Round heater dial should create BLAST of air from heater blowers. (If not, read this)

[sugarwood]

As winter approaches, I am posting this for a friend who is also a 911 beginner. If something is already broken when you get it, you might not realize it's broken. When the footwell blowers are dead, you will still get a weak trickle of heat from the engine blower motor. You might think this is just how it works. If there is ONLY a weak trickle of air coming from your vents, and your red round 0-3 dial doesn't seem to do anything, then your footwell blowers are stuck. When it's working right, the 911 heat is like a hair dryer. TONS of air blowing. And loud!

Here is how to work the heater controls
Heater controls 101. Plus, I'm not sure windshield vent is actually working.

First, remove the carpets footwell heater blower panel. There are 2 screws up front, and one on the side.

Here is what is behind the covers....
You need to remove the motor. This is the slightly tricky part.
Once you loosen the 2 hoses directly attached to the motor tube, you need to angle the motor so it lifts out.
As you can see, the blower is blocked by the black tube directly above it. No need to remove the black tube above it.
You do need to angle the motor to the side. The base connector is rubber, and allows lateral play. You might even tilt it, and remove the base part first.
Try to look at how the motor is installed. Take a photo, since you’ll need to align it the same way when reinstalling.


The fuse socket is right there also. Your fuse will be blown. 10a ATC fuse. You’ll need 1 for both sides.
Might as well order a handful, in case they get stuck and blow again.
http://www.amazon.com/ATD-Tools-364-120-Piece-Assortment/dp/B000M61JFC/ref=sr_1_3?s=automotive&ie=UTF8&qid=1414350405&sr=1-3#productDetails

On the right side, both air tubes are connected to the yellow plastic.
Loosen the clamps, but they may not slide off as expected.
You need to angle the base of the motor so you can drop the motor down, as opposed to lift the tubes upwards.


This white clip just pulls off.
I never knew how to deal with that paper clip part.
Turns out you don’t remove the paper clip.
You just yank the white housing right off.


Once you have the motor out, remove the top screw, and slide the top upwards.


Top is now off. While you're here, drop of oil on the spindle contact area.


Next pry off the 4 clips holding on the base. (Use pick tool)


See the squirrel cage? That’s the fan that gets stuck.
Just turn the thing to get it unstuck.


If you have test leads hooked to the battery, you can try powering the motor electrical prongs, and it should now spin.
To test the motor in the car, first replace your blown 10a fuses. Then just reconnect the motor to the white power plug (leave everything else disconnected),
and pull the heater level switch up, and it should spin. Also, try all 3 settings on the round heater dial. THAT's how they work! Low, med, high!

If the cage still feels tight, pry up the squirrel cage a bit, to create a gap.
If you try to pry up from just one spot, you might crack the squirrel cage.
I used 3 trim pry tools and jammed them all in to spread out the pressure.
See how I left a little gap?


The hardest part, by far, was lining up that bottom screw in the carpet kick panel.
I had to use a piece of coat hanger as a guide through the panel, the carpet, and the screw hole.

Again, here is how to work the heater controls
Heater controls 101. Plus, I'm not sure windshield vent is actually working.

[DaleR129]

My footwell fans run for about 20 seconds after I turn the rotary switch between the seats and then shut off. I've taken them out, lubed them up and run them on the bench with a 12V power supply and they seem to run fine. Are there any thermal switches in this circuit? Any other ideas about what is causing the fans to shut off?

[Farrell]

i have a 1982 SC. i don't have this round heater dial. do all of our SC's have one?

this car is freezing to drive when its 40 and under. i don't feel a lick of heat in this car with the heater levers up.

[Farrell]

i also don't have two levers on top of my controls. are there supposed to be two?

[pavegeno]

The heater in the 911 is an oven! Been driving in the low 30s here in Stuttgart lately and one of my favorite things about this car is about 30 seconds after starting up and turning the heat on, it's already coming out warm. I pull both levers between the seats all the way up (this turns on the engine compartment heater fan) and turn the footwell blowers to 3. (Never noticed a real change with speed 1. Speed 2 is noticeable, and speed 3 is amazing). The red defrost lever goes all the way right for 100% defrost heat and 0% foot heat, and the upper black levers go full left (2 of them in the upper level on a Carrera - one turns off the vent fan and the other prevents outside air from coming in for the vent function). The middle black lever is meaningless in the heater mode. Within a minute the windshield is clear and I lower the red levers to about 20% open and turn the footwell blowers off. I move the lower red lever left about 25 % of the way so I have 75% of the hot air going up to the defrost vents and 25% going down to my feet. After driving 10 minutes or so, the car is very toasty. Amazing!

When I first bought the car the engine fan didn't work. Because the engine fan didn't work, the footwells didn't come on because they are linked to the engine compartment fan. As long as the car was moving, I got heat and it was pretty good. Once I realized the engine heater fan was broke, I fixed it. As soon as that worked, the footwell blowers came alive.

Good luck...a fully functioning heater is amazing in these cars. Tackled the A/c Next with a Griffiths install and now my car is drivable from sub-freezing to 100+. Worth every penny!

[pavegeno]

The footwell blowers should go off as soon as the levers are down as that turns off the engine compartment fan which is where the footwells get their power from.

There are times if the engine is hot that the engine heater fan will run after shutdown (on my 88) to cool the engine. Only had that happen a few times when my onboard oil cooler was dying.

[Farrell]

dang, i have both levers up and the levers set the way you are saying and i get ZERO heat. maybe a TRINKLE through the dash vents but that is it. i have to drive with gloves, a sock hat, two jackets and extra socks to keep my toes from freezing.

i wonder if my fans are broken?

[pavegeno]

when you raise the levers to you hear the fan in the engine compartment fan come on? If you have the engine off and the key to "run" you can hear the engine compartment fan when you raise the red levers. If not, check the fuse (think it's in the engine compartment, but check your manual) and then check your engine compartment fan as the next step to see if it is getting power. Lots of posts on here on how to check it

[frannyB]

My fan motor squeal every time they start up cold. I've had them out and completely re-greased multiple times, but I think the bushings are just shot. I just ordered two new motors (the AC blower replacement) for $111 shipped from ********AZ. I'll swap them out and I should be good to go. They are physically the same except for the wiring - easy fix though...

I did clean the communitators really well. The brush graphite had completely bridged several of the contacts on the armature . That helped a lot as they would spit fire at full throttle - very exciting!

I'm just done messing around with these crappy old motors so I'm replacing them.

If you don't have heat with the levers up, check underneath to see if the heater box flappers are connected to the other end. The cable will stretch and mine barely opened at all when the levers were all the way up. I adjusted them and even with the old motors, it will heat you out of the car fast on any day above zero. Much below that and I drive something else that isn't air cooled. The de-frost rotary know will make them really go!

My car is an '86 3.2...

Franny

[wrxnofx]

Originally Posted by Farrell

dang, i have both levers up and the levers set the way you are saying and i get ZERO heat. maybe a TRINKLE through the dash vents but that is it. i have to drive with gloves, a sock hat, two jackets and extra socks to keep my toes from freezing.

i wonder if my fans are broken?

I'm pretty sure the footwell blowers didn't show up until 1984. I think your '82 only has the engine compartment blower. I would guess your engine compartment blower is cashed. Either that or the relay is shot.

It's easy to remove the engine compartment blower. Hook it up to a 9 Volt battery. That is enough to see if it works or not. Heck, just unplug it and stick a 9 volt battery on the 2 terminals. If the blower works this way, then the problem is most likely your blower relay.

[86 ssinit]

Even with the blower motor broken with the car moving you should get heat. Farrell Do you have heat exchangers around you exhaust pipes??

[Tremelune]

The heat in these cars is nearly immediate, and can sweat you out of the cabin well below freezing. It's time to check your heating system out. It's completely weird, and different with just about every model. A search on this forum for "heat" will show you more than you ever wanted to know.

There is a very good chance that your issue is electrical, as the footwell blowers and engine blower work in tandem in a strange way through a strange relay and temp sensor...Fun stuff.

[wwest]

Originally Posted by DaleR129

My footwell fans run for about 20 seconds after I turn the rotary switch between the seats and then shut off. I've taken them out, lubed them up and run them on the bench with a 12V power supply and they seem to run fine. Are there any thermal switches in this circuit? Any other ideas about what is causing the fans to shut off?

The engine compartment cabin heater blower must be running and drawing a specific level, or more, of current flow or the footwell blowers will be disabled.

Reed relay in the cabin heat control module blower motor current flow.

[jlex]

My '85 Carrera had no heat when I first bought it in 2000. Would turn the rotary dial and could hear the servo motor running just below the dial, but no heat. Took the dial and housing off to find the rod connecting the servo motor to the control was broken. Fixed w/ a stiff wire. These heaters do get really hot.

[Nostril Cheese]

Sorry to say that the SC doesnt have the footwell blowers. They can be added though and do make a big difference.


If you have no heat, check that the fan in the engine compartment is blowing. Turn the car on (dont start the engine) and pull the levers up. You should hear the fan kick on. If it does, check the hoses to and from the fan for cracks. If those are sound, jack the car up and check the hoses from the heat exchangers to the heater control boxes. These typically tear due to age. Also check that the cables to the control boxes actually work. These tend to rust and the flaps inside get stuck.