A/C Question
 

I have a 2002 Chevy 1500HD crew cab. The a/c works fine going down the highway. If you are sitting still(at a light etc) the vents put out warm air then when you start driving its fine again. Any ideas?

Re: A/C Question
 

one or both problems
just low enough to cool driving and/or the cooling fan isn't working ,
some cars/trucks have a fan on the coil out in front.
don't get one of the cheap fill kits freon can be nasty to your body if a hose burst
a tech with gauges can tell the problem real quick .


ps with it idling with ac on see if the ac comp clutch is cycling both problems stated above can cause it to . if no elec. fans and cooling fan on water pump is pulling air thru the red. it prob is just low gauges tell fast jim

Re: A/C Question
 

Might also check to see if the outside of the radiator is clean of debris.

Re: A/C Question
 

I had the same problem a few years ago the clutch fan was bad. Replaced it never had it happen again.

Re: A/C Question
 

Thanks for the input guys.

Re: A/C Question
 

Quick and easy: Put a floor fan in front of the grille with the A/C on at idle. If insufficient air flow through the condenser is the culprit you'll see the vent discharge temperature drop real quick when you turn the floor fan on. I've had this condition caused by GM clutch fans that absolutely did not feel bad or slipping by hand.

Re: A/C Question
 

What are the vent discharge temperatures at idle? Going down the road?
Your truck has a viscous type fan clutch that really doesn't move a lot of air through your heat exchangers like an electric fan would. So, your discharge temps will be high @ idle. This was always a problem with a viscous type clutch. Any way, make sure the fan clutch is good. If it is good, make sure you have the correct amount of refrigerant in the system. Too much refrigerant and/or PAG oil will degrade A/C performance.