fan not coming on

[carpe_noctem]

ok i'm repairing my friends 90 cavalier 4cyl auto.

the fan will not come on. so it's overheating.

the a/c clutch will not engauge when she turned it on. so no A/c.

these are why she brought it to me. now the engine wiring was a jerry rigged disaster so i replaced it all with a better harness that i checked out before i installed everything in the harness is fine and now installed. it's easier to work with decent wiring so your not fighting 2 problems.

there is also a brand new coolant temp sensor.

and jumping the relay will turn on the fan


and still the fan will not come on if i leave the car running in the garage, and the a/c isn't working. whats going on with this car????????

[kirkwood158]

if you are jumping relay and the fan comes on the relay would be bad is my thought. Replace relay right. If you have already replaced coolant temp sensor which is part of signal to ECM then to relay. the new one does not work or the ECM is not signaling relay. but you should check all parts again I have seen new parts bad right out of box. A 90 cavalier?????? for the 90 model I am not completly sure of fan run sequence. I do not have schematics for that year. need book

[Helmuth48]

You sound like a pretty electircal smart person. So that this point, As Kirkwood noted, I would get a wire schematic for the car. This will save you a lot to time and guessing.

Double check the sensor, fuses, relays and connections again.
Remember the ECU is the brains...everything feeds to it and tells what to do...and when.

I will dig throught my book.s...under the beer cans, and see what I can find.

Cheers Mate :}

JzJzz .....and the Man from Down Under