Heater motor and polarity (mk 1 and 2 cars)

The car was converted to negative earth in the 80s, by the previous owner. The heater motor wiring has not been reversed, so it's running the wrong way I guess. At least the heater in my blue one, which I eventually switched the heater wires on, runs much faster. I suppose this effect.

To be honest, I used to be of the opinion that a clock, radio and some gauges would be the only things that would need attention during a polarity change.

Don't remember the details, but I think there is one connection at the top of the heater, where two wires enter. A green(current supply) and a black (earth) wire. In addition to reversing them, you also have to switch the wires on the heater lever panel, or isolate them and install a switch for the heater.

Forgot something?

Tommy

Had a look at it. Ok, it does not go faster but blows more air when it runs the correct way, as far as I can tell.

I reversed the black and green wires going into the heater motor. There are also two wires at the lever swith. One is grounded by the lever (black). Connecting these two wires starts the heater motor. I connected these two wires to a separate switch which now starts the motor.

Well, it sure blows more air now. I have not tested if the engine still runs on for a few seconds when i turn the ignition off while the heater motor is blowing.

If it does, is this really a problem? Does it play up the ignition circuit? Perhaps it's what makes coils warm? LOL...

T

Getting the motor running the right way will certainly make the fan more efficient, even if it's running at the same speed. It's a centrifugal type fan, which is actually quite efficient, but will only move about 30% of the air it could move when running in reverse.

I'll have a read through the wiring diagram later and see where the circuits are meant to be routed.

Chris.

Thanks Dave! I never really got to the bottom of it. The blue one has been standing for over a year now, and I'm planning to get into it during the winter, as I now have a well functioning one to compare everything with. The white one has now been my daily transport since April, with very few problems!

Looking back, perhaps the hot coil was not a problem, as the white car's coil will also get hot after idling for a time. It runs beautifully however. I'm more to the theory that I never got the carburettor settings right.

Regarding the running on when heater runs, it actually still does it after I fitted a separate switch and reversed the wires (I can tell for sure it's running the correct way now. I checked the blue one today too, and the same thing still happens to that one! Strange!

I'll look into the green wires. At least the heater motor, the brake lights and possibly the wipers and indicators are fed from a connection at the voltage stabilizer relay behind the speedo. I'll get into the wiring diagrams again, and possibly arrange everything similiar to mk 3 cars.

Also, in the dark, I notice the charging light glows dimly when operating heater or brake lights, but not when switcing on head lamps etc. BTW everything electrical works.

Could this be a problem to the ignition circuit, or is it just an annoying? thing to live with?

I WOULD APPRECIATE IF SOMEONE ELSE COULD TRY TO STOP THEIR ENGINE WHILE THE HEATER MOTOR IS RUNNING, TO SEE IF THEIR ENGINE RUNS ON FOR A FEW SECONDS, TOO.

By the way, Dave, I've never had any issues with the G valve or brakes in general. And on slippery surface the 1800 feels very safe and stable to brake. I've not yet tried an emergency brake, but will. I always watch the large brake gauge on the wall when I take it to the bi annual Norwegian MOT, which includes rolling brake test. They first do the front brakes, then the rear ones and finally the handbrake. I always get compliments for the brakes being very good for an old car, on any 1800. As long as the rear brakes are correctly adjusted, the 2 hands on the gauge are always dead even between left and right brakes. I can't recall, but I think I've only seen the rear ones lock when they do the hand brake. I'll check next time.

Regards, T

As Chris says, this defies all logic! You have three options:

a) ignore it
b) check every earth point resistance measure to battery negative (neg earth!)
c) disconnect each component (lights wipers radio etc in turn until you find he offending item

Worth checking you don't have any leakage current when the engine, lights etc off apart from clock and alternator (very minor).

Probably caused by a Norwegian Elf I hear they can be troublesome (see workshop manual section L6)

David

Very strange! I don't suppose the Norwegian cars were fitted with an anti-run on device like later US? MGBs?

The electric oil pressure gauge dipping when applying the brakes is typical of a poor connection or just taking too much current for the wire. You may notice similar issues with indicators slowing down when you apply the brakes. It almost sounds as though your heater back EMF from the motor is adding volts through a high resistance connection. Try measuring voltage drops between the battery +ve and both sides of the ignition switch with various switched loads.


regards

David