Porsche Enthusiasts Club Forum

My air con dosnt work but thats not the problem!!! On my 928 s4 1987

The heating dosnt get very hot, its a nightmare in this cold weather, any ideas whats wrong?

Many thanks Mark

Hi Mark

Not sure if this helps but I have no aircon...all stripped out, and my heating is roasting hot when needed....

All the best Brett

Hi Mark
I am having the same problem with my 87 s4 and on further investigation i have found that the heater flaps have been cable tied in the fully open position . they should be electronically controlled .the linkage rod has broken on mine so i shall try and make up a new one.
This could be the same problem with yours
When mine is warmed up it does not get into the middle section on the gauge
Cheers Grahame

Grahame, thank you for your advice!!! i will have a look over christmas

All the very best Mark

Hi Mark

Sit in quiet garage or quiet street, engine off, ignition on. Start with temp slider in full cold position (bear with me - I know you're chilly).

Move slider to full hot. Can you hear motor running just above your left knee?

If you hear it run, stick head if footwell and shine torch up into area where driver parcel shelf meets console. Do you see motor arm rotating when you slide from cold to hot? Is metal arm attached to motor?

Please report back on results!

Cheers

Adrian

Hi Mark
Sorry i think i have misread your problem i thought you meant the engine was,nt getting up to temp and that your heater was not getting warm enough .as Stratford Shark says it may be the heater slider motor mechanism
Cheers Grahame

Adrian, sorry to sound stupid the fan is running, but i cant see the motor.
Theirs a black plastic box with a silver arm is that anything to do with it?

Thanx mate Mark

Grahame, thank you for your interest All the very best Mark

Hi Mark

Not at all - I should have been clearer.

The motor I referred to is mixing flap motor, which adjusts amount of outside air and air warmed by heater matrix blown into cabin.

Keep fan off to help listen for sound of this motor.

Yes you've spotted the mixer motor!

Is there a thin metal rod attached to silver arm? That's connected to mixing flaps at top end.

If rod is present, is the silver arm rotating when you move the temp slider from full cold to full hot, then reversing when you move back to full cold?

Cheers

Adrian

Adrain, what are you doing too me? lol
im laying in the car upside down in the dark with my dressing gown on lol

the fan isnt running if i just adjust the temp, also the bar dosnt move

Thanks Sir
All the very best Mark

Sorry to put you in uncomfotable position Mark!

The fan only controlled by rotary knob. You can keep it off during these tests.

So the setting motor (black plastic box with silver arm) doesn't move when you adjust temp slider?

Is rod attached ok to short silver arm?

If motor not moving at all then you may need replacement, or existing can be repaired (simple transistor comparator circuit inside - a tranny probably blown).

Adrain, Thanks mate!!!
The knob you turn dosnt do anything So maybe its just the knob?

Other wise what should i ring Simon for in the morning?

All the very best Mark

Knob/blower speed not related to actual temp control system.

Does mixing flap motor move when you move temp slider between extreme positions?

Is mixing motor connected to thin metal rod?

Adrain, im not sure what i should be looking for.
Im going to have another look, should i be looking at the metal rod thats connected to the small black box? to see if its connected at the other end
All the very best Mark

Hi Mark

Yes you are looking at the right box. The black plastic box houses the setting motor for mixing flaps.

When you have a look let me know:

- when you move temp slider between max hot and max cold, what does the arm driven by black plastic box do?

- is metal rod connected to end of arm?

For this test ignition should be on (warning lights lit on dash), but engine off.