Guys,

I have an issue on my 91 Camaro where the AC running causes the car to want to over heat? When the AC is off, the engine runs at the same temp consistently and rarely see a temp change when it's at running temp. However, if i turn the AC on, the temp will climb to the point where it wants to overheat.

At this point, I have to turn the AC off and turn the heat on to pull the heat out of the engine until it goes back to normal running temp and stays there. Has anyone else had this kind of problem before?

My suspicion is probably the electric fan, but if it was messed up, wouldn't it make problems even if the AC was off?

Scott

 

Single fan? Dual fan? Which of them are running with the A/C?

 

It's a single electric fan. Not sure of the make though, it was already installed when i bought the car.

 

What is the temperature??? These cars with the A/C on in traffic will run @220 deg.

 

I have the same problem but i have a mehcanical fan

 

With the engine not running and the key turned to on, when you turn on the AC does the fan run?

 

Is it the original fan?

What do you mean by wants to overheat? How hot is that?

 

So is the fan supposed to automatically come on when you switch on the AC?

 

Yes, the fan is switched on in two ways if its the stock system. Either the temp sensing fan switch or the AC switch ground out their lead to the fan relay that tells the fan to run. Go to the electrical section of the technical articles on this site and check out the single fan descriptions. The fan should go on when the AC is turned on with the HVAC slider to AC or Max Cool

 

I had a heating problem for years.My 1988 Camaro IROC 5.7 came with all the gadgets, however, I don't think it was properly engineered at the factory. I tried a griffin aluminum radiator. lowering the temperature gadge, reseting the timing, in the end, if it was a hot day and I was in stop and go traffic, up went the temperature. My final solution was rather dramatic, I rebult the engine, used Edelbrock 202 aluminum heads aluminum water pump and headers. The temperature roblem dropped like a stone.

 

Does anyone know the capacity to recharge a retrofited airconditioning system with R 134 a?

 

ok. there's a lot going on here. haha.

my iroc had this same problem. (i say "had", but i'm not positive the problem's been solved). it ran about 220 with the a/c off on a warm day, so it was a little warm. but with the a/c on, even on the highway, it ran well over 260 and would start to cool down when the a/c was turned off. what i did was remove the homemade "ram-air" ducts running from the fog light location to the throttle body, as they were blocking a lot of air from the condenser, and therefore the radiator. at the same time, i had my radiator cleaned at a shop, and installed a 160 thermostat.

i've driven it twice since then in stop-and-go traffic with the a/c on, and it never got above 160. granted, it's been about 73 and wet here the past couple days, but i'm tentatively declaring problem solved.

 

Okay guys here's my story and fix: First off I had r12 all leak out, so i retrofitted at a local honest shop, replaced the compressor(internal failure). As soon as I would run the a/c, the single fan would turn on, as i would drive down the freeway or in traffic temp would steady climb to 220+ until i got scared around 250 and turned off the a/c it quickly went down to 200. So I went out and did a cooling system flush, 180 thermostat and a new thermal switch(200 on, 185 off). Still had the problem, would slowly climb to 250+ on the freeway moving a good steady speed, then i would turn it off and quickly drop to 180. Found out just recently r134a freon works on lower pressure, did some searching and found out there's a pressure switch located on the a/c receiver/drier. I unplugged it and between the two prongs of the plug is a flathead adjustment screw. For a retrofit it must be turned counterclockwise at least 1/4 of a turn to compensate pressure. ever since then, my temp will go to 200 a/c on in traffic in 100degree f. weather and sit at 200. Problem fixed for me! I believe what was happening was the compressor was building too high of a pressure and making an increased load on the motor(or acc. drive system). I also was having poor performance and sluggish accel. and very minor driveability issues with the a/c on before, now its great! Lemme know if this helps you.

 

That's pretty helpful. I'm still using R12 in my car and have the same problems that you listed above. Was the initial setting for R12 and you are now using R134? I believe that the compressor is putting a heavy load on the motor and it even vibrates the belt tensioner. The tensioner may be bad, but the AC puts a very noticable load on the car.

 

Reading this thread answered a problem that I have been working on for the last two Months. I have replaced the radiator, hoses, thermostat, water pump, serpentine belt,cooler plugs and three set of plug wires and radiator cap. Still would heat up to the point it would melt plug wires from the inside on my 1988 RS w\2.8L V6 (250 degrees on stock gauge).
After making this adjustment I can drive in 110* heat and never go over 220 on the temp
gauge even in mountain driving. (my mr. Gasket radiator cap with built in gauge reads ten degree cooler than stock gauge in dash). So the car is running great, just as I was
ready to throw in the towel and buy a new 2011 Camaro 2SS. Oh well I guess I can use some of that $40,000 this saved me and buy a nice IROC instead!!!!

 

Interesting....If it works for you, stick with it. That adjustment screw changes the point at which the A/C cycles off. Lowering it (counter clockwise) means that the A/C will run colder before the compressor shuts off. This would mean the A/C is running for longer periods of time. Which should in theory mean the radiator will be running hotter.

The only way I can see that making the radiator run cooler would be if the lowering of the switch made it so that the evaporator starting freezing up. At that point, the high side pressure and thus temperature (condenser) drops down, as the system can't absorb as much heat when the evaporator coils are frozen. You'd notice this by the compressor never cycling off and visible white frost on the A/C lines when you opened up the hood (engine still running with A/C on)