fbgh2o

I just finished replacing the dash in my 1986 951 and now that I have everything back together and working, almost!

I have encountered a strange noise from within the dash which was not there before. For lack of a better description it sounds like a very loud servo motor, a stuck electrical or fan motor, or a relay gone bad. The noise is emanating from the centre portion of the dash and I think it is louder in the passenger foot well near the hvac system. The noise occurs when you turn on the ignition (not at the first position that the key can be moved, but at the second one where all the idiot lights come on).

Other info -

If you put your ear next to the temperature sensor on the dash you can hear it very clearly

When I pull Fuse 17 which controls the heater the noise stops.

The battery has been out of the car for about six weeks and I just reconnected it.

I swapped the heater control unit with another one from a 1986 944 N/A. I believe they are identical.

I checked the operation of all of the servos in the driver's foot well and they operate fine so it is not the heater controls

Any thoughts on what it might be?

Rock

Mebbe you got a loose cable or wire stuck in the step motors of the fan.... or wait I have no idea

fbgh2o

Nothing appears loose. I have gone over everything with a fine toothed comb and have not been able to find anything mechanical that seems to be causing this.

Is there anything in the heater mechanism that would be sensitive to a different control unit and cause a problem?

Or is there anything in the heater circuit that could cause this make such noise?

Luis de Prat

I would double check this!

fbgh2o

Luis

Are there any difference between the two? Same functionalities on both.

Thanks

Luis de Prat

Fergus, I'm not sure, but I remember reading about differences between certain years in the Factory Workshop Manuals. If you have them, you should double check for possible differences.

http://www.cannell.co.uk/Manuals.htm

fbgh2o

I have the time, so I am just going to switch back and see what happens. It is the logical solution as I was super careful to make sure that nothing was binding on anything else.

hosrom_951

A couple of things to check.

Two vacuum servos near the glove box. One clicks for the re-circulation button and the other clicks for the heater valve.

There is a temperature sensor deep down behind the glove box, on the fire wall. There is a hole on the dash for it, there should be a tube. Just follow it and make sure that the fan is not spinning and hitting something, or that could be the fault.