jet911

I own an '86 911 Carrera. On the way to work today I turned on the heater (I have the electronic switch between the seats - no levers). The side vents, defrost and foot wells were blowing hot air as they should. As I came off the freeway to a stop light, I noticed there was a very loud almost screeching noise coming from the engine compartment. I turned the switch from red (7) to white (4). After a minute the sound almost quit, but not quite. I turned the switch back to the red and the noised started again and then I smelled the dreaded smell of something electrical overheating. Before I could turn the switch off, the blower quit working. Now when I turn the switch on, nothing happens.

Have I blown out the blower motor? Have I blown out part of the electical system as well? Why does not the two side motors come on now? Any ideas? Help!

Regards,
Jim
'86 911

Trak Ratt

Definitely sounds like the blower motor on the engine. The fuse finally went as the bearings seized. Just disconnect the motor, replace the fuse & your heater will probally still have some output, the earlier 911s didn’t even have the extra blower. That blower motor is easily changed.

jlkline

Sounds like the motor has died. If you test it and it is in fact done, I bought a "made in Germany" replacement from Partsheaven that was about 1/2 the price as the Bosch original equipment.

jet911

Thanks for the input gents.

On my way home tonight I decided to mess with the switch (turn it on and off) to see if anything happened. I turned it all the way to the right (red (9) I think), I could hear a humming sound in the side motors but no real thrust of air. Then when I hit about 3500 RPMs, all the fans came back on (couldn't tell about the one in the engine compartment). I let off the gas and they quit, step on the gas, hit 3500 RPMs and on they come again. I could still smell the burnt electrical smell. I was shocked that the fans came back on if only for a second. I did check the fuses and as I suspected, there were none blown (at least in the trunk compartment).

Any clues about what the heck is happening here? Don't want to purchase a blower motor and that not be what the issue is. Any way I can test the blower motor? Thoughts - Ideas????

Regards,
Jim
'86 911

George 86T

Don't buy a motor just yet. Pull the motor out of the engine bay--dismantle it and lube the bearings with oil (not just WD40) and while in there check the brushes to make sure you have some usable life left in them. MOST screechers just need a little TLC to keep them going. It's possible it's burned out but more than likely just needs the bearings lubed.

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jet911

Thanks for the suggestions and help. I'm thinking of doing the repair this weekend as the flakes are starting to fall here in SLC, UT.

Another questions. Do all the heater fans (footwell and main blower as well as aux fans in the front) run off the same electrical circuit? When my heater blower quit, the other fans seem to have quit as well. When I turn the **** between the seats to 9/10, I can hear the flapper boxes open (I beleive that is what I'm hearing). I do get heat in the cabin after a few minutes, however no forced heat (very similar to the old VWs). The other odd thing is when I get to very high RPMs, about 5,000, I hear the aux. fans (I beleive) in the front kick on (behind the front kick plate). When I replace the blower motor in the engine compartment, will this compete the circuit and result in all fans working properly, or did something else get toasted when the blower motor went? Suggestions or other similar experiences and solutions are greatly appreciated.

Regards,
Jim
'86 911