tone40

1988 Carrera. I have the heating system controls by the parking brake lever (dial rotates from 1 to 3). But, I do not have the temperature sensor on the dash next to the heating & fresh air controls (as mentioned in the Bentley manual). So, I assume that I do not have the option for automatic heating.

When I want heat, I pull the driver's side footwell supplemental blower lever. It has always worked in the past. Until last week. I have never heard the blower fan work for the passenger side lever.

I can hear that the driver's blower motor is not operating. I do feel a small amount of heated air entering into the cabin (when I pull the lever), but it is not assisted by the blower fan. I tried the blower lever again today and the fan did operate for a few minutes before it went off. Did not work anymore today.

I tried the automatic heat, but I hear no fan noise. Nor do I feel any heat. I have never tried it before, so I do not know if it is operational.

Where do I start to diagnose the heating problem? I checked the stick fuses and all are intact. I tried all the operations when the car was at operating temperature.

Thanks.

rusnak

Check the heater relay in the engine compartment. You can pry the cover off and inspect the contacts. The heater motor inself may also be bad. Check for 12v at the heater blower plug. The footwell blowers wont work if the engine compartment blower is not running.

Pavegeno928

If the dial labeled 0, 1, 2, or 3 behind the levers is on zero (off), when you raise either or both levers between the seats, the engine compartment fan is the only one that comes on and provides heat either up or down depending on the position of the red lever on the control panel to the left of the radio. Your referring to the red levers in between the seats as "footwell supplemental blower levers" is incorrect. The levers only turn the fan in the engine compartment on or off.

If, and only if, either or both red levers are raised, moving the dial behind the parking brake out of the "0" position to either "1,2, or 3" will turn on the footwell blowers located behind the carpeted panel beneath the driver and passenger side air vent where the air conditioned air comes out also. However, if your engine compartment fan is dead, the footwell blowers will not blow even thought there may be nothing wrong with them as power flows from the engine compartment fan to the footwell blowers only if the engine compartment fan is running. This explains why turning the dial to 1, 2, or 3 will not turn on the footwell blowers even in a perfectly functioning system.

When I first bought my 88, none of the three fans were working (engine compartment, and both driver and passenger footwell blowers). However, with the car in motion, I would get heat when either or both of the red levers were raised and it got quite warm so I didn't realize I had a problem for the first few months. Once I got the engine compartment fan replaced, one of the footwell blowers worked and one did not. A new footwell blower resulted in all three fans working perfectly leading to an awesome heating system making top down drives in the cold weather a piece of cake.

There are several threads on how to check the electrical contacts under the red levers which turn on the engine compartment fan as well as removing the panel under the driver and pasenger a/c vents to check the fuse on the supplemental footwell blowers. I believe there is a fuse in the engine compartment for the heating system as well. It's one of the three fuses on the left rear electrical tray that is covered by the big black plastic shroud held in place with a wing nut.

Hope this helps. The heating system on our 88s is awesome. Good luck.

theiceman

i have seen a lot of these autoheat threads recently. i think we need a consolidated thread with all the info . i don t have auto heat or i would do it . We have a lot of information about this subject but it seems scattered. Anyone feel like taking up the task ?

1986 Targa

Hope this helps.

http://forums.pelicanparts.com/911-9...blowers-2.html

http://forums.pelicanparts.com/porsc...ml#post6250962

http://forums.pelicanparts.com/porsc...y-how-fix.html

http://forums.pelicanparts.com/porsc...ic-feeler.html

http://forums.pelicanparts.com/porsc...-70-cents.html

http://members.rennlist.com/imcarthur/heattrouble.htm

http://www.porschenet.com/bruns02.html

http://forums.pelicanparts.com/porsc...uel-lines.html