Please help troubleshoot my A/C

[brianinswfla]

Hello all,

About 1 1/2 weeks ago I got my A/C refilled with R12 and replaced the pressure switch. The A/C worked great for 1 week then developed a problem cooling at idle. Going down the road it cools fine but at stoplights, etc it starts warming up considerably.

I took it back to the shop but they weren't much help. It's still charged and the compressor seems to be running properly.

If I rev the engine up to around 1700 RPM's the A/C starts cooling properly. Tried this at a red light. The lady in the minivan next to me looked at me funny but what the heck. I had to test it.

I don't know much about A/C systems anyway and this one has me baffled. Any suggestions would be appreciated.

Thanks,
Brian

 

[illwood]

If your car is a 1997 GT as listed in your signature, shouldn't it have R-134a for refrigerant, not R12?

My 1994 GT has a R-134a system factory.

Could there be something where the acutator for your heater core is failing and at idle, the AC isn't enough to overcome the heat from the heater core? Just a thought.

 

[brianinswfla]

Sorry about that. I probably updated the sig as you were replying. I have a '92 LX now. The '97 is long gone. It's been awhile since I posted here. It is R12. Once again, sorry for the confusion.

 

[PuterAmI]

You have a problem with your fan clutch. Replace it with a Police Special from PPI.

 

[brianinswfla]

You have a problem with your fan clutch. Replace it with a Police Special from PPI.

I would have never thought to check that. After reading your post I went out and looked at it. Obviously I'm no expert so I checked on the internet for ways to check it and here is what I found. It spins about 1/4 turn with the engine off and hot. I couldn't detect any play while grasping from both sides. There was no obvious evidence of leaking fluid. Does this sound normal? If so, can it still be bad even though it doesn't appear bad?

Thanks,
Brian

 

[PuterAmI]

Yes, it can. I have had two like this. A new clutch (thermostatic) will make a nice roar when you first start the car. After about 45-60 seconds, you should hear it die down.

If that is not the case, replace it.

Think about how, why, and when a clutch fan works. The fan is only needed when the car is not moving. After about 35MPH, the fan starts to become a hindrance. Hence the clutch fan.

Air drawn through the A/C condenser (radiator looking thing in front of the radiator) is how the heat from the refrigerant is taken away. Low air flow, low heat convection, and your A/C does not work as it should.

 

[brianinswfla]

Thanks for your help. I'll have to get my hands on a new one and cross my fingers. I'll post back to this thread once I do and let you know if it worked.

Thanks again,
Brian