im having trouble figuring out why the radiator fans wont turn on, Even when the ac is turned on it still doesnt turn on, i changed the coolant temp senser. still nothing, i also ran a whire from the battery to the fan and they both turned on. i also sitched around relays and checked fused still nothing. thanks in advance
Do you know how to use a simple electrical test meter? Follow the power until you find where it is not working. Don’t forget the ground as well as the " + "
ok, ill see what i can find
The problem might be the Engine Control Module. The ECM is what supplies the grounds to the fan circuits and the engine coolant temp sensor circuit.
ok ill look in to that i did pull the relay and ran a jumper wire to see if they would kick on and they did witht the ac running i turned it off and they went of exc. i then took the horn relay and sap them so i no the relay is good now.
Here’s how the fan circuits work. Fuse 1, 30 amp supplies voltage to the primary fan relay and to the Mode Control relay. Fuse 2, 15 amp supplies voltage to the auxilary fan relay.
When the coolant temp sensor closes it grounds the ECM. The ECM then grounds the primary side of the primary fan relay which closes the contacts in the relay which turns the primary fan on. When the AC is turned on the ECM grounds the secondary fan relay on the primary side and this closes the contacts in the relay which turns on the secondary fan. The Mode Control relay is also grounded by the ECM and controls when one or both fans should run with the AC on.
would the bcc body control computer have anything to do with it its under the dash on the passenger side
would the bcc body control computer have anything to do with it its under the dash on the passenger side ???
Purely a guess here but I think the ECU controls the fans turning on not the body controller since it should be considered in the engine management group but like I said a guess. You say when the air is on, do you have it on MAX AC? That is the only setting it should kick it on. The only other time the fans would turn on is when the motor temp gets pretty high. Not sure on this specific model but I know the fan sensor on say a 90 Firebird was as high as 246 before the fan turned on.
thanks for the reply i had the car runing while i messed with it i changed some fuses and relays and also unplugged the bcc and the fans run now when the car is hot, now as for the fans and ac i think i tried while the setting was max but not sure the compressor doesnt have freon in it it leaked out i guess so since that not kickin on becouse thats empty maybe thats y the fans dont come on when i turn on air. and when i made the fans come on it with the jumper wire it was the compressor relay not the fan relays. so maybe i just need to get the compressor fixed/replaced to get the fans to kick on that way 2
Sounds somewhat feasible. They are turning on when the motor gets hot so that is a good sign.
yep, its my wife car she used to have a lebaron and it overheated on her and cracked the head on the engine, so had to get this problem fixed asap. thats my i like old school cars like my malibu. is that your car in your pix and is it a cutty, looks good
That’s my 72 Olds, thanks for the comment. I am on the fence about new versus old but I know the old is much easier to work on.
yea, they are and my first project was a 66tbird that was sitting in the back of my wifes grandpa house in the mud we had to tow it out to get it home it had a 428 in it i put on a new carb holldy and electric ignition and new pugs drop the oil and tranny pans cleaned then changed all fluids spark plugs exc… and it right up ran like a champ old school cars were built to last. that car was back there since my wife was little about 21yr ago