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Smith's Heater Wiring Question

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77blueblunder

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I spent today removing and refurbishing the Smith's heater on my 77B. Here is my question. There is a resistor of some sort inside of the box. I believe my heater is of the two speed type but the DPO had cut the wires. I soldered two wires to the terminals on each end of the resistor and ran them outside of the heater box. Now I have the two wires that plug into the heater fan and the two wires from the resistor. I am not sure what to do next as I only have three plug-in connectors in the wiring harness for a total of four wires. I looked at the wiring diagram but I am stumped? Sound familiar to anyone?

Thanks
 
Familiar yes! My MG manuals are on loan to a good friend, but I have some older diagrahms of LBCs that will help. I need the color of wires at the plugs and the color of the wires in the resistor. Let me know the number of wires at each plug and the colors. All British cars use mainly the same colors.
 
Larry - Thanks for your response!

I have a green/yellow a green/brown and a black on the harness.

Then there are places for two wires to plug into the heater fan, and of course the two wires I soldered to the "resistor" (or whatever it is)inside the heater box.
 
I printed these and laminated them. Very handy in the shop and easy to read. Now If I can only figure out my reverse lights /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
Reverse lights, himmm, my maglight really works well.
 
I'm sure you are only using a "Lucas" Mag light, right Jack!
happy0148.gif
 
I looked at the advance autowire diagrams first and the closest one is a 1978 but it does not show the resistor. Guess I'll just have to wing it!!
 
Green Brown and Green Yellow and black. Black is ground ( naturally) Green is switch power, Bn and Y are probabaly to resistor. Check you switch on dash and it may look like this. GB / GY / Gr resistor may be gy/gy or gb/gb. 2 speed motor would be G and G. Or motor can be W (white ) GY and Br.

Check you switch. Switch goes thru resistor for low speed then to motor. Postition of switch will tell you which color is high or low. Middle is usually power to switch.

Should have never loaned out my manuals.
 
Jarhead, The resistors can go bad, but they are usually pretty protected and last a long time. Unless mice or water gets in and sets they are usually OK. The only way to know what resistance needed would be to measure a good one and match it.
 
Mine had a coil leak and it could have gotten wet. Does anyone have a new one they could measure and let me know how many ohms it should be? If I had a new one I would just install it without measuring it but don't want to replace a good one.
 
One way is to measure the resistance across the motor and add a resistor that is 1/2 of the resistance of the motor (this would make the motor run at about 1/2 normal speed) or get one that is about 1/4 of the motor resistance and then the motor would run at about 3/4 speed.
Bill
 
Thanks Bill, I ran a check on the motor and the resistor is right about 3/8 the resistance. I think it is okay.
Ed
 
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