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Steeletj

Heater switch wiring questions

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I have pulled my heater box, cleaned the mouse hotel out of it and rehabbed it.  I bench tested the fan and it runs quite well for its age. 
Now I have the heater box reassembled and back in the car, but still no operable fan. I have power through the switch and to the back of the resistor on the green and brown cable. I am not seeing any power through the blue and white (might be gray) wire with the key in any position and with the switch in any position.  I am also not seeing any power on the three other wires on back of the resistor.  
 

When should I see power supplied to the blue and white wire at the switch?
multi colored wires are fused correct?  All fuses look to be good. 
 

What am I missing?  
 

Thanks in advance for guiding a rube. 
 

Tim

 

I am also trying to replace the seat back release cables in both my front seats. Anyone know where I can source something like these?

image.jpg

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(edited)

Have to ask.. is it grounded?First thing to check is always the ground,The box needs to be grounded to the chassisIMG_0724.JPG.

On my late model  02, the ground wire attaches to the driver side heater box mounting stud.

Its the brown wires with ring connector hanging down a little on left side of box.

Edited by tech71

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I have the grounds connected to the mounting stud. Two bundles of grounds in fact. But always best to double check. I’ll poke my head under the dash tomorrow. 

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You don't indicate your car's year.  If it's a 4 lever heater (73 and later), that switch is open to the elements under the dash and the contacts can corrode to the point where you can get a voltmeter reading at the resistor pack, but very little amperage--not enough to spin the motor.  If you do have one of those switches, while you're under the dash, run a doubled-over piece of fine sandpaper between the switch contacts and see if that helps. 

 

If you have a 3 lever heater assembly, it's something else as those dashboard binnacle switches rarely fail.

 

mike

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I dunno about the earlier cars, but for the >73 cars the resistor pack is on the ground side of the motor... there's one +12V  going direct to one side of the motor, the other side of the motor goes to the resistor pack, and then the 3 wires for the different speeds earth the other side of the resistor all switch to earth via the dash switch.

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So I took my coffee out to the car and followed your suggestions.   I cleaned the contacts at the 4 position switch.  I double checked the ground at the mounting bolt. I rechecked the fuse. I realized the white and blue wires are for the tiny dash lights and power up with the headlights.   Still nothing past the green and brown the back of the resistor.  
 

dlacey, your explanation of the switch being on the ground switch was helpful. I jumped a wire from the green and brown wire at wiring harness connector directly to the fan motor.   The fan works perfectly. All switch positions function. I think that means that I am loosing connection from the resistor to the motor on the negative side. 
 

The bad news is that I think I need to pull the box back out and open it up again to fix this.  I am not positive all my flaps were operating perfectly so now I have good reason to get it right.   Thanks for the help and I will let you know if I have success. 
 

Tim

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The box comes out more easily the 2nd time. Ask me how I know :D

 

You looked at the tech article for the refurb, right?

 

I have a saved version of that with the proper photos if you need, or search the threads I have posted it before. 

 

Thanks to ChrisB for the article.

 

Cheers,

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Success!

 

It was a bummer that I had to take it back out, but in the end I got the Bowden cable better adjusted and solved the wiring issue by making up a slightly longer wire to be sure it stayed connected during assembly. 
 

on to seat repairs. 
 

Thanks for the help.

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