2001 GMC SIerra 1500 A/C stopped working. Won't blow on any settings.
Relays will DROP out with an under voltage condition...suspect the ground connection 1/0 battery cable to chassis has corrosion making it a "semiconductor" burns itself to deliver the required 300 cold cranking amps, but settles into a "brown out" condition....take off that bolt battery black cable as it attaches to ground and wirebrush it shiny...and put it together...just test the voltages AT the relay buss~ ....insufficient to pull a relay contact....get a NEW battery~
Have you checked the AC Serpentine belt? I had mine break and didn't know it. I replaced the belt and the AC worked. I have a 2005 GMC Crew cab.
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