Defrost Motor

Semba · 10-31-2008, 05:28 PM

I have a 1982 911sc. I do not have power to the engine compartment defrost motor. Does not appear to be a fuse, but questioning a relay? If not a relay then where does this well hidden wire go? I believe I just need to trace these wires to see if there is a short somewhere.....maybe......or a relay......or .....????? I was told the motor was working before it was parked for two plus years. Hope someone can help.

Gary

Aurel · Aurel's Garage

Connect a 12V battery directly to the motor, see if it spins. Could be a wire unsoldered inside the motor.

Aurel

SteveinTO · 10-31-2008, 08:58 PM

The motor in my '82 finally quit. One evening to replace if need be. Good opp to straighten out some old rubber pieces, vents & tubing & drains & the like.

Like Aurel says, make a couple leads with alligator clips and connect it to the car battery in the trunk.

Pazuzu · 10-31-2008, 09:00 PM

I just pulled my assembly out, I could cut you a deal if you need the blower and/or associated piping. PM me if you find yours is dead.

Semba · 11-01-2008, 05:42 AM

Checked the motor, it works fine. I also found a blown fuse hiding under a plastic cover in the back, but I do not have power to the wires leading to the blower motor. Also a relay labeled "Fan" near the fuse I replaced, can I bypass this to see if I get power? and how do I do that?

Scott R · Scott R's Garage

be careful here, if the fuse to the fan is blown its due to high resistance in the fan motor. This can lead to fire.

RoninLB · 11-01-2008, 08:24 AM

Factory install... my 2 manual heat levers between the seats were each also connected to a simple on/off switch. They are prone to get dirty from carpet crap. The switches control the engine fan.

sailchef · sailchef's Garage

My fan motor was intermitant, sometimes it worked, sometimes it didnt. Turned out there was a lot of dirt buildup on the tiny switch located at the levers between the seats that activate the blower. I cleaned up the switch and works fine. You can adjust this switch to come on in traffic without the heater boxes opening if you tweek it right. helps cooling in standing traffic

Semba · 11-02-2008, 04:30 AM

It turned out as I suspected to be the relay. I swapped it with the fog light relay and the motor fired right up. Thank you all for your help, I never would have known about the switches under the defrost levers. NOW....even though the motor is running, I do not notice any difference in air output to the windshild, in fact, I don't notice any at all, just like before the motor problem was fixed. Is this common for 911? This is my first one, so this is all new to me. It's like it is a foregn car or something....(just kidding)

sailchef · sailchef's Garage

The hot air going to the cabin is split between the defrost and the footwells by one of the three levers on your dash. Its either full defrost or full footwell, or , split between the two. you may have the levers set for the footwells so there wouldnt be much coming out on defrost.

you can also check to be sure your flapper boxes are working and that the hoses connecting the heat exchangers to the body are in place.

As you drive the car and your RPM's increase so will the heat to the cabin. There should be a large bellows type hose comming from an outlet on the side of the alternator fan up to the fan motor. The air from the alternator fan is forced up to the fan motor were it is pushed down thru the heat exchangers on into the cabin.

The Bently's book is a big help. Its the first manual I bought after purchasing my car. get one if you dont allready have it.

good luck.

RoninLB · 11-02-2008, 09:07 AM