2004 Yukon..A/C just blowing, not blowing cold

[mikemhp]

2004 yukon slt 175,000 miles
recently replaced computer and fixed transmission issue-
A/C was working great, now just blows regular air. not hot nor cold no matter where the temp setting is

any suggestions?

 

[OR VietVet]

First: Look to see if the compressor clutch is engaged during operation. Second: If it is not engaged attach gauges to check pressures in system. You can also touch the shrader valve and see if you get any pressure out of system. Third: If it is engaged then you may have an actuator problem or control panel problem.

My guess is you have a low/empty system or maybe a pressure switch that is not allowing the compressor clutch to engage. You may also have a wire disconnected related to your recent computer replacement. By the way, which computer? How soon after the recent work did this a/c problem show?

 

[mikemhp]

update- hooked up a relay bypass tester to the a/c relay in fuse box, air conditioning came right on.
swapped out that relay (#8866) with the same one next to it, the horn to test. a/c still didn't come on, and the horn still worked
????