A/C Pressure

GUNNERGARIDEL

MEMBER
2002 GMC SIERRA
6.0L
V8
2WD
AUTOMATIC
316,000 MILES

I just replaced the A/C compressor in my truck listed above 1500hd. I also replaced the accumulator drier and the liquid insert [forget the name now] along with the high-pressure switch on the back of the compressor.

After I added Freon, I ran a diagnostic check with the A/C manifold gauge set.

With my A/C set on MAX and recirc, the gauges read 90PSI on the Low Side and 15 [yes, 15] PSI on the High side. What bothered me most though was when the compressor kicked on, the low side pressure decreased but the high side pressure did not change.

Obviously, I did something wrong or installed something incorrectly. Please give me any advice as to what I should check or where I should go from here?

Dudley "Gunner' Garidel
Baton Rouge, LA

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,244 POSTS

Hi,

For the pressures to be off that far, it sounds like the compressor you got is bad. By chance, is it a remanufactured compressor?

Did you replace the liquid line from the evaporator or are you referring to the orifice tube? If you feel the liquid line between the condenser and evaporator, does it get hot?

Take a look through this link. It explains common problems.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Also, here is a link that provided directions for replacing the compressor. Take a look through it to see if anything was missed.

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Let me know. Also, let me know if this is a remanufactured compressor. My first thought is the compressor, but you could also have a plugged orifice tube or expansion valve

Let me know.

Take care,

Joe