The complete automotive resource for buyers, sellers, and owners like you.
Car, Truck and SUV Forums at Roadfly
+ Bentley Forums
+ BMW Forums
+ Cadillac Forums
+ Chevrolet Forums
+ Ferrari Forums
+ Jaguar Forums
+ Lamborghini Forums
+ Lotus Forums
+ Mercedes-Benz Forums
+ Maserati Forums
+ MINI Forums
+ Porsche Forums
+ General Discussion
+ Marketplace Forums
Possible Problems: Fan (archive)
[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]
Posted by Grant on December 07, 2000 at 13:45:55:

In Reply to: Aux fan activating at nearly all temp. ranges posted by Ralph on December 06, 2000 at 16:24:28:


Good day. I have an 85 735i. HVAC appears to be working fine at the moment for my heater controls. The problem I am experiencing is that the aux fan or condensor fan will do the following:

Over the spring or summer months, when I hit either the Air Circ button, either of the two A/C buttons or the Defrost button (Defrost button doing this doesn't make any sense to me), the aux fan kicks in at high speed. To deactivate it, I hit either of the up/down or auto buttons separately (no A/C).

Secondly, over the winter months with -4 degrees or colder outside temp., when I hit either of those buttons mentioned above which ACTIVATED the aux fan previously in warmer weather, it doesn't go on, Now this does make sense to me as it shouldn't be required for cooling with this Canadian arctic winter up here.

On one cold day, mind you, it did kick on for some reason (aux fan, that is).

Question: Could I have a malfunctioning temp. switch somewhere that needs replacing or just a good clean?

What I might do in the spring is just disconnect the switches for the aux fan completely and install a separate bypass switch I can activate manually from the interior of the car. Design some sort of James Bond array of switches in a fancy wooden box for the cab of the cruiser, revolving license plate, spray oil all over the road...

Thanks again for your input.

-R.

There are two temperature sensors in the radiator to turn on the aux fan, one for standard speed and one for high speed. Standard speed sensor closes at 190 degrees F and High speed sensor at 210 degrees F. If you have the leads reversed to the sensors then at normal coolant temperature (190 degrees F) the high speed relay would be activated. On a cold day the coolant may never get up to 190 degrees F so the aux fan may never come on.

As I understand it the compressor should come on with the defrost (and the aux fax if coolant is warm enough) so that dry air will blow on the windshield to remove the moisture quicker!

Send me your E-mail address (click on my name above these comments) and I will send you the page from the manual on the wiring for the sensors.


Follow Ups:


[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]
Questions, comments, or problems, please visit the Roadfly help desk.
Roadfly.com Logo © 1997 - 2009 Jump Internet Inc. All rights reserved.