Heater Control Questions

[paslantnose]

Ok, i'm an idiot and i do not have an owners manual.
Can anyone explain the functions of the in-dash heater controls (1980 911sc) to me including the 2 levers between the seats???

[javadog]

Okay, in a nutshell...

Top lever on the dash controls input of fresh air to the car. Left is closed, right is open. About halfway to the right, you will start the operation of a booster fan. You'll see some marks indicating the fan speeds I, II, III. Later cars have two levers in the upper slot. The left one opens the air intake, the right one controls fan speed.

The middle lever controls where the fresh air goes. Left is to the windshield (top of dash) vents, right puts it out the floor ducts above the kick panel in front of the doors. Anywhere in between the two mixes the air between the two, output to each outlet is roughly proportional to where the lever is: closer to the left puts more out the dash vents, etc.

The two levers between the seats control the input of heated air to the cabin. Down is closed, up is fully open and anywhere in between is partially open. The left lever is for the driver's heat, the right works the passenger side. For any given lever position, the faster the engine speed, the more heat you will get, so you may be constantly adjusting these levers. If you drive alone, once the cabin reaches a comfortable temp, you may wish to close the left lever and open the right. It makes the changes in output with changes in engine speed less noticeable.

The bottom (red-tipped) lever on the dash controls where the heated air goes. It works in the same manner as the middle lever.

The A/C is seperate. The knob marked I, II, III, etc. turns the system on and controls fan speed and the other knob sets the output temperature by adjusting what temperature the evaporator reaches before the compressor cuts out. Both of these are best left all the way on, if you want any cool air.

All of these sytems work independently of one another.

Hope this helps,
JR

[msk1986911]

The only time I have air blowing from the vents is with the A/C (such as it is) on. Should warm spew out from the vents when the heat is on, or, does the warm air only come from the windshield vents and footwells? Also, my 86 911 does not have the levers mentioned in the preceding post, just a knob to regulate the temperature.

[imcarthur]

msk1986911

You have Autoheat. See AutoHeat

Ian

[javadog]

msk,

You should get a little heated air flow out of the two side vents on the dash. The center ones are for the A/C.

JR

[msk1986911]

Is the blower on the left side of the engine the only blower that provides heated air to the cabin?

[javadog]

No. On your car (a 1986 Carrera, if I recall correctly) the main engine fan supplies air that is boosted in output by the fan in the engine compartment and two fans behind the kickpanels in front of the doors.

JR

[Hetmann]

This is all theoretical of course.

[HarryD]

The truth is here.

[rnln]

Sorry, can I jump in?
I want max hot air comes in, mostly for the cabin when the car is idle. I usually pull the levers all the way up and that's it. If I turn on the dash fans, all the fans blow out is cool air.
What is the setting for hotest air regarding this?
Thanks.