I have a 2003 Suburban 5.3L. I recently had the engine removed and disassembled to have a rod bearing replaced. The AC systems was discharged and removed from the vehicle during this repair. A couple of weeks after getting the vehicle back I turned on the defrost when the windows were fogging up on a rainy day and noticed the windows were not clearing up as they should. When I raised the hood to check the AC compressor I noticed that the compressor was not engaged/operating. I called the repair shop back and told them the system worked fine before they removed & reinstalled everything. The shop told me it had nothing to do with the work they did and that my problem was an outdoor ambient temperature sensor. Seems awfully unlikely of the timing of a sensor going out as opposed to the shop not putting the vehicle back together correctly. They replaced the sensor, called me to say the problem was fixed and I picked the vehicle up. When I turned on the defrost the AC compressor did not come on! It's winter right now and is too cold for air conditioning, but I know the compressor is supposed to come on when you select defrost to help dehumidify the air inside the vehicle. Does anyone have any idea what the shop could have done? The AC clutch connector is plugged back in and the system was recharged and I do not know what else to check. I feel that the repair shop is responsible for this problem but that they do not know what they did (or didn't do). Does anyone have any thoughts or input as to what the shop did not do correctly?

 

Welcome to the forum.

FWIW, the A/C compressor doesn't operate when ambient is below about 40*.

Not sure why they didn't just remove the compressor from the engine and get it out of the way when they pulled the engine.

 

Thanks for the reply. I also wondered why the compressor wasn't just unbolted and moved out of the way. After posting this I went through my owner’s manual again and it states, just as you say, that the compressor will not engage at temperatures below 40 degrees. I will have to wait until the temperature is above 40 to know if the problem is fixed. I was visiting family near Arkansas over the weekend and the temperature was close to 60 and the compressor still did not engage when I checked it. Hopefully the problem is now fixed but I will have to wait for warmer temperatures to know for sure. It just seemed very coincidental with the timing of everything.

 

If the temperature is below the temperature at which it should operate, the light in the compressor button on the control will flash when you push it and then stop flashing which indicates the compressor did not come on.