BMW heater fan final stage unit.

[Dave Plowman (News)]

This unit controls the speed of the heater fans. The same unit is used on several models. It's a sealed SMPS - and pretty small for the current it has to handle. That theory proved by the longest lasting one I've had barely making 3 years. The current one just over a year.

Go to a dealer and the part costs about 70 quid. Buy the OEM version from a specialist 45 or so. A far east copy about 30. The OEM ones look identical to the original and have the maker's name and BMW part number on them. The copies nothing.

I bought this one from a specialist.

I right in expecting it to be an OEM type? It looks exactly like the cheaper copies, with no information on it. The box gives no maker's name or country of origin.

[dom]

=A0 London SW

That ebay supplier has a proper UK street address for his business, and 100% feedback - I would give it the benefit of the doubt.

[fred]

In article , Dave Plowman (News) writes

"BRAND NEW ORIGINAL MANUFACTURERS PART MADE IN GERMANY AND AS SUIPPLIED BY BMW AT £66.00 FOR BMW E36 E46 E39 X5 X3 MODELS WITH AIRCONDITIONING"

Sort of spells it out that it should have BMW plastered all over it.

Are you sure it's an SMPS btw, description of 'resistor' implies it is just the old quick and dirty switchable series resistor that mfrs have been using since ark days for fan control.

[dom]

How many terminals does it have?

[Alan]

In message , "Dave Plowman (News)" wrote

If it's anything like the circuits (control units) on other cars it's probably a thermal fuse that has failed - costing 50p to £1.

In the spirit of this DIY group why not try and open up the failed unit to see what is inside. You may be able to fix it. Example circuit/unit on a Ford Focus

[Dave Plowman (News)]

'Final stage resistor' is just carried over from what was just that on earlier models. These days it's an electronic speed controller. Which also incorporates the on off switching for the fans. My car has the ability to run an electric waterpump and the fans with the key removed to provide heat in the cabin for perhaps 15 minutes with the engine stopped. So it has a feed directly from the battery. In my case it went to full speed and wouldn't switch off. Had to pull the fuse.

[Dave Plowman (News)]

5

[Dave Plowman (News)]

It's cased in epoxy.

electronic speed controller. If I could get inside it I could likely fix the electronics for pennies. But that wouldn't suit car makers these days.

[Dave Plowman (News)]

Not when it's 50% more than an identical one on the same page. If I wanted the copy. I'd have gone for that.

[Mark]

I would buy the pattern part and hope that in the cost cutting to make it, they omitted the epoxy casing so making it a possible repair next time it fails.

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[Dave Plowman (News)]

Sadly not. The only real external difference is the heatsink is fabricated rather than cast.