Damn, i'm posting a lot, but this is a heater question...

We're getting massive amounts of rain down here, so I need to get this straight. Supposedly you get max defrost with the top control left and the two others right.
But, I don't get any air flow with this configuration. In fact, I don't get any air flow at all unless the fan is on, and if it's not on, the window fogs.
My question is, the heater blower...what, where is it? I'm thinking it's the black one in the engine bay....and it should be on when...when what? There are also the two controls between the seats.
This is driving me nuts: either freeze and see, or be cuddly and warm and drive blindly.

Wow, it sounds like you're really serious about figuring this out? I don't think anyone really knows how those controls work including the engineers who masterminded that system. I certainly admit I don't have a clue, I usually just slide them around and pull the levers willy-nilly until I get some effects that please me.

Kurt, the two between the seats are for heat and turn the heater blower fan on. (Yes the black one in the engine compartment). For max defrost, pull the two between the seats all the way up and the red one on the dash all the way to the right. I sometimes turn on the fresh air blower, (Top lever) with the middle lever to the right as well, for defogging briefly. Best De-ice is with the top two full left and bottom one full right. And of course the two between the seats full up.

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Tyson Schmidt
72 911 Cabriolet

Kurt,

Since I've been messing with mine lately, I've figured this out a bit.
There is a switch that is closed when the levers between the seats are pulled up. This switches on the fan (or is supposed to) in the engine compartment, assuming the car is on. You can jumper the wires here to check if the problem is in the switch. This fan has a relay and a fuse in the small cluter of stuff on the drivers side of the engine compartment. In searching prev. posts, alot of people seem to have this motor not work b/c the fuse contacts get corroded. Of course, this was not my problem, its never that simple. I don't seem to be getting power to the switch at the heater levers between the seats, and hence, not to the fan motor. On top of that, when I was messing with this all, one of the cables to the levers broke.

I seem to get a little heat thru the defrosters with the fan off (2 lower levers to the right). With the fan on, it blows cold air even with the levers up. This defrosts ok, but is pretty cold on the face. Maybe if I could get the fan to work, there would be enough hot air to the front so that the fan in the luggage compartment could run without blowing cold only.

I guess there is a full moon here.

Anyway, hope that helps a little.

Nick.

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Nick Shumaker
1982 911SC Coupe

O.K. Try this-top lever all the way left
middle lever all the way left
lower(red) lever all the way to the RIGHT. Now you shouldn't have any air flow at this point. Lift up the 2 levers between the seats and the air should start flowing, warm, and in proportion with how high you raise the levers. Now you may adjust your auto or manual dial between thes levers to your desired comfort . LOL! This dial is worthless in my opinion! When you start to heat yourself up like last night's dinner, just turn on the a/c to low speed and rotate the temp knob(left knob) counter-clockwise fully. Don't forget to turn the rear defroster on by the pull switch on the dash if it's fogging the rear window.

Right, thanks a lot. I will check the fuses back there, and if that comes up empty, I'll check a direct connect (12v) I assume to the blower and see what happens.

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Kurt B
1984 911 Carrera Cabriolet
75 914 1.8

I find that the engine fan has very little effect on the demisters - is this normal?

Kurt,
The top lever on the dash also needs to be all the way to the right. You are not getting any outside air if the top lever is all the way left. If you are trying to defog you will need to circulate outside air. The middle lever directs the outside air to the floor (left) or to the defroster vents (right), the bottom lever adds hot air when it is right and the heat lever between the seats is on all the way. I hope this helps. I have replace all the fans, etc on my 1984, so if you have any other questions I may be able to help.
Paul

You say you have two levers, so I assume you have the manual setup (no climate control). When you pull either lever up, a switch contact is made and current goes to the heater blower motor in the left-side of engine bay. Often, the switch will break or the user will not push the levers all the way down, resulting in a continuous-running heater blower motor and eventual failure or overload (note wires and block to blower for melted state).

To receive the entire amount of hot air you deserve, you need to ensure that, when you pull up on the levers FULLY, the heater boxes CLOSE completely. This is almost never the case as the steel wires to the heater boxes stretch and you will find that even with the levers fully up, some amount of hot air still escapes the boxes and thus does not run to the cabin proper.

So, jack up the car, pull the levers up completely, and get under your car to note if there is ANY opening in the heater box flap. If so, loosen lock nut/screw at the heater box, rotate the flap FULLY closed, then tighten the nut/bolt. Have a care; they break! Some Liquid Wrench is in order here. Also, while you are under the car, operate the heater blower motor and feel for ANY air that is "leaking" from the heater hoses, ducts, and whatnot. Any air getting out here is NOT getting to your cabin.

Also, what I did when I found a "bad" blower motor was to take the two yellow wires that go to the heater switch in front of your heater levers and attach them to a toggle switch instead. Now, the heater blower motor only goes on when I flip this switch. Doing this lets me use the motor to force air (levers up, of course), turn the motor off and use the car engine's natural blowing force from the rear fan (again, levers up), or shut the levers off for no heat at all.

John

For MAX HEAT to the defroster (to melt ice).
Upper lever full left (this closes off outside air), and fan off. Middle lever full left, and bottom lever full right. This will direct all of the hot air from the heat exchangers to the windshield, while blocking any outside air. This is good only for melting ice. If you want to de-fog, put all of the levers fully right to get the most air flow to the windshield. ALso open the center air vent, and turn on the A/C if you have it.

I've been getting this to work OK, at temps down to -10F without a working aux heater blower. However, keeping the side windows fog or frost free, has been spotty at best.

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Bill Krause
'79 911SC Euro

Sorry to do this: I keep a small towel handy in the door pocket too .
John

Rain X Aint-Fog works wonders my friend. I put it on the bathroom mirror if that tells you how well it works...

I think I'm going to try that Rain-X stuff. I keep an ice-scrapper in my door pocket, and I use it on the INSIDE of the side windows.

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Bill Krause
'79 911SC Euro

How did that happen?

[This message has been edited by wckrause (edited 01-11-2001).]