# blower motor



## 68GTO4004Spd (Jun 19, 2008)

My blower motor (heater) is not working this is a non A/C car. I really suck at diagnosing electrical problems so I need some help. How do you test the blower relay? Is it common for it to go out? How do you test the motor? Can you bring power directly to it? Is it very likely the switch went out? I'm pretty sure the fuse is working.


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## geeteeohguy (Feb 2, 2008)

You need a test light. Auto stores sell them. You connect the clamp end to a ground, and you can stick the pointed end on the electrical connection you want to check. Relay's can fail, and so can switches. Usually, you'll lose one or two speeds as the resistor in the fan switch goes bad...not the whole thing. I would turn the switch on HI (this bypasses the resistors in the switch) and see if you get a lit test light at the blower motor connection at the motor. If not, see if you get a lit light at the switch. If not, keep going back towards the fuse panel, checking wires, connectors, etc, until the light illuminates. Fix the open circuit and you're good. It could also be you have power, but the blower motor is seized up or defective. You could do more exacting voltage drop and load tests, but for a beginner, a simple test light will get you going. Hopefully, Professor Bear will chime in with additional information.....good luck!


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## 68GTO4004Spd (Jun 19, 2008)

Thanks Geetee, I don't have a test light, can I do all those tests with a multimeter? It has amperage, voltage and ohms. Also can I run a jumper wire from the battery to the motor or is thar too much amps or volts for the motor?


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## jetstang (Nov 5, 2008)

Geeteeohh is right, but you can run a hot from the positive on the battery directly to the motor, if it spins fast, motor is good. Then it's in the wiring. If it doesn't spin, loosen and move around the ground and try again. If it doesn't spin, the motor is bad, if it does, wiring is bad.


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## 68GTO4004Spd (Jun 19, 2008)

Ok I think I am following you. A couple of questions, you said connect the test light to a ground, can that be any ground or does it have to be the ground wire on the blower? Just to make sure I understand, if I put the test light on the switch and it lights, but doesn't light at the blower, that means the relay is bad?


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## 1970 Lemans (Jul 25, 2009)

Does a non A/C car even have a relay? 

Looking at the wiring schematic for 1970 (maybe different for 68?) the control switch (one off position, then low-med-high setting) goes directly to the resistor block which introduces decreasing resistance for increaring speed setting ... no blower relay. For 1970, A/C cars have a relay that routes power for the high speed only, but the power otherwise routes through the resistor block (no off, low, med-low, med-high).

Also, I didn't think the switch itself had any resistors in it, though you can get failure at the switch due to the wires frying there.

IMO FWIW


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## 68GTO4004Spd (Jun 19, 2008)

Got it narrowed down to the resister, thanks for the help guys!


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