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MagnusA MagnusA is offline
Registered User
Join Date: Oct 2014
Location: Sweden
Posts: 6
Engine compartment heater control module


I have a non-functioning heating on my 3.2 from 1984. There are many good threads about this that I have read on the forum but I can't find the logic on the heater controller to the left in the engine compartment. I have opened up that controller and when I push the relay to the heater fan it starts working. So now I need to check if the controller or something else is broken.

The controller has following terminals;
1. From the speedometer
2. Ground
3. 12V from fuse in engine compartment
4. Signal out to the footwell blowers
5. 12V output to the heater fan (but not on my car )
6. Same as 5
7. 12V from fuse
8. 12V from fuse
9. input from the auto heat, looks like this should have 12V when starter solenoid is on
10. Temp switch situated on engine on a difficult to reach position
11. From starter solenoid
12. 12V from fuse

As I understand it the heater fan has two functions;
1. Help to cool down the engine at low revs and thereby poor cooling from the big fan.
2. Spread some nice warm air to the coupe on chilly days (like in Sweden now)

The first point should likely be taken care of by the inputs 1 and 10 but what input takes care of the ventilation heat? 9 and 11 looks to have 12V only when starter motor is on so when normal running I think they are dead or is my wiring diagram wrong? I opened up the auto-heat box between the seats and it has 12V on the yellow cables when I start the engine but nothing after that.


Last edited by MagnusA; 10-26-2014 at 11:29 AM..
Old 10-26-2014, 10:56 AM
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