My car is 93 940 4 cylinder with bosch ignition.
With the a/c on on hot days i turn the ignition off and the electric radiator cooling fan will continue to run for about 3 minutes before tuning off.I have noticed that if i turn the ignition on and off the fan will turn off, its intermittent. Things i have done i changed the fan relay and it didn't help. When the fan was running i pulled the connections off the 3 A/C pressure switches (violet,brown, grey)and the two temp sensors off the side of the engine and the fan still wouldn't stop.
I had a spare ignition switch and radio suppressor relay and put those on and it didn't help. Any suggestions could i have a bad solder joint in the A/c control panel at the dash that could be causing the problem.

Fixed it put in a new engine thermostat.

Hi volvo426,

Thanks for updating us!

Amarin.

Hi,

Is this a new occurrence or it was like this ever since you own the car? Did the car has any A/C works on it recently before this occurred?

I had similar experience of this while owning a 940 with low pressure turbo (LPT) last time. Even with the ignition off the fan could just start on its own a few minutes afterwards. I think its ECU controlled but haven't see any documentation regarding this. At one time the fan ran for about 15 minutes. I think its to cool down the turbo.

My current non-turbo 940 haven't got this issue. The fan would be off as soon as ignition is off.

Only the grey and brown pressostats switch on the fan directly (via the fan relay) without any intervention from the A/C control panel. If disconnecting the pressostats would not turn off the fan then it must have been the ECU.

Check for any OBD codes. Check also if it helps to let the engine runs for a while before switching off (cool it down first before off).

Amarin.

Yes just started i have had the car four two years. It even happens without the A/c on as you described above. I pulled the middle plug from the relay near the battery and it would turn off and back on when i plugged it in. the only way to stop the fan was to turn the ignition switch on and off a few times.

Dear volvo426,

Hope you're well. According to the Wiring Diagram for the engine cooling fan (p. 28), the ignition switch is not part of the cooling fan's controls. The ignition switch is exonerated.

The cooling fan is powered directly from the battery. The cooling fan can be activated by the air-conditioning pressostats and - if a car has Rex-Regina ignition/engine management - an in-radiator coolant temperature sensor.

As your car has Bosch ignition/engine management there is no in-radiator coolant temperature sensor. Thus, the fan relay may be "on the way out": it may be sticking in the closed position. I realize that you replaced the fan relay. Unless the replacement is brand new, it is possible that the second used unit may not be in good order.

Hope this helps.

Yours faithfully,

Spook

Fan stayed on again even with not using the A/C. The relay at the battery if i pulled the center plug out the fan would stop so some is feeding it. ?

Hi,
I think you need to check the coolant temp sensor, thermostat and radiator fan relay. It is getting hot in Malaysia and maybe one of these items is going bad. If it is the ECU you will need to replace it or buy an aftermarket radiator fan control unit
Gus

I know you have a 900, but if a '93 240 is any example, the fan is controlled by just one pressoswitch. It's located on a branch parallel to the A/C line (think of a railroad siding) along the lower unibody stringer (sort of like a frame, if it wasn't unibody) on the right side of the engine, just beneath the oil filter and alternator.

That pressoswitch might be sticking closed.

As above, I don't know if the '93 240 is a useful comparison, but just trying to help.

Good luck.