'94 850 wagon random fan

Benoit Muto · Post by **Benoit Muto** » 04 Oct 2009, 17:08

Our '94 850 wagon (215k) was dead this AM. No juice at all. Jumped it, ran it 15-20 mins, turned off restarted ok. About 30 mins later went to use it - dead again! Connected jumpers and I immediately heard "a fan" noise up near battery (key was on -oops!) Never noticed this and it wasn't the radiator fan. Jumped car,ran 15 mins, restarted ok. Then a hung around car, after 10-15 mins fan came on again!! No key in ignition either. What is it and why all of a sudden? What can I do to 'fix' it . Thanks!

newtome 850 · Post by **newtome 850** » 04 Oct 2009, 18:05

Not sure, but it sounds related to the temperature switch. As far as I know it kicks on to assist in cooling( sitting in traffic, when air is not moving through the radiator). If it is staying on than that would drain the battery. I dont believe it should come on till after the thermastat opens though and engine is at or a little above normal temp.. Check your radiator for proper coolant level and circulation too. Hope this might help.

Post by **Ozark Lee** » 04 Oct 2009, 18:42

The ECT sensor is definitely a suspect. It is located directly below the thermostat, on the lower thermostat housing. Standard protocol is to change the thermostat at the same time as the ECT sensor.

...Lee

Post by **tjts1** » 05 Oct 2009, 01:44

Sounds like a failing fan relay to me. Next time the fan turns on unexpectedly with the engine off, disconnect the middle plug on the relay with the 2 skinny wires. If the fan stays on, your relay is bad. If the fan turns off, the ECT sensor is bad. The system is designed so that in some circumstances the cooling fan can stay turned on for a couple of minutes after turning off the engine. This happens to me after driving up Mt Baker at slow speed on a hot day from sea level to 7000 feet in 40 miles. This is normal. It shouldn't switch itself ON 15 minutes after shutting off the engine.
good luck
Justin

Benoit Muto · Post by **Benoit Muto** » 05 Oct 2009, 11:12

update:
I removed splash pan and found a fan unit down low near radiator(drivers side)
Traced black wire to spade connector near battery, disconnected and stopped fan. It is NOT the radiator fan/relay on front shroud.
Ok could this be the air pump/relay? I think I cross referenced it @FCP site. I can't seem to locate relay in Haynes manual schematics, pump is there. How would I go about troubleshooting properly??