HVAC not working properly

1993 CHEVROLET 1500

300,000 MILES • 5.7L • V8 • 2WD • AUTOMATIC

SHOVELHEADMOBY78

MEMBER
1 POST
FOLLOW

Truck listed above is a Cheyenne. with key off i can hit a button on the heater and fan comes on. something is draining the battery so someone put a disconnect at the battery. when you throw the switch the blower fan comes on. you can pull the fuse by drivers left knee and the fan speed gets higher. i have looked under the dash and no bad wires that i can see. i jumpered the A/C compressor and it wont come on.

Jul 18, 2020 at 10:01 PM

ASEMASTER6371

CERTIFIED EXPERT
52,796 POSTS

Good morning,

There could be several reasons for this issue.

There are relays for the blower motor. I attached the locations for you. Disconnect them and see if any of them shut the motor off completely.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Also, a bad ignition switch would cause this as well. If it is providing power when it should not, then this could be the issue. No power is to go to the control head unless the key is on.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

Images (Click to enlarge)

Jul 19, 2020 at 4:31 AM