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Air Conditioner vent temperature

Does anyone happen to know the factory spec for air conditioner vent temperatures on our cars? With the climate control set to 60* and the fan on high I get a vent temperature of 39* at idle, 37.5* at 1200rpm. I'm just wondering because lately when it's been 90*+ outside I've had to set the climate control to 68* to get the "freeze to death" cabin temperature I used to get with the system set to 70*.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

Air Conditioner vent temperature

Reply #1 –
You still running R12 or did you convert to R134a?
CoogarXR : 1985 Cougar XR-7

Air Conditioner vent temperature

Reply #2 –
Quote from: thunderjet302;451036
Does anyone happen to know the factory spec for air conditioner vent temperatures on our cars? With the climate control set to 60* and the fan on high I get a vent temperature of 39* at idle, 37.5* at 1200rpm. I'm just wondering because lately when it's been 90*+ outside I've had to set the climate control to 68* to get the "freeze to death" cabin temperature I used to get with the system set to 70*.

At those register temps you're close to(if not already into) freezing the evaporator, no chance you're going to get one colder without freeze up... Probably already is freezing at lower blower speeds, likely could benefit from a slight increase in refrigerant level... Which BTW if system is down a slight amount, would increase register temp not lower it... If it isn't freezing, leave it as is...

Air Conditioner vent temperature

Reply #3 –
Also remember as ambient temperature goes up the ac system pressure goes up as well which could make it more or less efficient depending on how much refrigerant is in the system

I've gone through this whole dilemma with my wife's car and ended up having to take some freon out in order for it to work great all the time including 105+ degree days
1987 T-Bird TC: 5-Spd, 5-lug conv., CHE Rear CAs, '04 Cobra wheels and 13" Brakes, Vac Assist conv: '93 Cobra BB/MC & Wilwood PV, Gutted/Knived Intakes, T3 turbo, RFE6 Mani, Stinger 3" Exhaust & Oil Feed, 255HP Walbro, Kirban AFPR, RR Cam, Esslinger Cam gear and Round Tooth Conv., Gillis Boost Valve, Speedway Dual Valve Spring,  K&N, 130a 3g Alt conv., 140mph Speedo
Running Better Than Ever :burnout:

Air Conditioner vent temperature

Reply #4 –
Quote from: CoogarXR;451050
You still running R12 or did you convert to R134a?

I was running R12 till last year. I had a replacement o-ring fail (after 8 years) and the R12 leaked out of the system. Since it's easier to come by R134A at the parts store I had the system converted last year to R134A. It was vacuumed out and refilled. It worked fine last summer but it wasn't as hot as it has been the last few days, hence why I noted the drop in performance.

I believe I corrected the issue however. I replaced the factory pressure switch with a new one calibrated for R134A. The cooling has improved back to previous levels. I was driving around in the Thunderbird with my wife today and she complained the car was too cold with the climate control set to 70*. It was pretty cold, as the old saying goes, "like a meat locker" in the car. Just how I like it :).
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

Air Conditioner vent temperature

Reply #5 –
My black Cougar will still cool really well.  On par with new vehicles.  I love my 88.
Mike

Air Conditioner vent temperature

Reply #6 –
Quote from: mcb82gt;451077
My black Cougar will still cool really well.  On par with new vehicles.  I love my 88.

The Thunderbird does get quite cold inside. I've noticed the Thunderbird and our '12 Mustang will get cold enough to freeze a person out of the car but our '11 Focus not so much . It gets cold just not meat locker cold.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.
 

Air Conditioner vent temperature

Reply #7 –
Quote from: TurboCoupe50;451051
At those register temps you're close to(if not already into) freezing the evaporator, no chance you're going to get one colder without freeze up... Probably already is freezing at lower blower speeds, likely could benefit from a slight increase in refrigerant level... Which BTW if system is down a slight amount, would increase register temp not lower it... If it isn't freezing, leave it as is...


Exactly - when I rebuilt my system years ago with all new parts, and late 90's Cobra condenser, the lowest I could get without the evaporator freezing over was a little under 40 degrees vent temperature. Setup to blow cold on a 100F day, but compressor cycles often, and doesn't get as cold due to the cycling, on cooler days. If I remember right, the low pressure cutoff was set under 20psi, barely enough to keep pumping oil through the system, but sufficient charge to keep the compressor turning just above cutoff at 3k rpms on a 100F day. Idle was in the mid 40's temperature wise.

Haven't touched that car's air conditioning in years now.
1988 Thunderbird Sport