I have a 1995 GMC sierra and the heater ha quit

SOURCE: 2003 GMC Sierra heater Blower wont shut off

My 2003 Sierra's blower came on by itself in the garage while I was sleeping and ran the battery completely down. I had to replace the blower switch located under the glove box next to the blower at the bottom of the right corner of the dash. The switch is in front of the blower and held in by two screws. Disconnect the two wire connections. This is a "dealer only" part and cost me 65.00. Also check the wire harness with seven wires connected to it for melted plastic. It will be marked "ABCDEFG". If it has melted, you'll need to replace it. Pay attention when reinstalling either part, that the wires "ABCDEFG" match the switch in that order.

SOURCE: 2000 gmc sierra 1500 5.3 v8. a/c heater control problem

your heat/cool and vent selection options are controlled by engine vacuum through small clear tubes attached to the rear of your climate control interface. Other vehicles have small steel pull wires that operate the desired changes. You might try removing the trim and any fasteners affiliated with the interface/console. GENTLY pull outward and look to see if any of these tubes are pulled off or cut/damaged. Did anyone recently install a new stereo in the vehicle? If so, the vacuum tubing and or pull wires that change your outlets could have been damaged when the stereo unit was pushed into place. Hope this helps

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SOURCE: The blower motor in my 2005 GMC Sierra won't turn

passenger side under dash by blower there is a thermistor that is fried remove it from housing and replace

SOURCE: 1990 GMC Sierra 1500 pickup. Windshield wipers, Cruise Control

May want to look at replacing the wiper circuit board.It is located on the firewall adjacent to the wiper motor and has a some what square black cover with 3 torx screws and wireing harness pluged into the side.We had a truck that every time you washed it the wipers would stay on until it dryed out.You can try removing it and spaying it down with contact cleaner just watch the brease on the two contact tips.Well hope this helps.