A/C blows colder when RPM's are up but not as cold at idle

[bucketman]

I was driving my '96 80 around this weekend and noticed that the A/C was not blowing very cold at idle, but blew colder when the RPM's increased. Any ideas? Compressor issue? Needs a recharge?

 

[richardlillard1]

When you're sitting at idle, less air moves over the condenser, making the AC less efficient.

A temperature increase during idle is normal, but can be exaggerated if the AC system is over or under charged. I would at least check the pressure readings and how the refrigerant level is.

If everything is fine, look into ways to get more air over the condenser at idle; either an aux fan or juicing your fan clutch.

 

[Howard705]

Think most do-compressor is running faster and so is the fan-which has to cool the refrigerant.

 

[Stevesnj]

Could be just a bad fan clutch.

 

[bucketman]

Thanks for the input. I'll check out the fan clutch and the charge.

 

[Nut430]

Fan clutch or blocked condenser.. Give condenser a wash with your garden hose. When the ac cycles on how cold is the suction line into the evaporator?? If not cold then system is undercharged.. Top up with gas..
Ben

 

[BILT4ME]

When you do AC, typically your testing is done at 2000 RPM now that there is enough flow through the system. That happens to be about 50 MPH for me when in top gear, w/ OD on. When I'm in traffic or residential, I downshift and hold it in a lower gear to keep my RPM up so my AC works better.

Also, use the "recirc" function and it will get colder inside.

 

[Nut430]

When you do AC, typically your testing is done at 2000 RPM now that there is enough flow through the system. That happens to be about 50 MPH for me when in top gear, w/ OD on. When I'm in traffic or residential, I downshift and hold it in a lower gear to keep my RPM up so my AC works better.

Also, use the "recirc" function and it will get colder inside.

If you have a good healthy system you should not need to "downshift and rev the engine". Keep looking for the problem..

 

[Dave 2000]

The engine should 'idle up' if the A/C is on, every time the compressor engages up go the revs only 50 rpm or so but they should rise.

I agree to the possible need for a recharge as well, and also while under there check the drive belt is not slipping, it can cause the same problem.

regards

Dave

 

[DieselDriver]

I chased a the exact problem in a different vehicle. Every part of the system was replaced one at time(dealer) charge of freon was always correct. In the end the compressor ended up being the weak link...

 

[Onefastrx7turbo]

Every car I've owned (10+) has had warmer AC at idle vs moving. This goes for electric and mechanical fan systems. I think it has to do with air flow across the condenser + A/C Compressor speed.

 

[Chris FJ80]

This is a challenge for me in AZ. I have installed both a CDS fan and upgraded clutch fluid. Much better now