footwell heaters

[opie]

My 86 911 footwell heaters will not run, I have checked the power at the switch between the seats and there is no power there. Ran power to the blowers and they run. Im not sure where else to check for power, fuses are all good

[wwest]

The footwell heat/defrost airflow boosters will not run unless the engine compartment cabin heater blower is operating. Slightly lifting either of the 2 heat level control levers will start the rear blower via the switch connected to the 2 yellow wires. The Heat Controller module uses a reed relay setup to confirm that the rear blower is running, drawing the specified current flow. A low battery voltage can result in the rear blower not drawing enough current flow.

[opie]

Ok, when I raise the to leavers up, the engine compartment blower does not run.

[wwest]

Make the engine compartment blower runs with 12 volt applied. If it isn't one of the fuses in the engine compartment then you might be looking at $$$$ to replace the heat controller module.

[Jack Stands]

There is a workaround for the relay that allows the front blowers to work without the engine blower working. I don't have the link, but it should be searchable on this forum.

[m110]

You need to jump the reed switch in the relay to bypass the engine compartment blower (if it is non functional and you want the front blowers on). Of note it is different for 88 89 and maybe 87

[opie]

Is the reed switch the same as a relay. I'm not familiar with a reed switch.

[Jack Stands]

The reed switch is inside the heater relay in the engine compartment.

[wrxnofx]

Before you break open the relay and jump it, make sure the engine blower motor works. If that motor doesn't work the footwell blowers won't turn on. If you don't have a way to apply 12 volts to the engine blower, just pull the connector to it, take a 9 volt battery, and touch the terminals on the motor (you'll have to feel your way as the 2 terminals are just behind the blower housing). If the battery doesn't cause the motor to spin, chances are the motor is cashed and you'll need to find a used one on here.

[crownarch]

Do a search for this thread "Help! Does anyone understand the footwell blower circuit?" It explains everything on how to determine if your relay is bad. You will also find the schematic for a work-a-round using inexpensive relays for about 7 bucks. I used the schematic for two relays and no diode and it works just great.

[NYNick]

Careful. #1) that relay costs $400, so when you attack it, make sure you do it carefully, and you know what you are doing. 2) There are two different ways to jump that relay, and it depends on which relay is in your car....apparently Porsche changed the relays around 86-89, and depending on which one you have....

There is a great thread with great pix...here.

nick

[NYNick]

Here it is...read it all, but look at my posts around #113.

http://forums.pelicanparts.com/porsche-911-technical-forum/388445-carrera-removing-engine-compartment-heater-blower.html

[opie]

I took the engine compartment blower out and put 12 volts to it, nothing. So what I understand is, if this fan is not working foot well blowers will not work, is this correct?

[wwest]

Yes, no current flow through the cabin heater blower commutator, the reed switch does not close, no footwell blower power.

[crownarch]

If your blower motor is bad read this thread - http://forums.pelicanparts.com/porsche-911-technical-forum/97297-carrera-replacement-heater-blower-long.html

[911M491]

Discovery bad reed switch and secondary coil relay in 88 911 with manual system. All blowers test and fuses good. I replaced the secondary coil relay with a radio Shack 6pin dpdt mini relay. I jumped the reed switch. Footwell blowers on all the time regardless of engine heater levelers position. I want to turn the fw blowers off when not using the engine blower. Any suggestions? Manual switch. Change 0 to really mean off.?

[86 911 Targa]

Here's a thought.

[911M491]

The issue is can a switch be added or alter the 0 in the existing switch to be off. I only want to run the Footwell blowers when the levelers are up and the engine blower is on.

[m110]

Originally Posted by 911M491

The issue is can a switch be added or alter the 0 in the existing switch to be off. I only want to run the Footwell blowers when the levelers are up and the engine blower is on.

You can't just jump the reed switch on an 88. The relay is different for that year. I believe the part numbers are the same but the circuitry is different to allow for an upgrade that kept the blowers moving slowly at all times so they don't seize.

Read:
http://forums.pelicanparts.com/porsche-911-technical-forum/388445-carrera-removing-engine-compartment-heater-blower.html

especially post 114

I had someone skilled modify my relay exactly like that and it works great as described.

[911M491]

Thanks m110. What isn't clear to me with this mod is can i still use the engine blower? Can I get the fw blowers turned off when neither blowers are used? You stated that the 88 fw blowers always spin correct? I don't want a new $ 400 relay that still doesn't work.