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1999 Mercedes C43, 2003 SL 500, 2000 BMW 540/6 , !981 Alfa Spider
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Discussion Starter · #1 ·
Automotive tire Audio equipment Electrical wiring Gadget Cable
Electrical wiring Audio equipment Cable Eyelash Technology

This is an evolution of a previous post. Long story short, I'm in the process refurbishing the heater box in my 81 Spider with A/C. I've finally got the heater motor out after ages of toil. My issue is that I purchased a replacement blower motor years ago and now that I'm nearing the time to install it I have some concerns. To my non-electrician eyes the "new" motor seems to have small and maybe inadequate gauge wiring. If anyone has used this model of motor OR if I'm being a being a bit paranoid, I'd love to hear your opinions. I've never had any issues with this vendor, but just want to be cautious because I don't want to ever replace another blower motor. Ever.
 

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1999 Mercedes C43, 2003 SL 500, 2000 BMW 540/6 , !981 Alfa Spider
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Discussion Starter · #3 ·
Don't think I got any info on the current draw. I called to ask about the wiring, but the person I spoke with suggested I have the motor re-wired if I was concerned. Maybe I'll try to contact someone else...
 

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But Mad North-Northwest
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When I measured my aftermarket blower (not the one you have) it pulled about 7A on high.

From the tables I'm seeing even 18ga should be fine for such a short run. I think you'll be fine.
 

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'66 Sprint GT, '67 Duetto, '70 BMW 2800CS
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I think you'll be fine.
Agreed. The original motor may have just used wire that had thicker insulation over the same gauge copper. Or it might have had larger gauge wire than necessary. There are some poor-quality replacement parts out there, but I doubt any manufacturer would make so bone-headed an error as using a wire gauge that couldn't handle the current load.
 

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1999 Mercedes C43, 2003 SL 500, 2000 BMW 540/6 , !981 Alfa Spider
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Discussion Starter · #6 ·
Agreed. The original motor may have just used wire that had thicker insulation over the same gauge copper. Or it might have had larger gauge wire than necessary. There are some poor-quality replacement parts out there, but I doubt any manufacturer would make so bone-headed an error as using a wire gauge that couldn't handle the current load.
Ha! Fair points, but you're definitely more trusting than I am!! I think if Centerline was still offering these for my application I might feel a little better. Looks like the ones offered now look like my original motor.
 

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'66 Sprint GT, '67 Duetto, '70 BMW 2800CS
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keep the old motor, that looks quite restorable!.
As an aside, the old motor looks like it is constructed in a way that would allow you to easily solder larger gauge leads on to it if you wanted. Changing the leads on the new motor looks tougher (again, not that I think you need to).

If you're nervous about the new motor, why not hook it up to a battery on the bench, and let it run for 10 min or so. If the wires melt, then your fears were well-placed. Better to find out before you spend the time installing it!
 

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But Mad North-Northwest
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keep the old motor, that looks quite restorable!.....and the low speed resistor looks shiny and newish (normally they are rusted to bits)
That's a good point: the original doesn't look bad at all. I might be tempted to just clean and lubricate the lower bearing, bench test, and then reinstall. Especially given the hit-or-miss quality of some of the newer replacement parts.

If you drill a small 1/8" hole in the low point of the heater box, that'll let any water that gets in drain and help prevent rust like that from happening.
 

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Discussion Starter · #11 ·
Tom--Right now the issue with the old motor is it only works at high speed. I'm assuming there's a problem with the resistor. Otherwise it runs very smoothly and quiet. Looking for a shop locally that could possibly refurbish. And... The first thing I did when the lower housing came off was to drill that hole.

Brian--I was a little shocked at the suggestion that I get a "new" motor rewired. I'm sure he was trying to be helpful, but it wasn't reassuring.
 

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But Mad North-Northwest
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If you have a DVM it's pretty easy to check if it's the resistor or the wiring to the resistor. Either one should be pretty easy to fix if you know how to solder (or are willing to learn...it's not very hard).
 
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