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vr6paul

Heater motor thermal fuse trouble shooting

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Thanks to the various threads on this topic I have got my hands on the replacement thermal fuses from maplins.

I have now had a few goes at soldering the fuse in but with no success re speeds 1,2,3 on the fan. Speed 4 still works. On testing the new fuse it still seems ok (zero resistance)so I don't think I've fried it. Could there be an additional issue causing the fan speed problems?

I don't think it is the connection at the dial either.

Any ideas or tips?

Many thanks

Ps while removing the motor I discovered a soaking wet floor well - lovely - new plastic lining needed in the passenger door then!

The jobs never end!

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Just a thought ......... it could be that when you are soldering the fuse into place that the heat generated by the soldering process is actually blowing the fuse as it is a thermal one.

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That was a worry but when I test the fuse I am getting next to zero resistance so I'm assuming they are still good?? The old fuse shows massive resistance. Could the resistor pack be gubbed or should I try the fuse approach again?? Cheers again!

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http://the-corrado.net/showthread.php?t=47180

 

Have a look at that.

 

Also, check continuity in the feed across all resistors, i.e. one lead from your multimeter meter on the spade input to the resistors and the other on the spade output on each. You will see the highest resistance, but still with continuity for speed 1, less for speed two three and four. If any of them are open circuit you know where your problem is.

I had a slightly different resistor pack (because of aircon) and my issue was between the two faces under one of the rivets! It was ever so slightly loose and would therefore throw an open circuit randomly. Let us know how you get on - all the best.

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Ok im at it again!

When testing resistance between the female bullet terminals on the outer casing of the resistor I get very low resistance across them all except the one labeled num1. I get the same result when testing between the spade connector on the opposite side (the one connected to the thermal fuse).

Does this mean another problem somewhere??

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Guys thanks for all your help.

After giving up on my soldering marathon I went back to the switch/dial. Got all the copper connections out and cleaned them. I had previously adjusted the copper tab that is attached to the knob/dial but I did not know at that point that it had to contact front and back (2 copper rings effectively). I think in initially adjusting this tab (before replacing thermal fuse) I had inadvertently moved the tab away from the "far away" or bottom set of connectors.

I then fixed the thermal fuse and kept refitting the motor with no joy - now that I have adjusted the copper tab properly (more of a twist in it now so it is effectively wider) it all works! Yee ha!

 

Another job done thanks for all the help,

Another job added though as I noticed a huge crack in the windscreen today - auto glass booked for Friday.

Tomorrow it's door membrane and an abs sensor.

Fun fun.

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