A/C will not come on for about first 10min. of driving. Auto or manual the A/C light will just flash four times and go back off. The refrigerent has been checked and is good to go. The low pressure switch checks ok too. When the A/C does finally come on it works great until I turn the truck off and then we start all over again. Any ideas?

Aaron Lail
Tru Dyno Sports LLC

 

No one has seen this? It's a climate control setup and seems to have a mind of it's own.

 

I haven't seen this yet. And at the moment I cannot think of anything to recommend. Drawing a complete blank at the moment. I'll paruse through my books tonight and see what I come up with. I am thinking it is a sensor failure, just don't know which one.

 

Update,

Dealer seems to think it might be the control head causing the problem. I don't want to shotgun this part because my cost on it is $240.00. I guess it makes sense though because when it works everything works good including the auto AC temps and fan speed. But when the AC won't come on and the light flashes it won't work in manual or auto. The fans and duct positions still work the AC compressor just won't come on and the AC light on the button just flashes four times and goes back off. Anyone have to replace their AC control head on the climate control systems?

Aaron.

 

Update,

Changed the AC control head (found a new one that I could try before buy) and this did not fix the problem! I don't know wth is wrong with it. Still flashes 3 or four times when you press the AC button. Seems to be getting worse though. It won't come on at all now. I have bypassed both pressure switches just to be sure. I have heard that the PCM could be the problem. Like maybe the AC is not allowing an enable due to WOT or something like that. Again, surely someone else has had this happen to them.

Aaron.

 

I don't know what is going on with this AC. I have checked all of the wiring to and from the Control Head, VCM, and everything else that the AC needs to operate. The VCM never see's an AC request signal so therefore it never comes on. If I ground the AC relay the clutch comes in and the AC cools fine. The pressure switches are all closed and working correctly. I have changed the Conrol Head with a new one. I'm about to pull my hair out on this one. Any suggestions would be great.

Aaron.

 

Has anyone seen this happen to them? I'm still dealing with this issue and spring will be here before I know it.

 

we are experiencing the same problem and was told that it was the control assembly inside vehicle. However we don't it is the climate control assembly. Instead, it might possibly be the ATC Power module because my brother in law took a look at it and said the wires connected we're too hot (possible short) he wiggled the wires slightly causing the fan to go on and off. Let us know what you find out. We will do the same.

 

could it be the compressor on its way out? maybe its just not kicking in fast enough so the blinking light shuts down... then when you try again its going? just a thought. i'll run this past a friend of mine for ideas...