cold my AC work better than this?
Thread Starter
Instructor
Joined: May 2005
Posts: 218
Likes: 0
From: Gaithersburg Maryland
should my AC work better than this?
If the temperature is below 80, OR I am rolling down the highway, my AC works fine, but if the temp outside gets over 80, AND I come to a stop light, it starts to blow less than chilly air. I have had the freon topped off, and it is still the same. Is this typical? Is there something wrong with it? What do you think is wrong, and how can I improve it's performance? Thanks.
Last edited by Dartvader; Jun 15, 2005 at 09:42 AM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
If you could get your operating pressures that would help. Could be too much or too little gas; a plugged up orifice, possibly a funky low pressure switch - is it cycling off at that outside air temp? It shouldn't be. Also, make sure the area between the condensor and the radiator is free of debris and that the condensor is clean - if shooting water from a garden hose on the condensor causes a significant drop in vent temps, there's a good chance it's just an air flow problem and if both fans are cranking (make sure they're staying on), you need to get the bugs, dirt or whatever else is there out of it.
Thread Starter
Instructor
Joined: May 2005
Posts: 218
Likes: 0
From: Gaithersburg Maryland
Yes it DOES cycle on and off when it sits idling in hot traffic. I have installed one street rod AC set in a car, but my knowledge of how it actually works is pretty limited. It's one thing to hook up all the parts, and another entirely to figure out why it doesn't work right. What would this cycling tell us? I will pop the hood and watch the fans, and will check for debris. The engine temp seems to stay right at 215 or slightly above which seems fine to me.I gather from what you have said that this is abnormal behavior: that the AC on a Corvette should be able to keep up with hot weather. Thanks
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
The AC will blow colder overall with the vehicle moving because its getting air forced through the condenser. Remember, these cars are bottom feeders and do best with the vehicle moving. 
Team Owner
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From: Athens AL
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No, AC on an older vette really isnt able to keep up with hotter weather, the whole system is a bit weak but especially the blower.
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From: Fort Knox, KY
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And it's normal for R-12 to generally get cooler than R-134a refrigerant, especially in high humidity scenarios.
If your car has the smoked glass roof, it's going to experience higher interior temps, too. Especially if the car's been sitting out in the parking lot at the office or something.
You can buy a product called "Max Cool" synthetic A/C booster for R134a systems at AutoZone. It cleans your compressor and helps your overall system achieve cooler temps. Try it. It works! I added it both to my Vette and my DD.
If your car has the smoked glass roof, it's going to experience higher interior temps, too. Especially if the car's been sitting out in the parking lot at the office or something.
You can buy a product called "Max Cool" synthetic A/C booster for R134a systems at AutoZone. It cleans your compressor and helps your overall system achieve cooler temps. Try it. It works! I added it both to my Vette and my DD.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
At 80 degrees, it shouldn't cycle at idle. The low pressure switch should be set to open the circuit at 22.5 psi. If it's below capacity or restricted, the amount of liquid refrigerant entering the evaporator boils off immediately and can't absorb very much heat. What reaches the switch doesn't have enough pressure to keep the contacts closed, so the circuit opens. I'd get the pressures checked. R134 doesn't cool as well as R12, but every car I've owned or rebuilt with R134 has had idling vent temps of 48 to 52 degrees, so I think your Vette's a/c needs some work. The key is to keep it running so that it can absorb some heat and with unrestricted air flow through the condensor, it'll probably be cooler.
Last edited by SunCr; Jun 15, 2005 at 12:22 PM.
Pro
Joined: Oct 2003
Posts: 506
Likes: 12
From: Savannah GA
put gauges on it, hold rpm at 1500. Watch the low pressure, high side will vary from outside temp. If the pressure drops below 25psi or so and the system cycles off you are low on freon. It should have enough to keep it from cycling off this time of the year.
For sure, a vette will warm up at idle. Testing usually calls for 1500rpm for a few minutes and temps in the 40's.
I think there is a website, autoac.com or something, there are guys that will help you out if you want to learn.
JS
For sure, a vette will warm up at idle. Testing usually calls for 1500rpm for a few minutes and temps in the 40's.
I think there is a website, autoac.com or something, there are guys that will help you out if you want to learn.
JS
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Melting Slicks
Joined: May 2005
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From: Atoka Oklahoma
St. Jude Donor 06
it could be a slue of anythings....i would start with easiest and cheapest first....clean condensor probably has trash in it, also check out the fins making sure they are straight. i have also seen evaps plugged up. a plugged up condensor will make the head pressure climb.
