Footwell blower motors stuck on?

[getluky]

I have an odd issue where even if I turn off the car, the front footwell blower motors are stuck on. I've been disconnecting my battery to avoid drain while parked, but I just disconnected the harness connectors going to them to keep them off while I figure out what's up. Car is a 1987 911 Targa. The electrical system has been hijacked by a bad aftermarket alarm installer at some point in its history, but I've had the car for about 6 years and this is the first time I've seen this particular problem. Any ideas on where to start? Most of the troubleshooting info in the Bentley is about the automatic heater system, but I think I have the manual one... so I'm not sure whether it's still accurate.

[DRACO A5OG]

Check the small switches under the levers, there may be debris caught there causing the switch to remain open ergo Foot Blowers on. It will also turn on the engine bay heater motor as well.

[MH911]

There's a pretty good article in this January's issue of Panorama about the heating systems of our air cooled Porsche's. It talk's about how the footwall blowers don't come on until the engine blower does. In the Bentley, the schematic (p970-50) shows that all the wiring goes to a "Heater Control Unit". No idea where this unit is. Sorry I couldn't provide you with more help.

I have been looking into why my manual controller ( between the seats ) doesn't effect the footwall blowers.

[Hodgey]

Originally Posted by MH911

There's a pretty good article in this January's issue of Panorama about the heating systems of our air cooled Porsche's. It talk's about how the footwall blowers don't come on until the engine blower does. In the Bentley, the schematic (p970-50) shows that all the wiring goes to a "Heater Control Unit". No idea where this unit is. Sorry I couldn't provide you with more help.

I have been looking into why my manual controller ( between the seats ) doesn't effect the footwall blowers.

I look forward to reading it when it comes......in February

[MH911]

Yeah. I know. I got mine Saturday.

[DRACO A5OG]

Originally Posted by MH911

There's a pretty good article in this January's issue of Panorama about the heating systems of our air cooled Porsche's. It talk's about how the footwall blowers don't come on until the engine blower does. In the Bentley, the schematic (p970-50) shows that all the wiring goes to a "Heater Control Unit". No idea where this unit is. Sorry I couldn't provide you with more help.

I have been looking into why my manual controller ( between the seats ) doesn't effect the footwall blowers.

HCU is in the engine bay near the 1,2,3 fuses a grey metal retangular box.

Your year has fuses at the foot blowers, remove foot kick panel and next the foot blower you should find the blown fuses.

[MH911]

Originally Posted by DRACO A5OG

Your year has fuses at the foot blowers, remove foot kick panel and next the foot blower you should find the blown fuses.

The blowers are working. I just don't notice a change to the sound level of the blowers when I switch to a different setting. Off, 1, 2 or 3 all produce the same pitch. So, I think the fuses are good there.

[DRACO A5OG]

Oh that is strange, On mine 0-1 are same 2 is mid level & 3/Defrost are full speed.

[Mysterytrain]

Speeds one and two are controlled by the ceramic resistor in the trunk behind the glove box. The high speed position bypasses the ceramic resistor and is fed 12 volts via a relay in the trunk. If you are stuck on 'high' then the relay contacts could very well be fused together and appling voltage continuously.

[DRACO A5OG]

Well Arcadia? Did you fix it?