Cabriolet rear screen blower

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M3KUK
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Post Mon Oct 01, 2018 11:14 am

Hi trying to get this working on my K reg cabriolet. I have just bought a spare motor and connected it up to a 12v power supply. The motor works fine but the heating element won’t get hot. I measured it’s resistance and it’s 800 ohms. This seems a bit high? Anyone know what the correct value should be?
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paultv
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Post Mon Oct 01, 2018 5:09 pm

well its fed by fuse 8 which is 30 amps - so maximum dissipation could be 360 watts - this would result in a resistance for the heating coil of 0.4 ohms.

In reality I expect the heater in the blower pulls no more than 10 amps - resulting in about 1.2 ohms for the coils...

in any event the 800 ohms you have would produce about 15 milliwatts of heat with 12volts going through it - enough to warm a flea - so I'd say its stuffed.

Paul :-)
4th May 1990 325i Convertible.

BMW E30 Cabriolet Best Mod Ever:

https://bmwe30cabriolet-wdm.blogspot.com/
HartgeH27
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Post Mon Oct 01, 2018 5:22 pm

I have a couple of spares if you are interested.

Iain

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M3KUK
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Post Mon Oct 01, 2018 7:41 pm

eBay strikes again! Sold as a good working unit!
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Satan
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Post Mon Oct 01, 2018 8:47 pm

Even when working they struggle......
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M3KUK
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Post Wed Oct 03, 2018 9:04 pm

PM sent Iain.