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Friday, February 22, 2008

How Do I Check The Blower Operation on my 1999 Chevrolet Tahoe with Auto A/C?

How do I check the blower operation on my 1999 Chevrolet Tahoe with auto a/c?

1 comment:

Sparky said...

You will need to remove the black trim panel under the glove box area to access the blower motor and blower motor control processor. First turn your ignition switch on and place your hand on the blower motor. Next turn your a/c on with the fan switch adjusted to low blower check to see if you can feel the blower motor turning. If you can adjust the speed up slowly and see if you can feel and increase in the blower speed. Assuming that you cannot, you will next need your voltmeter. Place the leads on the black + and purple- wires at the blower motor connector you should have voltage. Next go the the blower motor control processor and check for power and ground on the red + and black -. You should have 12 volts. Now place your positive lead in the smaller purple w/ white wire and your negative lead in the black wire (in the 3 wire connector). Monitor voltage as you change blower speeds up and down. You should see a change in voltage as you adjust the blower speed control switch. If you do see a voltage change simply place the blower speed setting to high wait about 5 - 10 seconds and firmly tap on the blower motor with the palm of your hand (make sure you will not hit anything that will hurt you). If the blower comes on at a high speed then the motor is bad. If it does not, then the blower motor control processor is faulty. In the event that you do not have a varying voltage on the purple w/ white wire while adjusting the blower speed then the control head is probably bad, but it really should be checked with a scan tool like the GM Tech 2.
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