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914World.com _ 914World Garage _ Need electrical help
Posted by: ww914 Mar 31 2014, 03:18 PM
I am in the process of determining why I don't have potential to my heater blower motor. I know the motor works because I hot-wired it to test it. Using the Haynes manual electrical diagram, I have traced all the wires (I think) and where they go on the relay board, the blower lever and checked the fuse on the fuse block under the dash. The diagram shows S13 as a fuse on the regulator panel. Anyone know where this fuse is located? If you look closely at the schematic it shows that connection T14/14 is north of the fuse, which tells me that the fuse must be somewhere on the relay board. Any help on this would be greatly appreciated.
Posted by: Dave_Darling Mar 31 2014, 05:42 PM
That's one of the fuses on the relay board--the rear-most one, it looks like.
The circuit goes like this:
Fan gets ground all the time on the brown wire. It gets +12V from the appropriate relay--the rear-most relay. The relay sends power from the rear fuse on the relay board to the fan when the relay is activated.
The relay is "activated" by having one of its switching pins at +12V, and the other grounded. The +12V is supplied by the same circuit that powers the coil, and that is hot when the key is on. The ground is supplied by the switch under the heater lever.
So, if the key is on and the switch under the heater lever is grounded, the relay should close and take any power that's coming through that fuse and send it out to the fan.
The most common failure points are:
- No fuse or the fuse is blown
- The switch under the heater lever has failed or is not connected
--DD
Posted by: Tom Mar 31 2014, 05:44 PM
Warren,
The heater blower fuse is the rear fuse on the relay board. Your heater blower relay is the rear most relay on the relay board.
Tom
Posted by: ww914 Mar 31 2014, 06:07 PM
Warren,
The heater blower fuse is the rear fuse on the relay board. Your heater blower relay is the rear most relay on the relay board.
Tom
Thanks guys. Since I whined, I found a good schematic and found the fuses. They are both good and I still don't have 12v to the heater fan. Oh, I did change the relay just to test and I grounded the heater lever solid. So, I am still searching. Well, who needs heat, except I just spent a fortune on Tangerine headers and a heat exchanger.
Posted by: The Cabinetmaker Mar 31 2014, 07:34 PM
It's called an auxiliary fan. It pushes air at idle. Once your moving at higher than idle the heat works.
Posted by: ww914 Mar 31 2014, 07:57 PM
It's called an auxiliary fan. It pushes air at idle. Once your moving at higher than idle the heat works.
Ummm? So, I really don't need the fan at highway speeds?
Posted by: Spoke Mar 31 2014, 08:18 PM
They are both good and I still don't have 12v to the heater fan. Oh, I did change the relay just to test and I grounded the heater lever solid.
Did the relay energize when you grounded the heater lever? If so, how did you check it?
I had a heater lever that did not ground the wire and didn't turn the fan on. Had to disassemble and clean the lever to get it to work.
Did you check for 12V on both sides of the fuse? If you have 12V at the fuse, remove the relay and check for 12V at the appropriate plug pin.
Follow the voltage and you will find the issue.
Posted by: cary Apr 1 2014, 08:30 PM
One more thing. Take the relay board out and flip it over. After 40 years the tar breaks down and the contacts push out thru the tar. Maybe you lost one leg.
Posted by: ww914 Apr 2 2014, 12:24 PM
I am in the process of determining why I don't have potential to my heater blower motor. I know the motor works because I hot-wired it to test it. Using the Haynes manual electrical diagram, I have traced all the wires (I think) and where they go on the relay board, the blower lever and checked the fuse on the fuse block under the dash. The diagram shows S13 as a fuse on the regulator panel. Anyone know where this fuse is located? If you look closely at the schematic it shows that connection T14/14 is north of the fuse, which tells me that the fuse must be somewhere on the relay board. Any help on this would be greatly appreciated.
Well guys, I would never rat on someone else, but since it is me, here goes:
When I thought the problem was electrical gremlins and the problem simply could not be fixed, the magic light came on. I had the relay in the wrong hole. Geez, it works good when the 'lectric flows where its suppose to.
Posted by: The Cabinetmaker Apr 2 2014, 12:43 PM
Every man makes mistakes. A bigger man admits his mistakes and learns from them.
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