Coolins fan dosent turn on when car reaches operating temp but will turn on when a/c compressor engages any idea??

To check the fan clutch, drive the vehicle until it reaches operating temperature. stop, turn off vehicle, remove the keys from the ignition. open the hood and reach dowwn to the cooling fan and try to rotate it. if it is spining freely or with very little effort at operating temp then the clutch is bad. if it will not rotate or takes a significant effort it is good.The clutch spins freely at cold start to help the engine get up to operating temperature more quickly by allowing the fan to freewheel. as the temp rises the clutch engages allowing the fan to spin a at RPM allowing the fan to draw in cool air through the radiator. I hope this helps.....

The air con fan comes on when the air con is engaged, the engine fan comes on only when the engine reaches operation temp. controlled by a temp. switch. on the block or radiator .

If the fan runs when the ac is on, you can assume the fan motor and relay are ok. The temp sensor signals the computer when the engine reaches 220 degrees and the computer grounds the fan relay to power the fan.
You would need to check the operation of the temp sensor and verify the engine temp, usually with a scanner.

I have the same car. The cooling fan activates at 227F. Only one fan will engage at this temp, the other one[closer to the A/C compressor] won't engage unless the A/C is working. Try charging the system with half a can of refrig. It'll be tough retrofitting to R-134A, the LOW PRESSURE connector is under the air box pointing sideways about an inch from a large bracket. Try and find a 90 degree adapter of some type and go from there.

Does it not run at all? Or does it only run after the fiero gets really hot (like sitting in traffic on a 90 degree day)?


But a low-temp fan switch (sensor), which causes the fan to turn on at a much more reasonable level. I think the stock switch doesn't turn on till it reaches 235 degrees or something.

The switch/sensor is located near the top of the engine (on passenger side end of engine area, opposite end of the throttle body).

Buy it here (or other places have them too)
http://www.rodneydickman.com/n20.html

You should be able to see where it installs by matching up the new part with the old, pretty easy operation. A little coolant might squirt out, so only do this when the engine is cold.

Hope this cures it

The cooling fan does not come on until the engine temp reaches 229 degrees. it is controlled by a cooling fan relay. Cheeck for power at the fan motor and check the relay. The A/C. If yuor a/c system is low on freon the low pressure switch on the accumulator will not complete the circuit for the clutch. Check the charge, voltage present at the clutch or the low pressure switch. You can install a jumper in place of the switch to test.

Hello. First, it is probably that the clotch in the coolin fan isn't working. When the coolin fluid is warm, the temperatur put it in work, and the fan works rapidly, when the temperatur lows, the clotch loose the fan an is waiting the warm up again. But your Jimmy don't have the coolin fan in the principal belt, it have an electric coolin fan. In that case, your problen is for a low level of coolin water, or the relays of the electric fan don't work properly.
Finaly, my english isn't good, because I speak in spanish, but if my bad english solves your problem, i'm geting so well. I working every day in electronics cars, and that is the basic metod of analyse that I use.

Hi micro0711, the fan (which I assume is electric) works off of 3 corresponding pieces of equipment: the rad,the thermostat and the coolant temp sensor so if you have a 180 deg thermostat the coolant would circulate through the engine and generate heat once the coolant temp reaches approx 180 deg the thermostat opens the coolant temp sensor signals the fan to engage removing the heat from the radiator cooling surface maintaining a safe operating temp. If you find your temp is rising check to be certain there is power to the fan and also that the thermostsat is operating,hope this helps good luck

you dont have enough gas in your a/c system. Regass and check again. The clutch work on pressure. As soon as the pressure reaches the requirement, the clutch will disengage.

I 'am having the same problem with my '94. From what I hae read they each have their own relays but I have been unable to find them.