Engine Cooling Fan Operation

[BOPE]

I have a 1980 911 SC, which is new to me and I have a question about the engine cooling fan operation: Is it thermostatically controlled, or does it run all the time?

Thanks!

Jason

[Funracer]

All the time unless the belt is broken.

[porschedude996]

Jason, it is a direct drive off the crankshaft pulley. If the engine is turning, the fan be blowing.

[A930Rocket]

If it’s not turning, stop driving.

[BOPE]

Ok, so the fan I'm talking about is electric and is positioned in the upper left side of the engine. So, according to a recent post on Rennlist, this fan is part of the heating system and should run only when the heater levers between the seats are raised. Is that correct?

Jason

[Ryan_Cunningham]

I think you’re referring to the heater blower.

[REVerend]

Originally Posted by BOPE

Ok, so the fan I'm talking about is electric and is positioned in the upper left side of the engine. So, according to a recent post on Rennlist, this fan is part of the heating system and should run only when the heater levers between the seats are raised. Is that correct?

Correct… if the heater blower doesn’t work you will still get a good amount of warm air from the duct off the left side of the engine shroud. It goes up the left side duct through the big plastic tube to the heater blower and then out to a splitter that has hoses that run down to the heat exchangers under the car.

In my 911SC the fan kept blowing fuses and I chose to do a “heater backdate” which removes the electric fan entirely and just uses air coming off the shroud ducts. It seems more than adequate for my purposes and clears up a bunch of space on the left side of the engine compartment.

If you are interested in seeing a non-purist solution this is my heater backdate thread.


https://forums.pelicanparts.com/porsche-911-technical-forum/1177442-adventures-back-dating-heater-83-911sc.html

[porschedude996]

That fan is activated/energized when the micro switch is closed when either of the heat levers by the parking brake. My 1983 motor was totally worn out when I got the car. I think the air from the big cooling fan may spin the electric fan when unenergized leading to bearing wear. In addition the heat the motor is exposed to.

[BOPE]

Thank you for all the informative replies; I learned quite a bit. This is my first air-cooled Porsche, so I have a lot to learn about the cabin heating system and engine cooling.

Jason

[BOPE]

So, if I decide to delete my electric heater fan, has anyone found an aftermarket left side heater duct that fits?

Jason

[REVerend]

Originally Posted by BOPE

So, if I decide to delete my electric heater fan, has anyone found an aftermarket left side heater duct that fits?

Jason

Would love to know that myself… people say get a 930 heat duct but those seem to be a bit hard to find now. I adapted the plastic SC left side duct but would prefer to get the more correct version.