Aux Fan Not Working

[lgilbert50]

My aux fan on my 84 is not working. Checked the wiring diagram in the factory manual and it does not show the wiring. Just wondering when does the fan come on and what triggers it so I can trouble shoot it.
The fan works when I apply voltage to it.
Any help will be appreciated.
Thanks
Lowell 84/Z51

 

[94conv.]

could be a relay, on the 89's they are on the drivers inside fender, a green wire I do believe, Im sure someone else on here will know for sure but you may check for it

 

[JonM]

What happens when you put the AC on? Does the fan come on?

 

[lgilbert50]

AUx Fan

Air hasn't work since purchasing car. Have the compressor but need to find time to flush and replace compressor. I've been thinking the same that it only comes on with the air, but I would like to get confirmation
Thanks
]

 

[8388]

Coolent sending unit located on drivers side head is what sends the signal on 86 thru 91 models. Not absolutely sure about 84. It's not supposed to turn on till coolent temp reaches 225 degrees. There's an aftermarket sending unit available that kicks it on at 182 degrees.

 

[lgilbert50]

Replaced temp sensor because of an other problem and my main fan works as it should.
Thanks
Lowell

 

[JonM]

Lowell ...let me just throw this web site at you...we Crossfire guys have to stick togther.

http://www.crossfire.homeip.net:81/cftest/default.asp

 

[lgilbert50]

Thanks already did.
Log live Crossfire!

 

[lgilbert50]

Thanks already did.
Long live Crossfire!

 

[94conv.]

arent there two temp sensors? one on the passenger side of the engine and one on the drivers side ?

 

[lgilbert50]

Good question, have to check tonight.
Thanks

 

[wishuwerehere82]

There are two temp. sensors. The coolant temp sensor is on the front of the intake manifold. The block sensor is on the driver's side with a green wire going to it. The one on the passenger side is the knock sensor.

 

[lgilbert50]

Found Ken's coolant fan troubleshooting post but wonder if this would apply to an 84. It's my understanding that the 84 fans are controlled differently the later years.
Thanks
Lowell

 

[8388]

I called it coolent sensor because it works off coolent temp. The single green wire sensor on the driver side head is the one that operates the aux fan.

 

[thirdtimevetteowner]

8388, where would I find the aftermarket 182 degree sending unit you mentioned above? Have scoured Jegs and Summit w/no luck.

 

[JonM]

8388, where would I find the aftermarket 182 degree sending unit you mentioned above? Have scoured Jegs and Summit w/no luck.

http://www.madvet.com/shop?frame=3.138.944

 

[WhalePirot]

Not true, guys

The '84 only had ONE fan and it is switched by the sensor on the passenger-side head. The other temperature sensor (driver side) feeds the ECM, which does not control the fan. This was changed in mid '85. The single fan is reported to be just fine to cool HUGE engines. I know it cools my 406 quite well; fan still switched the stock way.

If you have an aux fan, it's anyone's guess what triggers it. Some prior owner may have installed an aftermarket fan with its own sensor/trigger, or did a modified (or not) stock system, from a later Vette.

 

[RonJ]

On my 85, the sensor in the right side head provides a ground to turn the auxillary fan on at high temp.

To check the fan, take the wire off the sensor and ground it. The auxillary fan should come on.

Ron ...

 

[stratman]

One Sensor and One switch

The L98 C4 that has the HD Cooling package uses one (1) sensor that sends the temp to the ECM which controls the main fan. The engine also has a temp switch that turns on the AUX. Fan. It does not go through the ECM. If you need the schematic I can scan it and send it. Failure is a common problem. You need to check the fuse link wire for the main power supply to the motor. (NO FUSE) but fuse link wire. 0.5 MM2 wire It also could be the relay or switch.

If your car also has the C68 electronic A/C hopefully it did not go bad. It costs about $260 for the unit.

 

[geekinavette]

Boy there's a lot of confusing info in this thread!

The '84 is in a world all its own when it comes to the cooling fan setup. It comes from the factory with only ONE (electric) cooling fan. The ECM is NOT involved in any way shape or form with the operation of the cooling fan.

There are THREE coolant temperature sensors on the '84...

1- Driver's side cylinder head: feeds the coolant temp gauge in the instrument cluster

2- Pass. side cylinder head: controls the cooling fan (this "switch" is connected in parallel with the AC fan switch)

3- Front pass. side of intake: sends coolant temp info to the ECM


Diagram for the temp gauge sensor in the drivers' side head (bottom left of the diagram):

Diagram of the fan, relay and temp switch in the pass. side head:

Diagram of the ECM Coolant Temp Sensor (CTS) in the front of the intake (bottom left of diagram):

Bill