In article <3976c24c-43c5-4f73-bbc2-1ecdc6606fd9@
25g2000hsx.googlegroups.com>, says...
> Hi
> Heater fan doesn't work, unplugged it, multimeter shows voltage across
> the terminals, on all fan switch speed settings including the ones
> that go through the resistor. Assumed fan was duff, but got another
> one which definitely works, and get the same thing. any advice much
> appreciated, I may be missing the obvious!!!!
Check the condition of the terminals and for voltage in the plug at the
fan end. Also, does it use the body as an earth? Could need the earth
point cleaning up if that's the case.

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sammoseley@gmail.com - 22 May 2008 11:42 GMT
Thanks, the terminals look ok and I get a voltage (about 10V ish) at
the fan end. Not sure where its earthed as the wire disappears
somewhere, but if it was an earth fault wouldn't that mean I wouldn't
get a voltage off it?
not sure if the fan uses a relay, but i've checked every relay in the
passenger fuse compartment and the engine fuse compartment and no joy
i can also rule out the resistor which controls the speed as the
fastest speed should work without it, but it doesn't
Duncan Wood - 22 May 2008 11:46 GMT
> Thanks, the terminals look ok and I get a voltage (about 10V ish) at
> the fan end. Not sure where its earthed as the wire disappears
> somewhere, but if it was an earth fault wouldn't that mean I wouldn't
> get a voltage off it?
It depends on what you attached the other meter probe to.
> not sure if the fan uses a relay, but i've checked every relay in the
> passenger fuse compartment and the engine fuse compartment and no joy
> i can also rule out the resistor which controls the speed as the
> fastest speed should work without it, but it doesn't
sammoseley@gmail.com - 22 May 2008 11:48 GMT
> It depends on what you attached the other meter probe to.
meter probes both stuck into the connector - not anywhere else
Duncan Wood - 22 May 2008 12:56 GMT
>> It depends on what you attached the other meter probe to.
>
> meter probes both stuck into the connector - not anywhere else
You should be able to get 13.8V on full. Plug the fan in & meter from the
back of the connecter & check there is no voltage between Gnd on the fan &
the chassis.
sammoseley@gmail.com - 22 May 2008 13:22 GMT
> You should be able to get 13.8V on full. Plug the fan in & meter from the
> back of the connecter & check there is no voltage between Gnd on the fan &
> the chassis.
Hi
plugged the fan in and meter on the back, get no voltage between
either terminal and the chassis, and also no voltage between the 2
terminals
thanks
Duncan Wood - 22 May 2008 13:27 GMT
>> You should be able to get 13.8V on full. Plug the fan in & meter from
>> the
[quoted text clipped - 7 lines]
> terminals
> thanks
There's a hogh resistance joint between the resistor pack/switch & the
live feed then, check at the back of the switch with it on first, if the
there's 12V there it's the resistor pack, otherwise it's probably at the
fusebox.
sammoseley@gmail.com - 22 May 2008 22:32 GMT
> There's a hogh resistance joint between the resistor pack/switch & the
> live feed then, check at the back of the switch with it on first, if the
> there's 12V there it's the resistor pack, otherwise it's probably at the
> fusebox.
Thanks Duncan, I'll check this tomorrow. So you reckon this reduced
voltage/high resistance is enough to make the fan not come on at all?
Doesn't even twitch when you turn it on.By high-resistance joint I
guess you mean something like dirty contacts?
Duncan Wood - 22 May 2008 23:00 GMT
Or corrosion
>> There's a hogh resistance joint between the resistor pack/switch & the
>> live feed then, check at the back of the switch with it on first, if
[quoted text clipped - 7 lines]
> Doesn't even twitch when you turn it on.By high-resistance joint I
> guess you mean something like dirty contacts?
> Hi
> Heater fan doesn't work, unplugged it, multimeter shows voltage across
[quoted text clipped - 5 lines]
> cheers
> Sam
You'll still see voltage on the resistor terminals when they're dead if
there's no load connected.