I could be, have been, and will be wrong, but it's not for the temp guage is it? I was under the impression that the sensor between 6/8 was the fan, and 1/3 was for the temp guage. Does your temp guage work ok with it disconnected? If it works o-tay, then I'm wrong again...

Later,

Carl :crazy:

 

Hi Scorp:

On a Z51. the (at least on my 86 & I think yours would be the same) that switch is for the auxillary fan. If you remove the wire with the key in the run position and ground the wire, the Fan should start running. If it does not come on. run a hot wire directly to the motor amd make sure the ground wire is good - the fan motor should run. If the fan motor runs, then check the aux fan relay (top left side of the fradiator shroud) for power. open or shorted wires and so on. I suggest a MAD switch for this application as it will turn the aux fan on a little sooner.

Ray

 

The device between 6&8 is the temperature sender for the dash temp gauge.

 

Ding Ding Ding...we have a winner!

Thanks -=Jeff=-. I did it and my aux fan did come on. So no I know that it does work. But what is the temp that the aux fan is supposed to come on at?

Without my AC on my main fan comes on at 228 degrees. My main fan runs at all times with the AC on.

Does the aux fan kick on at 238-240 as stated above? If that's the case then mine will likely never come on as my main fan does a great job of dropping the temps once it comes on at 228 degrees.

Thanks again.

 

I'll chime in... just to make things more confusing I've had a toddy or 2 but believe this info to be fairly accurate.

First, the earlier C4's (84, 85, 86(?), 87(?)) had the temperature SENSOR on the driver's side head between cylinders 1 and 3. This is a SENSOR or thermister that supplies an analog "signal" to your ECM and dash display... not to be confused with the temperature SWITCH on the passanger side of the car. Don't forget... your ECM controls the MAIN fan... NOT the aux fan or both.

Second, these same earlier C4's had a temperature SWITCH on the passanger side head between cylinders 6 and 8. Now, my Mitchell's schematic appears to show (see pic below) that if you have a single main fan that this SWITCH is in the same control circuit for the ECM... maybe a "fail safe"(?). If you have the V08 RPO, amongst other items, there will be a second or aux fan and the schemtaic shows an extension of the entire circuit. Anyway for the aux fan owners, this is a SWITCH that supplies a "signal" for the control side of the aux fan relay located on the firewall behind the battery and directly below the cruise control vacuum diaphram. This location is for the earlier years. This SWITCH is a nomally open switch. It takes a certain temperature, say 230F or so - not sure exact temp, to close and ground the circuit (grounds on the block) through the coil side of the relay. Once the circuit is closed the coil side of the relay is energized which in turn energizes the high current or contact side of the relay... turning on the aux fan. Well, it does in my car. If I turn the key on but not start the car and ground the switch connector to the block the aux fan will come on... not the main fan. I think there are 2 conditions for the aux fan to be energized. 1) When the A/C is on the Aux fan comes on... and stays on until A/C is turned off. 2) The coolant temp reaches 230 or so and turns the fan on through the switch. Now, I have the MAD SWITCH installed... turns the aux fan on at 200F and off at 185F. Again, this assuming the A/C is NOT on.

Perhaps a change or swap of the sensor/switch locations was made in later years but this info is at least accurate through early 86.

 

:D It's a secret.....

 

I wish I Knew waht my connector looks like because mine is disengrated too. Mine keeps falling off, not like it does anything with the stock temp switch. Whenever I replace the connector, I am going to buy a 200 degree switch so my aux fan is usable.

 

Why dont we just try this. I have a 90 so I am different then the years stated.
Correct me if I am wrong, I have a 90 anyhow...
If you unplug the PASSENGER side wire from the sensor (6&8), the only thing not working would be the dash temp read out right?

So that would leave the Dirvers side (1&3) sensor to control the AUX fan correct?
======================================== ======================================== =====

For the guy whos AUX fan is not working. you need to test to see if your fan motor is even good. will it turn if you feed it 12v?

 

I would never even know if mine AUX fan worked, My car has barely been over 200 degree in the last 7 years (Aftermarket chip)

 

Both of your statements are correct for my '89 as well.

 

quote:

________________________________________ ________________________________________ ____________
I have a 90 ...
If you unplug the PASSENGER side wire from the sensor (6&8), the only thing not working
would be the dash temp read out right?

So that would leave the Dirvers side (1&3) sensor to control the AUX fan correct?
________________________________________ ________________________________________ ______________

======================================== ======================================== =====
Both of your statements are correct for my '89 as well.
======================================== ======================================== =====


Just so I dont confuse anyone, the 90 and probably 91's dont have a sensor on the driver side head for the AUX fan.