2002 GMC Sierra AC blows warm

[GMGator1]

Hi, I have 2002 GMC Sierra and the AC worked intermittently for a long time and then just started blowing warm air. I purchased AC Pro and of course that did not work, I don't hear the compressor engaging but have been told it could also be a low pressure switch, any assistance on how to troubleshoot this and repair would be greatly appreciated, no AC is no fun. Thanks

[8.1HD/ALLISON]

Need to check pressures first. Or better yet evac and recharge to be sure you have proper freon charge. If it still wont work its time to diagnose electrical portion of system.

 

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[Doug_Scott]

If you intent on trying to fix this yourself, at the very minimum you need to get yourself a set of gauges to measure pressures in the system.

 

Before you added a can of refrigerant to the system, was there something in the system still? If not, it will take more than can to get the compressor to start cycling. Amount of refrigerant required should be shown on the a/c sticker under hood.

 

If the system was empty before putting the can in, you have a leak to find. Depending on the size and number of leaks, it may require more than one service to correct. I would take it to a reputable a/c shop and have it checked out. It may be cheaper to get a legitimate check done, that it is to just start throwing parts at it.

[02suburbanZ71]

Do you hear a hissing noise near the condenser at all?