I’m having an issue with my electric fan. If I turn the AC on the fan will come on but it won’t engage when it comes to temp.

I have new thermostat
new sender (although I thinks this only does the gauge)

thoughts from the group?

 

Application? A single fan tbi or v6 ? Have you grounded the temp switch ?

 

Sorry V8 TBI

 

what happens when you ground the cylinder head temp switch located on the passenger cylinder head ?

 

Actually, ground the wire that goes to the switch, not the switch itself. Those pesky details.

 

yes I should of elaborated on that, thanks

 

Sorry for the delay, pesky work had me tied up.

Which of the wires is ground?

 

The engine block is ground

 

The wire going to the fan sensor in the block is blue...

Do I ground that wire blue? Does that complete the circuit for the fan to turn on?

 

Should be wired like this, this shows a green/white to cylinder head temp switch. Could ground at the relay to test the relay. The knock sensor lead could of been swapped if it’s a blue wire.

https://austinthirdgen.org/storage/d...an_V8_vinE.jpg

 

https://austinthirdgen.org/storage/d...rk_control.jpg

you never said your year but this shows ks as blue

 

Sorry, this is a 1991 RS V8 305

 

This is for spark control, I'm not seeing the connection

 

just saying the ks and temp switch could be swapped

 

Yup, sounds like you have some connectors plugged onto the wrong things.

The fan switch wire is dk grn w/ wht stripe. Blue is probably the knock sensor. They are the same connector type and are physically close together, therefore easily plug onto the wrong device.

 

The stock GM fan switch does not enable the fans until around 220F.

 

I fixed the issue with the wires (green/white is now on the correct sensor) and replaced the fan sensor and the fan still doesn't engage unless the A/C is turned on. I've let the temp get up to 240 before shutting it down. Any other suggestions?

thanks for your help

 

sensor as in coolant temperature? Or cylinder head temp switch ?

 

Head unit

 

This is what I used to fix that problem, from Hawk's. Even the OEM replacement switches have been known not to turn on until over 240 in some instances. Before I installed this I had just grounded the green/white lead. I figured it was better for the fan to run all the time than wait until it over heated to kick on.

 

Chances are the switch is coming on at the right temp but the temp gauge is showing the wrong value. If you want a lower one get a 1989 turbo trans am switch 210 on 195 off.

 

wells sw555 can remove the old temp sw put in in some water on the stove with a vom hooked up and thermometer in the water see if you can get it to close. You would see continuity from center to body.