Engine overheats when using A/C

[champeny]

1995 325i

When I am in traffic and use my A/C, the car starts to overheat. On the freeway, it is OK, probably due to sufficcient airflow. I am thinking, it may be the electric fan not working. Does anyone know what to look for as far as replacement parts?

Thanks

[Ed Russell]

How many mile are on the car? The origional water pumps in these cars had a plastic impellar. Not sure the spelling on that one. Anyway. They start to break fines off at around 40-50,000 miles. Not really all that hard to replace once the Radiator is out.

Hope this helps

[champeny]

Thanks. I had the radiator and water pump replaced several months ago. I am actually wondering if this may be part of the problem (perhaps they did not hook something up correctly).

[Jared at Pelican Parts]

It may be possible that the sender for the aux. fan may be faulty.

What you might want to try doing is finidng where the connection for the fan switch is. (should be on the side of the radiator) Un plug the connector and use some jumper wire to bridge the two connections, if the aux. fan kicks on, it's the sender, and needs to be replaced...

[champeny]

OK, the aux. fan (the one in front of the radiator) is not turning on. Could this be due to a fault in the "cooling fan dual switch in radiator" as seen in the Bentley manual in fig 18, 610-6 (for those who have it for the e36)? I was hesitent to jumper it, so I have not tried that. I wanted to see if there were other possibilities to check first.
Thanks

[Jared at Pelican Parts]

I looked up the picture. That is indeed the sender. You can jumper it, it wont hurt anything. There should be two speeds for the fan.. High and low. The sender merely acts like a switch.. When the coolant temp raises to a certian point, it allows the electrical current to pass and turn the fan on..

[himes]

Jared,

(1) If you short the in-radiator fan switch, will the fan come on with the engine shut OFF and the key turned OFF?

(2) If there are two speeds for the AUX electric fan, what determines which speed it runs at?

[Jared at Pelican Parts]

Good point. Im not sure if it works independently.

The connections in the switch determine the speed. There should be either three or four.

[champeny]

OK. I jumpered the switch (3-prongs; I guess one ground and the other two are speeds). The fan did not turn on.
I hooked up a volt meter to the switch - 13v coming through.

Any ideas?
I also noticed a separate switch (two-prong harness)that was near by, but not hooked up. I could not find where it should be hooked up to, if at all. I will try to get a couple of pix and post.

[Jared at Pelican Parts]

You need to jumper the connection to the switch... not the switch itself..

[BMWCowboy]

Check your aux fan fuse first>>If it does work when you jump it you can replace the resisitor on the side of the fan