient than R12 and that is a fact. Also installing a more efficient Condenser is fine but it still has to dissipate heat. And that heat is right in front of your radiator. Once again either you radiator is to small or the air passing over it is not enough. Good Luck!!!

By the sound of it, hi side got to 325 before the cooling equipment caught up and settled to 230 with airflow.  You see that when the fans don't kick right away or the car has a belt driven clutch fan.  I'm more concerned about the stable pressure of 230 with airflow.  It's not outside the temp/press chart, but I would like to see it lower.  As for charge level, Mine works best with 40oz or refrigerant, about 9% below spec.  At spec (2lb 12oz), I can't get discharge below 50f.  As per usual, your results may vary.

Normally the high side pressure should be 40* above outside ambient temp. So at 90* his high side should be 130* or 200 PSIG!!


OK How did you reduce the pressures on the system. Did you REDUCE THE CHARGE. Another words did you remove freon from the system to reduce your pressures???

Proper reading at 90* with RPM at 1400-1600

(http://i740.photobucket.com/albums/xx46/proguns/003-69_zpsc953d25e-1_zpscdbad97f.jpg) (http://s740.photobucket.com/user/proguns/media/003-69_zpsc953d25e-1_zpscdbad97f.jpg.html)

Discharge temps high fan AC set to inside air or MAX OPERATION!!

(http://i740.photobucket.com/albums/xx46/proguns/005-30_zps354b436f-1_zps4e99d92e.jpg) (http://s740.photobucket.com/user/proguns/media/005-30_zps354b436f-1_zps4e99d92e.jpg.html)


NOTE just look at the gauge it has the temp pressure tables right on the FACE for the freon you are dealing with!!!!

This system is charged properly and working efficiently. Bottom line it is all in the charts. Pressure and temp this is not brain surgery.

Once again i am leaning to a cooling system on a marginal basis. His cooling system is marginal at best. He needs more cooling.

No, at 2lbs 8, my pressures are just about what you're showing.  But that's what I'm saying, by the chart, he's not out of spec, but it is higher than what I'm used to seeing.

Care to explain this in more detail?

FOE nice chart but what is the FREON IT REPRESENTS. That cant be 12 or 134 in a car system. The only charts that i have seen this high is posted by HONDA. And they normally dont run that high.  Pressures are to HIGH. Years back i came up with a wiring mod for the JEEP CHEROKEE. They delayed the AC condenser fan way to high. They turned the fan on @ 360-400 PSIG. This made the belt squeal on start up and running on some cars. It also burned out water pumps as mechanics were tightening the belts way to much to compensate for it.  I made a change in the fan system to eliminate this issue and every dealer and owner in a hundred mile radious came to me to repair it. Made a tun of cash on that one. 

Question when checking ac systems do you see the high side over 250* @ 100* outside??? Only if the evaporator is restricted or the system fan is not running or whatever. Over 220 PSIG is really pushing it. Just me and the TEMP CHARTS!!! What do you find with normal pressures on the cars you service at the dealer you work at. Just curious foe thanks

R134A is more efficient so you use less freon!!! When charging a converted system you charge DOWN. 10-12% BUT It runs at slightly higher pressures than R12.

Ok, I would say my chart was 134a. But lets be sure.  Here I've got the R12 chart right out of our very own 88 Thunderbird Workshop manual.


And these are R134a tables taken from the Workshop manual for 98 Taurus.



They sure look like the same chart. I'd have to put hands on an original R12 vehicle WSM, as I suspect AllData may have swapped out the Charts for R134a. The Taurus charts came directly from FMCDealer.com Although it's worth noting that the test notes in the R12 chart specify blower to max, where in the manual, R134a charts specify blower to minumum.

What should the high side pressure be?

Like i said 40* past ambient is about the norm. More than that is something i would not like. Just me.

ROBIN AIR TECH SPECKS FROM THEIR ENGINEERING DEPT


With R12 systems, high side pressure is usually 1.8 to 2.1 times ambient temperature. That means on an 80 degree day, with moderate humidity, we would expect to see between 144 to 168 PSI on the high side. On hot humid days (with R12), you could say ambient temperature plus 100 PSI., and be pretty close.

With R134a it's common to see high side pressure between 2.2 and 2.5 times ambient temperature. On that same 80 degree day we would see between 176 and 200 PSI on the high side of an R134a system. The system operates in a specific range based on outside ambient temperature. Normally around 200 PSIG But not set in stone.

The owner of the car reduced the charge dramatically and lost high side pressures and in turn lost heat. He now does not overheat according to his post at highway speeds. So charging an AC system and knowing how that system works is what we are talking about. That is why a license is required and schooling to understand said system. I am most certain you have a license working in a dealer. It is not going to AUTO ZONE and dumping cans in a system. I was in the parts store this weekend and it was loaded with people buying FREON. Not one can or two they were buying like 4 cans and the counter prson wanted to sell them more. ((( WHAT ))) You know the ones with a low side gauge on the can. Normally one can is more than you need for top off.  How can anyone know what a system is doing without high side readings. Anyway it is always great talk shop with you FOE Thanks

Geez Tom....good fix on the jeeps!  Good thinking

Travis

P.S.  as they say....not just a hat rack!

just to answer a few questions the car was 325 psi on hi side at idle 700rpm with all cooling fans on, i released the pressure (freon) from the high side valve to 230 psi . short drive and no overheat on highway, will have to wait at least a week for  some hot weather to try on a longer trip as temps have dropped where i live.

I did 3 AC repairs today. And was thinking about your car. The S10 blazer i fixed ran a low side of 28 and the high side was 150.  Vent temps were 38* and i was happy with that. Thinking about your high side numbers came to mind and it hit me. 86 was questioning or thinking of replacing his stock system!!! But you just proved that the stock system retrowed with 134A had that compressor pumping out almost double what it was designed to do with no problem whatsoever. Those old systems were really over BUILT. YOU PROVED IT THANKS. 


Clearly your system was over charged by a lot. When you mentioned those high pressures i knew the system was over charged. No question in my mind about that. So as i always say people normally over charge systems. But in reality an undercharged system is always better than over charging. Glad you hung in and found the problem. Good Job!!! I think you are good to GO!!!

Just for the record if you are curious what i did to the JEEP for my mod

SIMPLE!!! I installed a DIODE on the clutch side contact of the AC CLUTCH RELAY. Then the other side to the pull in winding of the condenser fan relay. When the AC clutch was commanded on by the clutch relay the diode fed Battery to the winding of the fan relay. Naturally the fan ran every time the clutch was energized. The diode was necessary to prevent a back circuit.  A 2 minute FIX at the relay fuse panel under the hood. The diode i bought at Radio Shack for a couple of bucks. The results were amazing and fixed the issue.  The high side never went over 160 LBSG. The belt never squealed again i made tuns of money with a 2 dollar diode 2 minutes of work and laughed all the way to the bank. The local JEEP dealer sent me all his work on this issue and they were happy to pay me. Their techs were told by JEEP that the the system as designed by them was not to be changed and nothing was wrong. Well they were FULL OF IT. Thanks Tom

That's a sweet fix....great thought out process...but that is what makes u a great tech....then add a few years experience.

If I lived in CT I would be a customer... Its a rare nowadays.  Just plug in the ODB2 and it will show us the way.
Good techs know better.

Travis

Im impressed!

To OP, go get professional AC service.  Evac charge, the whole deal. be sure to remind them that it will take less refrigerant than is on the underhood label.  Specify 2lbs 6oz to 2lbs 8oz.  I don't know if that's how it went in the first place or if you charged it with cans, but go see a pro to make sure things are right.

Final post on this subject. After getting the hi side pressures down in a/c system it seemed to be ok it would run around 195 on the high way w/ ac on. A series of events alternator power wire fried towed home fixed it,car started running hot no ac on though i might have blown head gasket when i was trying to limp it home with battery dying, i'm boosted u get the picture loss of ignition fuel under load it could happen.  Negative on gaskets,did plugs and finally did the T stat low and behold car runs cooler than ever once again proving i'm as stubborn as a ass maybe it wasn't as new as i thought. Car did start running like  towed to buddys shop leading me to drop fuel tank feed line partially popped fixed it tried to start it starter locked up would barely crank than it started cranking and wouldn't stop, changed relay and starter had a spare,checked plugs they where done so was oil. While installing new plugs i popped a vac line I didn't like how it was rooted, it was full of fuel lol got a new diaphragm for the aeromotive reg and now shes running.changed the oil again as it was still contaminated. still wasn't running good I put a heat gun on all header tubes 1 was way colder put a old plug in it and temp went up, driving around with the a/c its at about 180 or less. Pulling injectors out next as i'm not pleased with the way its running its been a fun couple of weeks, just glad its not head gaskets.