Blower motor troubleshooting

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Mar 31, 2015 | 02:06 PM

vettman

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Tuned

Joined: Jul 2001

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Blower motor troubleshooting

Earlier today the blower motor/fan quit. I've verified that it's not a fuse issue. Is there some way to determine if it's the switch, or the motor, before I start the repair process. I kinda believe it's the switch because the fan had not been "acting-up" or making weird noises. Any ideas for the next step in troubling shooting would be appreciated.

Thanks

Mar 31, 2015 | 02:15 PM

greentruck72

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Joined: Feb 2015

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From: south east kansas

get a test light and start testing conections, how old is the motor, how old is the switch, personaly i have never had this problem. a test light is a good idea when you are trying the switch as well.

Mar 31, 2015 | 02:27 PM

vettman

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The truck is 39 years old; the switch was replaced once, 20 to 25 years ago. The blower motor is original. I know how to test circuits; just hoping to be able to do so without disasembling anything. I basically want to determine if any power is getting to the blower motor. Can this be done under the hood, or will I have to go under the dash? I believe there is also a resistor and/or relay in the circuit between the swich and the motor windings.

Thanks for replying

Mar 31, 2015 | 02:38 PM

bkaul

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Joined: Aug 2010

Posts: 1,761

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From: Knoxville, TN

There are resistors (mounted in the heater duct) to reduce the voltage for low/medium fan speeds - if there's a problem with these, the high speed will still work as it doesn't go through them.

If you don't have A/C, the back of the blower motor is exposed under the hood - pretty easy to get to the wire on the back and check for voltage there when it's turned on ...