Fan remains on

[zajo]

Hello,

1990 C2 911: today while I was driving I noticed that the fan remains on even when the fan speed is at zero, though the other fan speed positions seem to work fine. The fan also remained on after I turned the car off and removed the key from the ignition, which I'm guessing has something to do with the fact that two days ago my car completely drained the battery while sitting in the garage.

Any ideas how to troubleshoot this problem?

Zajo

P.S. Note, I'm not talking about the engine compartment fan that I do know may remain on for a while after the car has been turned off if the engine is too hot.

[964TargaC2]

THis is where you need to look

Porsche 964 / 993 CCU electrical repair

[89 White C4]

THis is where you need to look



Porsche 964 / 993 CCU electrical repair

I think that fan stays for a few minutes after the car is shutdown.

[89 White C4]

Sorry did not see the bottom portion of your message.

[ToreB]

You might have a problem with the front interior fan "final stage". It's placed under the plastic cover behind the fuse box. Details are given on my DIY page already linked to above.
Cheers,
Tore

[zajo]

Thanks everyone for the replies! The final stage was the culprit. Thankfully I have a friend who is one of these electronics wizards, he brought in an oscilloscope and determined that there was a faulty transistor in the final stage. We replaced it, which cured the problem... somewhat. The fan is no longer on when the ignition is off, but it seems always on when the ignition is on, even when the fan speed control is at zero. Is this normal? As far as I remember, turning the fan speed down to zero should stop the blowers.

[ToreB]

The front fans runs on minimum 1 in the 964, even with fan control button to 0. This is normal behaviour.
Cheers,
Tore