rickjaffe

winter is coming to Norcal and I want to try to get my heater working on my 87 928 S4.
My air conditioning works great, but I only get ambient air with the heat on (and ac button off).
I recall being told that there's a flap motor which might not be working. maybe it's in the passanger side kick panel?
I've searched and couldn't find anything about it.
is there a test I can do to make sure that's the problem before I order the flap motor or whatever the thing is which I assume closes the hot water valve which may be what I was told?

hacker-pschorr

Tell you want, I'll send my 87 out there, you send me your car and we will call it even.

I cannot turn the heat off....

It's Diamond Blue Metallic, very pretty.

rickjaffe

you need the heat alot more in frigid Wn than I do in Norcal. I like diamond blue. I dislike my color, going to repaint to casselot, oasis or other kind of lightish red rasberry. thought about ice blue, but my interior is maroon and white.

hacker-pschorr

What color is that, what does the door jam say? What kind of condition is it in?

Bertrand Daoust

Are you you sure the heat valve is not tied close?

Some owners do that to make sure that the heater core doesn't get coolant when the car is shut off.
That way, the system gets cooler faster after you re-start the car.

rickjaffe

no it isn't that. I recall that some kind of switch was broken and I had the choice of heat or a/c and since I lived in houston, I chose a/c. I also recall being told that I could manual open it with a screwdriver somehow, but I never tried, that's why I think it's the flap motor or whatever it's called.

rickjaffe

better the devil you know. I put a ton of money into mine. still needs recovered dash pad and paint. hopefully the cars will eventually be worth something.

soontobered84

Sounds like a vacuum solenoid(?) from your description. Somebody jury rigged your passenger footwell flap, maybe(?) and the screwdriver is supposed to hold open the flap?

Vacuum solenoids are not hard to fix at all.

rickjaffe

is there somekind of written procedure somewhere?

Bill Ball

A likely cause of this symptom is the setting motor. If the setting motor is not operating, you will get either cold air or heat but not both, depending on which position it is stuck in. It controls the mixing flap and the electrical signal to the vacuum solenoid for the heater valve.

The setting motor is on the lower left side of the heater/evaporator box. You can see it by removing the left side panel on the center console. You can test it by moving the temperature control slider [engine on] and observing whether the arm, which controls the mixing flap, moves. If it doesn't, then it is broken. Or you can observe the end results, the mixing flap moving and the action of the heater control valve. With the engine running, if the setting motor is stuck in the "no heat" position, the heater valve will be pulled closed by vacuum and there will be no response to the temperature slider position.

Sometimes the setting motor can be repaired by replacing the transistors inside.