A/C Not Engaging

[siffsiff]

I have a '99 Tahoe and the A/C compressor is not engaging. I have been reading the threads here and have done the following:

1. Checked the low pressure input and it reads about 30 psi
2. Jumped the wires connected to the low pressure switch and the A/C engages but the air is still hot. When I disengage the dash A/C switch the A/C disengages so I assume that is working okay
3. I replaced the low pressure switch and still no engagement (as expected due to #2)
4. I checked both fuses and they are good

Any thoughts on how to proceed next? Any suggestions appreciated!

Thanks in advance.

 

[Mayhem]

Make sure the connection plug to the ac unit is good with no frayed wires and clean.

 

[lesterl]

30 PSI with the compressor not running is near empty of freon, you probably need to charge it....

 

[MarkD51]

More than likely you have a refrigerant leak somewhere. All line fittings might look fine. A common culprit is the compressor itself. See any evidence of oil on the compressor housing?

 

[lesterl]

When is the last time it worked? I have had issues with the service ports leaking also..... I like to run some UV dye in when I charge a low one so when it is brought back low again later on I can look for the dye....

 

[siffsiff]

It turns out the Schrader valve was leaking so it was in fact low on refrigerant. I did take it to a shop and they ended up having to replace the complete hose assembly. Thanks for all your guidance.

-Steve

 

[lesterl]

Yup, low side was leaking, replaced many of those, also the high side from time to time.