Author Topic: Temp guage/Aux fan issue (Read 3583 times)

beemer1 · « **on:** March 28, 2009, 10:21:00 AM »

I've been lazy about finding out why my aux fan doesn't turn on anymore when the temp gets hot (it works when the ac is on). The problem is when I come to a red light/stop the temp needle goes just above half way sometimes inbetween 1/2 and 3/4.

Which sensor is responsible to turn on the aux fan when temps get hot?

Steve

doitover · « **Reply #1 on:** March 28, 2009, 01:25:58 PM »

There is a temperature switch on the right side of the radiator.

Quote from: beemer1;69068

I've been lazy about finding out why my aux fan doesn't turn on anymore when the temp gets hot (it works when the ac is on). The problem is when I come to a red light/stop the temp needle goes just above half way sometimes inbetween 1/2 and 3/4.

Which sensor is responsible to turn on the aux fan when temps get hot?

Steve

beemer1 · « **Reply #2 on:** March 31, 2009, 07:18:42 AM »

Is that the only sensor/component that would cause the aux fan not to turn on?

I'm gonna check it this weekend, thanks!

Steve

monty23psk · « **Reply #3 on:** March 31, 2009, 09:51:56 AM »

No, there can be other ones. I would recommend starting from the fan to troubleshoot. You say that it works with AC, that is good. The AC turns the fan on the low speed. I would just the radiator switch with a alligator clip wire or regular wire to see if the fan comes on at low and high. If it does, then the radiator switch is bad. You can test the switch is boiling water and checking for continuity but depending on age of car, would be easier just to install switch. I can help with other sections as I have gone compeletly thru all the scehmatics of this system.

doitover · « **Reply #4 on:** March 31, 2009, 09:53:38 AM »

No, there is also a high temp relay and fuse.

Quote from: beemer1;69197

Is that the only sensor/component that would cause the aux fan not to turn on?

I'm gonna check it this weekend, thanks!

Steve

beemer1 · « **Reply #5 on:** April 01, 2009, 12:34:59 PM »

The fuses in the fuse box look fine. I'm just gonna start by testing the radiator temp sensor and go from there.

Does the relay also power the aux fan when the a/c gets turned on?

Thanks a million guys!

Steve

doitover · « **Reply #6 on:** April 01, 2009, 01:28:39 PM »

There are two relays, one for high and one for low. The AC turns on the low speed fan.

Assuming you have a 91 318 Fuse 20 supplies power to fuse 19 which supplies power to the temp switch. If you have the ignition on
and jump pin 1 of the temp switch to pin 3 the fan should come on.

If it doesn't then check to see if there is power on pin 1 of the switch.

If there is then jump Relay K6 pin 30 to 87. The fan should come on.
If it does it is either the temp switch or the relay. If it doesn't and the
fuse is good, then it's something in the wire between Fuse 18 and the fan.

Quote from: beemer1;69239

The fuses in the fuse box look fine. I'm just gonna start by testing the radiator temp sensor and go from there.

Does the relay also power the aux fan when the a/c gets turned on?

Thanks a million guys!

Steve