reply: E24 overheating

["Aaron Bohnen" <bohnen@xxxxxxxxxxxxxxxx>]

Hi Piers,

About your query and your overheating 6'er...

> Any ideas? I have noticed that the auxiliary fan in front of the radiator
> only comes on with the air conditioning. Is it supposed to come on when 
> the car is overheating? Sure would make sense if it did. If so where do I 
> find the sensor/relay/whatever?

I have been through this recently myself with my 533i. There are two 
switches that turn on the auxillary cooling fan. They are located at the 
top of the passenger's side of the main radiator. The top one with the 
white body is the low speed switch. The lower one with the red body is the 
high speed switch. You can check them as follows:

low speed, white switch should close at 91 Celsius (196 F)
high speed, red switch should clost at 98 Celsius (210 F)

You can check the operation of the auxillary fan relays by removing the 
leads from the above switches and jumpering them. The fan should run at low 
speed when you jumper the leads to the upper, white switch and at high 
speed when you jumper the leads to the lower, red switch.

The relays are located under rubber boots adjacent to the main fusebox 
between the fusebox and the driver's side fender. The high speed relay has 
two red&green wires leading to terminal 30 of the relay, the low speed 
relay has a single red&green wire leading to terminal 30.

All of this information is available in the Bentley service manual for your 
car - which is the very best $$$ you are likely to ever spend on it. You 
can contact Bentley Publishers directly at www.rb.com or call them at 
1-800-423-4595, or just contact Steve D'G at www.ultimategarage.com - I'm 
sure he'd be happy to sell you a manual.

best of luck with your overheating and with your car!

Aaron
___________________________________________________________
Aaron Bohnen                     email: bohnen@domain.elided
- -Ph.D. Student, Civil Engineering Department, U.B.C.
- -Technicraft Engineering Services

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