Hello, I have a 2006 GMC Sierra 1500 5.3L Ext cab, the AC intermittently working. It will always work when I first start the truck and then blow warm air. It will blow cold shorter times during hotter days. The compressor is not running when it blows warm. I have checked the charge on the system and it is good. I have replaced the low pressure switch and checked the continuity is good. Not sure what the next step would be, the relay module or the High pressure switch? or icing up the line and needs purged? or the wire connection at the low pressure switch?
AC Intermittently Working
My initial thoughts would be to check the high speed fan and or the high speed fan relay. The system is charged and the compressor is cycling as it should. So lets look to make sure the fan is cooling the Freon in the condenser.
It may be possible that the Electronic Blend Door Actuator is not functioning properly which would only allow warm air to pass through vents. The Air Conditioning lines going into the firewall would be cold if this is the case. Most common to replace actuator.