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Heater motor wires

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Ever since I got my 620 there's been two wires hanging below the dash. One has another wire spliced into it and the hook th the fan switch thing. One my high speed has been working so I figure the other 2 speeds must be those wires. I found where they go but the problem is which goes where? There's to connection points on the motor... Help?

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Power goes to and through the motor and from there through the switch to ground. To get a slower speed it may pass through a resistance and then to ground. The 'resistance' is a small coil of wire mounted inside the blower case (to keep it cool) above the gas peddle on the 620.

 

The low speed resistance coil looks like this and plugs on top the blower part of the heater assy. on the driver's side. Probably blue wires going to it?

 

electrical620heatertwospeedcoil.jpg

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That looks like the right part. My wires are yellow and one seems to splice to a black wire that seems to be a ground. Just curious if it matters which wire goes where

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The coil in the picture will work the same if wired backwards.

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does anyone know the resistance rating of the coil?

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Not off hand but its the wattage rating that is important. It's going to get very hot. That's why it's mounted in the air stream from the fan, to cool it.

 

You would need to know the current drawn my the motor. Certainly it's less than the fuse used to power it. Say 6 amps (just a guess)

 

Using Ohm's Law we can work out the motor resistance by R = V/I or resistance = voltage (12) over I (current 6 amps) so the resistance would be 2 ohms. So if we add another 2 ohms of resistance in line with the motor resistance (2 ohms for a total of 4 ohms) the motor will flow half the current and theoretically run at half speed. Now power in watts, is V x I or Voltage (12) x I (current 3amps) or 36 watts. Your resistor must be able to handle 36 watts.

 

This is just a guess that the motor draws 6 amps. It may only draw 3 or maybe 8... I don't know.

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:) perfect 

 

I'll just test the motors amperage at full voltage & work backwards from there

 

THANKS.!!! 

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Just had another idea...

I'm wondering if I could cut in half (or thirds) one of those barrel wire connectors for connecting two pieces of wire together. I'd have to find one with a large enough id to slide over both the broken ends. Then if the coil material is too hard or brittle, maybe I could solder the ends to the connector?

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Mine fell off/broke off one end. I just hooked it back up and got the low setting for the blower back

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It gets too hot for solder, I think and why it's inside where the air blows over it to keep it cool.

 

Get a small diameter piece of metal tubing, smaller the better, about 1/4" long. Shove both ends in and crush with vice grips or crimping tool.

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IIRC the coil heats up and acts as a heat source until the water warms up from the radiator.

 

My 86 M1008 (Chevy pick up) has a similar coil it does dual duty, one reducing the fan blower speed and two pre heating the air from the heater core.

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IIRC the coil heats up and acts as a heat source until the water warms up from the radiator.

 

My 86 M1008 (Chevy pick up) has a similar coil it does dual duty, one reducing the fan blower speed and two pre heating the air from the heater core.

 

:lol: So why doesn' t high speed have this too?

 

Or if it works, it only works as fast as the water heating up. :lol:

 

 

Next time it's cold, start up your heater like normal without the engine running and see how warm the air (doesn't) get.

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This isn't even wired correctly.
The piece the coil is connected to has a certain purpose and that is not it.
Who knows?
electrical620heatertwospeedcoil.jpg

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I had a 620 but I don't remember if this was my picture or not. The 1200 has one similar.

 

I guess if the wire broke off you could re attach it with a nut and bolt.

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