Question guys....... when i use my A\C for prolonged periods of time say more than an hour, the blend doors seem to almost close and no air comes out of the vents or defrost pockets untill i take the A\C off, has anyone had this problem before? After the A\C has been off for ten minutes or so you can switch it back on and it works fine for about an hour and then it does the same thing.

 

Sounds like your evaporator is freezing up. Perhaps your low pressure switch is not kicking out the compressor when the pressure drops too low. That will cause it to ice up and block air flow. When you turn off the compressor for a bit, it thaws out and starts flowing air again. Next time, leave the blower on and just turn off the a/c button and see if it thaws out and the flow returns. If so, your low pressure switch is not kicking out between 20 and 25# like it should.

 

I'm having a similar problem with my 02 2500, except mine goes on and stays on through the defrost vents. I can't get any air at all through any of the dash mounted vents.
I have the factory manual and I've reading it, (sec 24). There's a lot of stuff that needs to be checked, from the compressor clutch relay to the vacuum check valve. I suspect mine is in the blend door actuator because everything else seems to work fine.

 

kln4, I would concentrate on your blend doors. Looks like your system is defaulted to defrost.

 

Ok thanks lxman1, would having too low a pressure in the system do the same thing i'm wondering?

 

Yes it will,and I just noticed that my 08 has no low pressure switch to prevent this so I would suspect it is a little low of freon. Should be between 35 and 45psi on the low side.