Well I drove my truck for the first time in a few weeks and found the a/c now only works at idle. When I start driving it just quits blowing cold air. WHY? Can you lose refrigerant and not have a leak? My dad bought a car when he got it the a/c worked good he let it set for a year before he started driving it and the a/c no longer worked. He had an a/c shop work on it and there machine is all auto so if there is a leak it wont put in refrigerant it took 2.5 pounds been working fine since. But like I said my a/c is ice cold when idling but gets warm when driving. I have one of those gauges from a a/c can from a auto parts store and it said it was in the good range but who knows. What would you all say it is?

 

I just went out and hooked that gauge back up at idle the low side is at about 30-35 psi. When i bring up the rpms the gauge goes up to about 40-45 psi or so and the compressor kicks out. What would cause this?

 

I hope there are some a/c guys around on the forum. I think I have found the problem but don't know. I am thinking it is the high pressure switch. But don't know if I can change that without recharging the system. Is there a valve under that? I hope someone on here knows something I really don't want to have to call the a/c shop.

 

I am having the same issue. Works fine at idle but give it any gas and the clutch disengages.

 

same here it was working fine before I got my new cummins now after setting it stopped working. I cant complain to much nothing has been done to the a/c system since 1996 when the truck was totaled. I hope someone can help us out!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Any chance it's overfilled? Do you have a gauge set that shows the high pressure side?

 

I know on mine, as long as the compressor is engaged the pressure reads about 35 psi which is supposed to be about spot on. But when you apply gas the clutch disengages the compressor and pressure spikes to the high side. It happens so quick though that I havent been able to decide which is taking place first, is the pressure spiking causing the compressor to shut off, or if its the compressor shutting off that is making the pressure spike. And if its the later then why is it kicking off?

I know on my last truck I had a issue with it staying on and i ended up putting a jumper wire on the plug coming out of the top of the dryer and that worked for a while. But I would like to fix this correctly.

It sounds like our issues are caused by the same problem. I only have a gauge to hook up to the low pressure side. I actually have a video of it posted in my thread. What would I be looking for on the high side?

 

Got cut off on the phone! Lol. Anyway I had a similar problem on another vehicle I had and it was an improper air gap on the clutch. High pressure switch sounds like it could Well be the problem also.

 

I know its not overfilled because it had been working fine since 96 and no one has added any. I only have one of those junk gauges that come with a a/c repair kit that my uncle had.

 

Can that be replaced without loosing charge?