So my heater blower motor stop working.  Here is what I have done so far to troubleshoot.  Ran power directly to the motor which tested fine.  I had a spare switch and tried it which didn't work.  I have power at the blower motor with the switch in line.  In the wiring diagram I see a relay but cant seem to locate it.  It doesn't appear to be the one on the passenger kick panel and only the horn relay is on the driver kick panel.  Any clues on where it might be hiding??  Any troubleshooting tips are appreciated.  Im a total noob at electrical which I think goes without saying. 

Thanks

What year wiring diagram were you looking at? Where did you find the wiring diagram? The 72 FSM wiring diagram omits the heater blower. The 73 FSM shows it.

Edited May 1, 20195 yr by SteveJ

1 minute ago, SteveJ said:

What year wiring diagram were you looking at? Where did you find the wiring diagram? The 72 FSM wiring diagram omits the heater blower. The 73 FSM shows it.

Its a 72, I am using the 73

On the 73, the accessory relay that supplies power for the blower motor is on the passenger side kick panel. I can't say that the 72 has it in the same place.

I also looked through the parts catalog to see if it might give a clue on the location. No luck there.

I ran an independent ground to the motor leaving the factory power wire in place and the motor runs, the switch however will not control anything.  I ran a power wire directly to the motor leaving the factory ground in place and the motor doesn't run. 

So I figured this one out.  I solved two issues at once actually.  My original Hitachi Radio went dead about the same time as the blower.  I didn’t think they were related but they were.  The ground wire that goes to the radio chassis ground also supplies ground to the blower switch, that ground was compromised.  Reconnected and problem solved.  I still never determined if the 72 has a relay for the blower.  My guess based on rolling around under this dash for a few hours is no.  

What is the color of the hot wire going to the switch?

2 minutes ago, SteveJ said:

What is the color of the hot wire going to the switch?

Red

There is a red wire that splices into the blue/red wire coming off of the wiper fuse. Now, is that the only red wire? I'm not sure

If it is the only red wire, the power for the blower motor in the 72 comes off of the wiper fuse. Would you mind verifying that for me? Pull the wiper fuse and see if the blower motor works. That could prove to be a useful tidbit of information. If that is wrong, the blower motor and radio are on the Air Con fuse, and there is a different red wire spliced into the blue wire coming off of the fuse box. Of course, if neither fuse kills the blower motor, that means there is an inline fuse hidden somewhere.

 

18 minutes ago, SteveJ said:

There is a red wire that splices into the blue/red wire coming off of the wiper fuse. Now, is that the only red wire? I'm not sure

If it is the only red wire, the power for the blower motor in the 72 comes off of the wiper fuse. Would you mind verifying that for me? Pull the wiper fuse and see if the blower motor works. That could prove to be a useful tidbit of information. If that is wrong, the blower motor and radio are on the Air Con fuse, and there is a different red wire spliced into the blue wire coming off of the fuse box. Of course, if neither fuse kills the blower motor, that means there is an inline fuse hidden somewhere.

 

There was a inline fuse going to the blower motor.  Mine was in really sad shape so I replaced it with a spade clip style inline. 

So it is likely spliced off of the blue/red wire coming off the ignition switch before it gets to the fuse box. I'll have to test that if I can get my hands on a 72.