TR2/3/3A Heater electrical connections

[dbenichou289]

So I have to hook up the heater motor now. While reviewing the service manuals I have, it shows the heater assembly as an option and only lists connections required. Sooooo, where and how do I hook this up? I have the heater knob mounted to the left of the steering wheel on the dash (I presume it is the heater knob as it is the last of the 'unmarked' knobs remaining with just 2 prongs on the rear).

Where do you all connect to find the power source? I presume it then goes through the knob, then to the heater. On a side note, the heater has 3 wires on it (one has a looped eyelet, the other 2 wires are open ended - so what goes where? A diagram would help tremendously.

And one more last stupid question....how does it work? Is the knob a rheostat where when you turn it on is comes on at a slow motor speed then speeds up as you turn the knob further? or something else?

 

[sp53]

There should only be 2 wires coming out of the top of the heater, one for ground with that loop that hooks to the firewall brace in one of the holes on that and the other wire the hot for the motor. Perhaps you are seeing the third wire as part of the loop for the potentiometer. The power source is sometimes in the harness a green wire dead ending by the fuel gauge in the harness waiting for the heater. Most of the gauges are mechanical, but I think I remember some heaters were hooked to the fuel gauge power, but not sure.
steve

 

[CJD]

The manual on page 12 of the Body section tells exactly how to hook it up. Power comes from the live side of the wiper switch on the center console, goes to the heater rheostat, then to the heater. The ground wire has an eyelet that goes to the left side dash support under the screw mounting the heater unit to the support. There is frequently an inline fuse between the wiper switch and the rheostat.

 

[DavidApp]

I wired the heater through a relay that is controlled by the ignition switch. It prevents me leaving the heater on and coming back to a flat battery.

David

 

[Graham H]

I think the first movement when you turn the knob is full speed and it slows as you continue to turn it.

Graham