Any GMC HVAC guys on here?

try duramaxdiesels.com

like you said, without the proper equipment its a crap shoot
 
We got gauges last night and checked pressures-high and low side are almost exactly equal. Dan thinks its a weak compressor or effed up orifice. Trying to diagnose before wasting money at a shop
 
Does it have a filter dryer on it? Check your temperatures on the inlet and outlet. Could be clogged up.
 
B.A.Ram said:
Now you're getting technical Travis....
Click to expand...

I just laughed so hard!!! Honestly, I've never messed with the air conditioning on any vehicle I've ever owned. A filter drier will look kind of like a big inline fuel filter.(or at least it does on residential units). Do you remember what the pressures were on your gauges?
 
Equal pressures don't happen with restrictions on a flowing system.

From my Not-So-Smart phone
 
I chased an AC issue for a very long time. Paid several guys to try to fix it and nobody was successful. I finally figured out what was wrong when the unit in the dash started smoking. I replaced that and my AC worked flawlessly
 
Most common is low charge, low psi cycling switch, temp actuator, or compressor. When the gauges are hooked up make sure the compressor clutch is engaged and turning.
 
TravisG said:
I just laughed so hard!!! Honestly, I've never messed with the air conditioning on any vehicle I've ever owned. A filter drier will look kind of like a big inline fuel filter.(or at least it does on residential units). Do you remember what the pressures were on your gauges?
Click to expand...

95 high/100 low
 
6.6lEater said:
Most common is low charge, low psi cycling switch, temp actuator, or compressor. When the gauges are hooked up make sure the compressor clutch is engaged and turning.
Click to expand...

Compressor engages but it seems to short cycle - all controls work it just won't blow cold. Already fixed a blend door issue and a thermistor? that would impact whether or how fast the fan would blow. Truck isn't blowing cold on one side or not changing fan speeds. It just blows warm air across the board. Appears to have the proper charge with no leaks. Compressor will only stay engaged about 1 second whether we bypass the low pressure switch or not. Thank god it's not mid August....
 
Diesel Dan get your azz in hurra and talk technical things and chit
 
Im here but I'm eating....


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B.A.Ram said:
95 high/100 low
Click to expand...

High side is way too high and low side is way too low. Depending on humidity it should be around 40/340. My guess is a bad compressor, not pulling the low side low enough and pumping the high side high enough.
 
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