Automatic temperature control
 

Hi,

My 1987 951 is equipped with the automatic climate control system.

Now, if I understand the instruction manual correct, the systems should heat or cool the interior temperature to the temperature that I set on the dial (cool if the A/C button is pushed of course).

Now as far as heating is concerned (up here in Michigan we're already getting to temperatures where a little heat is quite comfy) the heater only blows hot air if I set the dial to its maximum temperature. Any setting lower than this does not have any result as far as getting heat (the A/C has been turned off of course).

When I turn the windshield deforst button, the heater immediately blows hot air, regardless of the position of the temperature knob or A/C switch.

Is this a familiar behaviour? How about temperature setting with the A/C on, in case I want to cool the car's interior to a desired temperature?

Thanks a million?

PT

Ahhh Michigan in winter... I remember it well (I grew up in Sterling Heights) - which is why I now live in Florida.

The defrost button will overide any other setting, blowing hot air at the windows, through the doors, and across the rear hatch (thats what those holes in the back are for)

The temp knob is supposed to control the mix of warm and cool air - it is controled by temperature sensors in the dash. You shouldn't get full blasing heat unless the temp knob is pegged all the way to hot. That said, you should notice a temp difference anywhere across the scale.

If you aren't, either your temp selector knob is bad, or your temp sensors are bad.

Verify that the temp is changing as you move the knob from cool to heat - it should get progressively warmer. The most common failure is temp sensor.

AFJuvat

Two things to check:

1. Proper operation of the servo controlled mixing flap. It’s located just above where you right foot sits in the drivers foot well, behind a plastic cover. Remove the plastic cover and turn the car on, move the climate dial to both extremes. That motor should move the mixing door all the way open and all the way closed.

2. There is a climate sensor behind the glove box. This sensor has air drawn over it by a miniature fan; this samples the cabin temp and sends the signal to the climate panel that operates the air flap motor. Sometimes this sensor gets covered in lint or hair and needs to be cleaned before it reads accurately.


Hope this helps.

BTW on another note, even when the system is working tip-top it's not very accurate in my opinion.

Geesh! I just move the slider on my 83 a bit!

Wow
 

Thanks for the hint!

Re: Wow
 

Sometimes I wonder if the greatly improved air handling of the late model 944's is worth all of the gizmos that make it work.

heheeh you should see what it costs to replace the unit - there was MUCH rejoicing when Porsche finally allowed the switches to be sold as individual parts.

AFJuvat