1976 911S Heater/Fan Knobs

[Swordfish II]

Can anybody scan the heater/fan/vent knob section of the owners manual? The labels wore off before I got the car and it would be nice to know what does what.

[911ish]

Hope this helps. Disclaimer: this is a photo that I saved off this board long ago.

[Swordfish II]

Thanks, that does help a lot! Wish there was a scan of the next page for the bottom lever

[93nav]

Pic below is from a pdf scan of a 1977 manual. There is/was a very good thread on these controls I had read a few months ago. Not sure how you would find it though.

[frankc]

Originally Posted by Swordfish II

Thanks, that does help a lot! Wish there was a scan of the next page for the bottom lever

Actually, the operation of the bottom (red) lever is described in the last paragraph of that page. The text listed in the manual appears to be incorrect and should state:

"When the manifold heater is turned on (levers on floor pulled up), the bottom lever regulates the flow of hot air coming from the heat exchangers in the same way as the regulation of fresh air flow."

Regarding the '77 manual page - the top lever control for '77 is different due to the introduction of the center dash vent in that year. The middle and bottom levers are the same.

I created a diagram in the link below of how the air flows through the HVAC system for '77 & later cars which you may find helpful to visualize what is actually happening when you move the levers.

Retrofitting non-A/C ventilation ducts

[Jrboulder]

[Swordfish II]

Thanks guys. So am I correct in stating with the lower red lever in the left position all heating ducts are closed, In the center position heating is channeled to both lower and upper vents, in the full right position heat is channeled to the upper vents only?

All this is independent of the other two levers.

[frankc]

Originally Posted by Swordfish II

So am I correct in stating with the lower red lever in the left position all heating ducts are closed, In the center position heating is channeled to both lower and upper vents, in the full right position heat is channeled to the upper vents only?

No, the lever(s) on the floor control the amount of warm air entering the system (they operate the "flapper valves" at the engine heat exchangers). The bottom red lever on the dash only controls the distribution of that warm air: bottom -> top.

The same is true for the middle dash lever; it only controls the distribution of fresh air that has entered the system (bottom -> top). The top dash lever controls the amount of fresh air entering the system from the cowl intake (similar to the levers on the floor for warm air).

The introduction of the center dash vent for '77 added yet another level of complexity (if no A/C) which I won't get into here.

Originally Posted by Swordfish II

All this is independent of the other two levers.

Yes, but you may want to blend the fresh and warm air to obtain the desired temperature.

I know this may sound a bit confusing at first, but once you realize how it works, it is quite functional.