ac issues

[toddy]

My ac won't blow cold when the truck is idling after it has reached operating temp. But once you get on the gas it works again. Any ideas? Low refridgerent? compressor going out? Any ideas

[toddy]

anybody got any idea

[jfines@cox.net]

That is a common compliant with an R134a system. The drop in air flow across the condenser has stopped when you do, thus slowing down the heat transfer.

But don't rule out other things, get some gauges and get a good reading. Low refrigerant can do the same thing to an extent.

With my truck when it is 110* out side at an idel, the temo in the air ducts go to 50* while driving it will drop to 35-40*. The system is new and properly charged.

[toddy]

Did some checking today. The pressure with the ac on full blast is 42 psi. When I turn the truck off I can here a slight hissing sound coming from one of the ac lines. when the truck is in park and idleing the air blows cold. Once the truck has reached operating temp and the truck is turning low rmps of no serious load such as WOT the air output slows and the temp of the air goes hot, hotter than the outside temp. Once I put a heavier load on the truck and the rpms raise the air goes cold again.

[kinghawg98]

the high or low press is 42? hissing is probably just equalizing pressures, no big deal.

air should shut down at WOT, thats normal.

do you see a mineral oil like substance on any of your a/c lines?

[toddy]

Originally Posted by kinghawg98

the high or low press is 42? hissing is probably just equalizing pressures, no big deal.

air should shut down at WOT, thats normal.

do you see a mineral oil like substance on any of your a/c lines?

Air blows cold at WOT and hot at cruising. No I dont see any oil on the lines. I put some dye in it today so I can check it with a uv light later tonite. The side you fill the refridgerant in was at 42psi

[bryan.d]

I'd check the air gap on the clutch on the compressor. Also sounds like your fan clutch (radiator fan) is not working. Does the fan free wheel when you shut the truck off? If it does it's prolly bad. hope this helps

[toddy]

What is the air gap that you speak of? No there is resistance against my fan. my trucks temps stay normal.

[bryan.d]

Its the gap between the clutch plate and the pulley. The clutch plate is the forward most part on the front of the a/c compressor. I'm not sure what it should be . To me it sound more like the fan clutch. It should have some resistance on it. Your temps would probabally be normal empty, but loaded it may run hot. I'm not real sure on a test procedure. Someone else may chime in.

[DJM]

My A/C is doin the same thing