1995 GMC A/C fan only works on high???
Two possible problems. First the Freon level might be too low to allow the low pressure protection switch from letting electricity get to your compressor's clutch. This is just a 'most likely' reason, there can be others.
But then you definitely have a problem with the heater resistor pack that is mounted in the heater's air stream somwhere behind the glove box. This device allows for low, and medium fan speeds but needs to be cooled or else it will melt and open up electrically. When that happens you 'loose' fan speeds except for high which is 12 volts direct to the heater motor.
This year GM pickups needed the HEPA air filter but did not have one so that all manner of hay trash, leaves and you name it would plug up the air conditioner evaporator inside the cab which in turn stopped enough air flow to the heater resistor pack which causes it to fail and you wind up with no DOT required defroster AND carbon monoxide preventing air flow into the cabin. There is law and how they avoided a class action suit is beyond me but you are looking at about a hundred dollars to replace the resistor pack and heater switch too.
You might have minimum success blowing the trash out of the evaporator backwards after you take it all apart, as a passenger when you kick the 'heater', that is right where you need to go to clean out the evaporator. It's only 1/2 inch thick and on the bottom of the pile.
If you have good air flow on high then you can disregard the blowing out of the evaporator and just concentrate on getting to the resistor pack - we just changed it with the switch panel to get it all done with in one shot. There is an outside chance that fixing the resistor pack/switch will return your compressor's voltage as well, there is no telling how that switch has it's failsafes integrated.
Jun 19, 2009 |
1995 GMC Sierra C1500