Hello I have a 87 iroc z 305 tpi. And my cooling fans dont come on when the guage shows 230 degrees. I know that the fan on driverside works when the ac is on but neither fan works when ac is off. I was told that it was most likely the coolant temp switch located in tje front of the intake. Is there anything else that I should look for? Any and all help is appreciated. Thank you for your time

 

Also a switch on the passenger side head that should turn on the second fan on high heat. . You can unplug the wire at the sensor in the head, ground that wire, and the fan should come on. I think there are a couple relays near the battery up front, I'd look into them first.

 

I found one relay on core support near the radiator but so far thats the only one. Where is the second one?

 

Also which on of the temp sensors is the one that tells the fan to turn on the one on rightside head or the one in front of intake?

 

I had to rewire mine so that both turn on at 180*. I don't have AC so what I did was take out the toggle switch from under the dash and rewired both fans to turn on with the ECM. I have a diagram somewhere. Lemme me see if I can find them.

 

http://austinthirdgen.org/mkportal/m...ine_wiring.gif

 

The one on the passengerside head. The sensor on the driverside head is the Temp gauge sender (temp gauge on instrument cluster) and the sensor on the intake is for coolant temp which tells the ECM that the coolants temp is 90* or above. If the temp of the coolant is below 90*, the ecm will engage "cold start" system via the 9th injector or by enrichment of the injectors for the later years.

 

Im sorry but the scimatic doesnt show me what im looking for a picture or something like that is what I need .

 

I have a very clean 51000 mile car that I want to make sure is in the best condition

 

The schematic shows you how the the wiring should be. Check your wiring. In most cases, PO's think that rewiring the coolant system is the way to go. My point is make sure the wiring is good to go. If the wiring is good, then sensors is next to troubleshoot. A bit of info: the oem MemCal has a factory setting. Inorder for the secondary fan to turn on is when the coolant reaches 220* - 230* IF The wiring is untouched.

Here are a few reasons why you fan wont turn on;
1. Bad wiring
2. Bad sensor (passengerside head)
3. Bad grounds
4. Bad relay
5. Bad failing MemCal/ECM (which is highly unlikely)

Goodluck man.

 

Also to mention again, the sensor on the intake is not a swittch. It is the sensor that tells the ECM that the coolant is below 90* which engages fuel enrichment for the "cold start-up."

 

Ok thank you. I checked all wiring and the relays and all is in working order. All still factory intact. And the fan workrd today but I think my temp gauge or the sender f9r it isnt working correctly as the guage will go all the way up tto 260 but the motor isnt that hot. Im going to have it on a scan tool tomorrow. Hopefully it will tell me what sensor or whatever is wrong with that.

 

Any time man. Let us know what you find.

 

ok so i had the car on a scan tool. good news the fans and all checked out and everything works as it should. the only thing that isnt working properly is the temp sender for the guage. i will be replacing it today with a new gm sender. and thanks again for all your help.

 

Good stuff man. Good luck.