Heater blower woes

[Oldiebut goodie]

Old Webastos used hefty great resistors and they had to be mounted on metal to act as a heatsink - I am surprised that these ones aren't mounted the same.

[Hacksawbob]

Ive ordered a 15 amp pwm motor controller for £8 and plan to run it all through the full speed wire. The potentiometer is a little weedy looking but I'll let you know how I get on. got to be better than those bulky old resistors. Mine was working on full speed but not the other two, then the switch froze up. probably more a corrosion issue/switch issue than the resistors but isolating them out of the equation has got to be better than ripping the dash out right? plus full vaiable fan speed (in theory!)

[123-jn]

well its all back together and its all working thank goodness. It is a bit of a faf to do the job but now I have a blower again with all three speeds. I cleaned up both the earth crowns while the dash was off and all the spade connectors but still seem to have a voltage drop between the battery and the fuse box of about 0.5V. I can only think that VW use cable that degrades. I remember on my old 1963 beetle that there was never enough power to throw the relay on the starter (6Volt) and eventually I replaced the wiring from the ignition switch to the solenoid and hey presto no more trouble. I will try to upload the pics soon but my camera is playing silly whatsits at present. I need to find a card reader.

[CovKid]

All heavy current-carrying cable tends to degrade after 30 years of abuse. I replaced all the alternator/battery/starter cables this year (see WIKI) and also ran a new heavier guage one from battery to front, and the fusebox then taps into that.

The other issue is that anything that goes bad, like a blower motor which can draw excessive amps on startup as it ages, also heats up the main power feed. Incorrectly rated fuses compound problems. In adverse conditions where almost everything gets switched on, the load (potentially) can be enormous at times. You can see how fires start to be honest.

[Hacksawbob]

Just follow up, I tried the resistor switch listed above, it worked well... For a week, it got extremely hot and would need to be installed with a cooling fan which might have made it last longer. There is a 30amp version which may be better suited.

[CovKid]

I would think only a reostat would cope with it long term and simpler possibly. Be interesting to see though.

[Hacksawbob]

That said I have a two way switch which will do for now with mid and high sttings, but it doesn't fit the hole in the facia I think the switch contacts are a bit weedy in the original switch, has anyone found a replacement that has better contacts in it?

[WLC]

I can only think that VW use cable that degrades.
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It's not just VW
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