Kevin Michael

man, i think my s4 is mad at me. have no idea why, as i pamper the spoiled brat constantly! seriously, though. this morning i take her for a quick blast, get home, shut 'er down and the fans are still on which is normal, but 15 min. later they are still on! weird part is i can open any door, hood or hatch and they shut off. car is an 87 s4 with an extensive service history.
i disconnected green wire from the intake sensor and they shut off. i cleaned every ground i could find just to discover all had already been cleaned. i thought i would take a shot here thinking maybe someone here has BTDT. thanks to all in advance.
kevin and laura

Kevin Michael

bumpity-bump.(sorry)

drnick

dont know if its the same on the S4 but my S2 had a faulty temperature switch, the one on the right front of the radiator. these fail 'on' and cause the fan to run continuously.

jserio

Not an answer but that little plunger on the pass side of the engine compartment is the fan cut off for when the hood is opened. Knowing Porsche it probably has 10 other functions also. I guess there is a cut off or sorts for doors and hatch as well. My fans run constantly also. They run with the accessories on but at least they are shutting off now with the key off.

blau928

You most likely have a bad Air Temp Sensor.. It's the one that bolts into the intake runners.... Test it by jumping the hood switch on the passenger side fender, and disconnecting the Temp sender... If it stops, then just replace.. cheap part.. If it's your fan controller, then you need to cough up some cash unless you find a used one...

I replaced my Air Temp sensor last year as well.... Similar problem..

Good Luck,

Kevin Michael

nick, even with the key off?
richard, i performed the test you prescribed and the fans indeed stopped. i will replace the air temp sensor. how do i test fan controller as a preempt to changing air temp sensor?

T_MaX

On automatic 928 cars the trans temp switch is wired inline with the intake air temp switch.

I replaced two intake switches before I learned this! Don't let it happen to you

The wire for the trans temp comes up through the battery box and connects close to the center of the car just behind the rear air unit (if so equipped).

"any door, hood or hatch"

Hood yes, but the doors and hatch should not have any effect!

Kevin Michael

[QUOTE=T_MaX]On automaitc 928 cars the trans temp switch is wired inline with the intake air temp switch.

I replaced two intake switches before I learned this! Don't let it happen to you [/
hi curtis, mine's a 5 speed.QUOTE]

T_MaX

Didn't see it in your sig.

Lil Mama

Better your S4 to be mad at you than your WIFE!

WallyP

Normally, the radiator temp switch, the HVAC temp or pressure switch, and the transmission temp switch (if present) are wired thru the 15 bus, so they only can make the fan/fans run if the ignition switch is on.

The intake temp switch (if present) is wired thru the 30 bus, so it is always capable of making the fan/fans run.

Potential problems vary with model year, but in general, if the fan/fans are running with the ignition switch off, it is the intake temp switch faulty, the fan relay (some years) stuck on, or the ignition switch is faulty and not turning completely off.

blau928

Kevin,

See Wally's comments above as well... The only way I know to test the controller, is by swapping it for a known good one.. The point you made about any door, or hatch having an effect on the fans sounds like someone may have wired the hood switch into the interior lamp circuit or something like that... The doors or hatch should have absolutely no effect on the rad fans....

Kevin Michael

thankyou wally and richard!
with that info. i think i can get it straightened out.

SharkSkin

PO alarm install could account for hood, doors, & hatch all affecting this. Does your interior light come on when you open the hood?

Kevin Michael

hi, dave a.,
that my friend is an intelligent observation! i never thought of it. there is an A.M. alarm installed by PO. can you tell me more?