I was driving my Tahoe to the shore yesterday with the a/c on which is very cold my fiance felt it was a little too cold for our baby so she turned up the knob on the climate control a little and hot air stated blowing through the vents! We made it down the shore I checked the fuse, relay and see if line was empty. Fuse and relay were good, line seem to have some but not sure how much. Later that night before leaving I turned on the Tahoe and the a/c was cold again, compressor was working properly but then we turned up the knob on the climate control again and hot air blew again. After that I inspected the compressor and it was still spinning but did not stop to cycle as if it would when cold air came out. Could it be low on charge? Both pulleys on the compressor spin when the cold air is blowing the frontpulley stops and spins, when the hot air blows the pulley just spins unless I shut the a.c buttin off...