Air Conditioning compressor problem

[rolfsent]

My Air conditioning in my 1999 Denali has not worked since I purchased it back in January, so it finally got hot enough for me to check it out. I tried to put refrigerant in it and the compressor wouldn't turn to let any in, I jumped the compressor with a small piece of wire and it started turning and was charging. The air coming through the vents started getting ice cold. After I used one can of refrigerant I plugged the compressor back in and the compressor stopped turning. I can't figure out why the compressor only works when it's being jumped. I also replaced the relay that's under the hood in the fuse box. If anybody has any insight on what could be wrong your help would be greatly appreciated.

 

[psfr311]

bad connection to the compressor?

 

[SunlitComet]

there is a pressure sensor that is malfunctioning forbidding the computer from activating the relay or the pcm is not receiving the request from the hvac module requesting the compressor to be used.

 

[rolfsent]

there is a pressure sensor that is malfunctioning forbidding the computer from activating the relay or the pcm is not receiving the request from the hvac module requesting the compressor to be used.

Where is this pressure sensor? And how do I fix it?

 

[SunlitComet]

you have about 2-3 of these switches. but first since hvac modules have a tendency to go out on occasion check to see if 12 volts is being output from the light green wire from vertical wire harness on back of module when the a/c is turn on and the little a/c light is on.

 

[robhenry2990]

i have the same problem on the vert wire harness i have 3 green wires 2 dark 1 light 1 dark and light are 12v and the other dark is 6v i didt press any other buttons so i dunno what the other green is. where are the switches at? and how can i test them?
so i just reread the post and seen that you said light green lol