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Re: FAQ - Overheating

>
><<<<<	(by Rick Kjeldsen: kjeldsen@domain.elided)
>
>A common problem with later BMWs is that the auxilary (electrical)
>cooling fan doesn't work.  It is supposed to come on at low speed
>when the air conditioner is turned on or when a tempature threshold
>is reached (~190 degrees F).  It is supposed to come on at high
>speed at a higher temp threshold (~200).  A common problem is that
>the low speed resistor burns out, so it never turns on low, then
>when it turns on high, the load of starting at high speed from a
>complete standstill takes out the fuse.  However it isn't unknown for
>the fan itself to be bad.

That's exactly what I had in my 733i. Blown fuses (two of them in parallel,
25Amp each), blown resistor, which I bypassed thinking that high speed is
better. Thanks to Rick, I know better now.

>You can tell if the problem is the resistor or the fan by bypassing
>the thermo switch which turns it on high and checking if the fan turns.
>(details available on request).

On mine, there are two thermo switches, one for 90C and the other for 99C.
Both were bad.

>If the resistor is bad, it is relatively easy to replace.  The resistor
>is .6 ohm (THE E30 ETM IS WRONG, saying it is a 6 ohm resistor!).  It
>is a rectangle about .5"x.5"x2" attached to the fan housing.  You can
>play with standard resistors, but I've only had lasting success using
>dealer parts (about $25). You may have to cut and splice the wires to
>install the new resistor (depending on the model, year and fan
>manufacturer).

If it's US$25 there, it's probably CA$50 here. I'll take the standard, thanks.
(costs $1.00 at local store.)

Does anyone know what the power rating for this .6 Ohm resistor would be,
ie how many Watts?

Again thanks to all who partipated in preparing and sending these FAQ's.
Well done!


- --
Tareef Attar
Toronto, Ontario, Canada