Hi,
Here is how the system works. Power to the relay is from a 80-amp fusible link in the fusible link box mounted on the battery. The relay receives power when the key is on from the ignition. When that happens, the relay closes and allows power to pass through fuse 20 under the dash and directly to the motor. (Both the relay and fuse are in the interior fuse box on the left side, under the dash.
So, the fan motor has power when the key is on if the relay and fuses are good. For it to run, it needs the circuit completed to ground. That is provided through the switch inside. Based on speed setting, power to the switch goes through a resister which changes the motor speed. So, either we have a bad fuse, relay, switch, motor, or ground.
The quickest way to check would be to check fuse 20. When you check it, make sure the fuse is good and it has power to and from it. Here is a link you may find helpful:
https://www.2carpros.com/articles/how-to-check-a-car-fuse
If the fuse is good and has power, go to the blower motor and check the yellow wire for power. If it has power, check the blue wire for continuity to ground. Note, the blower motor switch must be on. I would suggest placing it on high speed.
I attached pics below for your reference. Pics 1 and 2 are the wiring schematic for the blower motor. You can see where everything goes. The last two pics show fuse/relay locations.
Let me know if this helps or if you have other questions.
Take care,
joe
See pics below.
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Monday, July 18th, 2022 AT 1:39 PM