Heater motor stuck on '11'

[72T]

The passenger side under dash heater blower is stuck on in my 87. Any ideas as to the best way to trouble shoot? It's da*n hot coming out of there, but I'd like to get a better answer than simply unplugging it. Any help appreciated...

[wwest]

Originally Posted by 72T

The passenger side under dash heater blower is stuck on in my 87. Any ideas as to the best way to trouble shoot? It's da*n hot coming out of there, but I'd like to get a better answer than simply unplugging it. Any help appreciated...

Engine blower also..?

[72T]

Good question. I just assumed that under dash blower had its own power to pull the heat through. But does it first have to come through the engine blower?

[darrin]

They both engage together, so a good first step in troubleshooting would be to determine whether the circuit's being activated or if a short is causing the footwell blower to engage

[scarceller]

under dash heat blower? Not sure what this means? the 84-89 cars have heat blowers only in the footwells right and left side directly in front of the car door hinges. When you say "Under Dash Blower" are you really referring to the foot-well blowers?

Both of the foot-well blowers are wired together in parallel, so if the RHS is on so should the left. Your description implies only one of them is on which likely also means the other is having issues.

Also, by design the front blowers can not be on without the rear engine compartment one also working. Can you verify what the rear one is doing.

[scarceller]

This may help:


The 2 front blowers are in the lower left, notice the relay that feeds them. This relay could be bad and fused closed. Try pulling this relay it's located in the front trunk area, not 100% sure where.

[72T]

I'm at work and will have to check the rear blower later today. The heat is coming from under the dash on the passenger side near the center - where there are vents, or I can adjust the red knob on the control panel by the radio and make come up the passenger side at the windshield. And it is very hot, which at first made me think it was blowing through from a heat exchanger, but that doesn't appear to be the case.

[scarceller]

Are the orange heat levers between the seats up or down? They need to be fully down to cut the heat. Even if they are down you need to double check the heater flap valves under the car above the transmission to be sure they are in the diverter position so that any heat coming from the heat exchangers is diverted below the car and not into the cabin. Look at the front of each exchanger and they have a duck pipe that connects the exchanger to the diverter valve. Double check the valves are in the position to divert the heat to below the car.

[JMP]

I had the same issue with my '89 Carrera.
It ended up being the cable from the lever to the heat diverter/flapper (I know, not the technical term) was broken at the Flapper. Host carries cable if needed.

[72T]

Thanks for the help everyone, great tips all around.

And yes, everything that is supposed to be off is off, as far as levers, but the cable could well be the problem. This all started when I ran the heat full boom heading to the 12 Hours with the top out, so I may have stretched something...

[rusnak]

you might locate the blower relay (silver box) in the engine compartment. See if you can separate and clean the relay contacts.

[bdisco]

^ might help?