chevydrvr

iTrader: (1)

What is the sensor or switch that controls the fan? My car keeps overheating when it runs for more than maybe 20 minutes. The temp gauge hits the red.

I've been told by my uncle that it is the coolant temp sensor that turns the fan on and off. I search that on autozone, and also found a fan switch. What exactly do I need to make the fan turn on, and where is it located on the car?

As of now, the only way to turn the fan on is to turn the AC on.

Thanks!

Apeiron

The primary fan is controlled by the ECM, the secondary by the fan switch.

chevydrvr

iTrader: (1)

But I only have one fan?

eseibel67

If you have TBI, there is only 1 fan. It is controlled by the fan switch only, not the computer.

chevydrvr

iTrader: (1)

Okay, What is the switch called? I think I need a new one?

camaronewbie

http://www.autozone.com/autozone/par.../N-iteceZ9pd8z

If that works. It's called a fan switch (AZ calls it a Radiator Fan Switch), it's located pass side head between #6 and #8 spark plug. In the head, NOT the block (there is also a very very similar looking sensor in the block same side, it's the knock sensor).

henryd3

iTrader: (128)

Yeah, if the fan works when you turn on the AC that means your fan and relay are good and you just need to replace or properly connect the fan switch described by Newbie above. You may want to chjeck your wiring first. Grounding the wire to the switch with the key on should turn on the fan. There are alternatives to the stock temp switch, some of these are discussed in this thread
https://www.thirdgen.org/forums/cool...ernatives.html

chevydrvr

iTrader: (1)

When I get the chance, I'll check the wiring, but how do I check it with ground like you said?

camaronewbie

Just touch the wire that goes to the fan switch to any bare metal on the car - with key on the fan should run - that lets you know the wiring is good, and probably just the switch is bad.

chevydrvr

iTrader: (1)

Okay, thanks! Ill try that. If the wiring is good, then I just need what he linked to above?

chevydrvr

iTrader: (1)

Will the fan switch from autozone (part number sw500) work on my 92 rs 305?

http://www.autozone.com/autozone/par...artNumber=true


And I know this is off topic, but will this idler arm work too?
http://www.autozone.com/autozone/par...artNumber=true

They both say they fit my car, but I don't really like to trust that. Thanks!

chevydrvr

iTrader: (1)

I knew that part, but I just wanted to know what specifically tells the ECM to turn the fan on. I've now learned that the fan is controlled by a relay which is either controlled by the AC or the ECM. I also learned that either the switch is bad or the relay. The relay is good because the fan comes on when I turn on the ac.

I ordered the switch from autozone above. Please let me know if it'll work. And, just on a side note (so I don't have to start a complete new thread for one quick answer) will the idler arm work?

Thanks!

henryd3

iTrader: (128)

The ECM has nothing whatsoever to do with the fan. Either the fan switch or the AC on switch grounds the relay which sends power to the fan. Period

chevydrvr

iTrader: (1)

Alright. I got it. Now will that switch I ordered work? That's all I'm asking for!

henryd3

iTrader: (128)

Should be just fine. Make sure the wiring to it is kept away from the exhaust manifold so it stays intact and melt free

chevydrvr

iTrader: (1)

Thanks!

chevydrvr

iTrader: (1)

One more question... Will I have to drain any fluid before removing and replacing the fan switch?

henryd3

iTrader: (128)

Coolant will come out. You can drain the whole engine and later refill or just try and do it quickly to minimize the loss. Depends on whether some spillage will bother you or not

chevydrvr

iTrader: (1)

Can I possibly hurt anything if a little spills out? I plan on using a rag to quickly block it and then put the new switch in.

henryd3

iTrader: (128)

Don't drink it and you'll be fine

chevydrvr

iTrader: (1)

Thanks so much for the help!