It's too cold ..... So I must fix the rear blower ...

[ZV8888]

Hi,

The fresh air rear blower motor in the engine bay has two wires coming out of it that are not connected to anything. I suspect this may be a contributing factor to it not working. The problem is that there are no wired in the vicinity that look like they will connect to them.

What wires should connect to them? Where might I begin my search for them?

Thanks

[pozee]

No idea what year car so no idea what resources to look up to help.

Make sure the blower motor works before hooking it up to vehicle wiring. Wire it up separately with a 12v source.

[ZV8888]

That was silly of me not to state that it is a 911 SC 1978

Help is appreciated

Yes, Pozee, I will check it works first, but even if I have to buy a new one I'll still have to figure out the wiring.

[psalt]

There should be a white T shaped plug, at the end of a yellow/black stripe wire and a brown wire, coming out of a wiring harness that goes under the airbox. If the motor does not respond to 12v at the black wire, you can try taking it apart. Usually they die because the switch is misadjusted or left up and they run continously. The bearings are an odd ball and cup design, you can used rod end bearings to rebuild them, and the brushes can be replaced. After you fix the motor, make sure the switch between the seats is working correctly, they can't handle continous running.

[911Mac]

if you test the motor by hooking it up to 12V, don't use small diameter wire for your test. It can't pull enough current to make the motor run even if the motor's fine. There's also a relay that's part of the heater blower circuit.

[ZV8888]

Thanks for the advice and tips guys. I'll get stuck into it as soon as I can. I might try to remove the motor and put in a join between the engine fan and the fresh air intake. Then I can proceed at my leisure.

[greg bradbury]

Hi,

Not sure about the wiring. the connector should be right there. perhaps someone(PO butcher) has "tidied things up" by cutting it off. look for the wire stubs

Other things to look at also.

I have an 83 ROW car which had heater problems. I did the following-

1. Check the motor spins feely. Mine had a worn front bush. I replaced this and it chewed out really fast as the shaft was pitted. I ended up putting in a small ball bearing. fixed.

2. move the balance clips (on the fan) around to rebalance the motor. this makes it a lot quieter and smoother.

3. if you have the temperature controller down near the handbrake make sure the lines back to the control flaps are free. Mine were ceased up with dry grease.

4. Check the connection to the temperature sensor up near the rear vision mirror its a small plug and socket arrangement and on my car it didnt plug in all the way . i shaved some of the plastic on the plug so that it went in all the way. If the connection is not good the heater will run full blast and melt your socks.

The heater controller should make a clicking noise when the dial is rotated to the hot positions above 6. this is the controller motor pushing the flaps closed.

the heater system is pretty complicated but when it works as designed its good. the problem with the air cooled cars is that when the speed goes up so does the heat. the controller helps overcome this qute well.

the heater is a small thing but when sorted out makes those cold days comfortable. and boy does it get hot! and quick too. Best heater in any car ive owned, next best was my trusty volvo. ahhh those volvo days.....

good luck

brad.

[porsche930dude]

do a search on heater backdate. you can eliminate the blower entirely

[SteveinTO]

The connector for the blower motor is probably there. Mine had also been disconnected and fell down into the tangle of wires & hoses. Had to remove the blower and the big air supply tube and a heater tube or two. Bet you find the plug a way back in there.

It was probably unplugged because the motor was broken or a bearing went out so it made a squealing noise. On mine, the winding had broken causing a failure after 20+ years. The fan is readily available from our host, although a bit pricey. Several others have done threads about bargain fixes from the Grainger catalog, but I like the OEM style myself. Perfect fit. No tin snips. No drilling. No glue.

[ZV8888]

Thanks for all the advice the tips. I'll be back on the job this Saturday. I appreciate the suggestion that I should remove the blower entirely, but it is a bit cold in Ireland for that. Now if I was lucky enough to live in California then I'd go for it. I take on board Greg's comments regarding the temperature sensor.

I was thinking that it might be worth considering bypassing the clever electrics and just mounting a nice switch near the temperature controller that I can use to switch the fan on and off when required. Has anybody done this? Are you happy with it?

[enzo1]

If ur blower motor , inside the housing doesnt work because of bearings etc...take it out of housing and take it to electric motor repair or alternator shop for repair, its usually really cheap