Heater lever position / rubber flap position - which way?

[BHap]

Should the two rubber flaps underneath the main air inlet flap be open or closed when the heat is turned on ?  Is fresh air supposed to pass over the heater core to provide heat?  I've looked at the write up in the tech section and if air is supposed to go over the heater core when the heat is on, then the drawing is backwards.  When my left heat lever is all the way to the left, it raises the flap on the inside top of the heater core (the right red lever does the same on the other side) - shouldn't the valve be in the "open" position ?  My heater valve has been out before, but I'm pretty sure the cables to the flaps are original...  Any help is appreciated....

Bob Happe
Pittsburgh, Pa
1970 280SL

[jeffc280sl]

I hope you can read the instructions from the owners manual which are attached

[Kayvan]

Fresh air is suposed to flow over heater core (per Manual, slide to open fresh air vent).

Otherwise you rely on weak fan to supply air flow.

I though last winter my heater was weak; I had the fresh air closed (logic that cold air, would not help heat).

This year I opened it and heat is VERY HOT and whole vent housing under dash is warm to touch as well.

[JPMOSE]

The two flaps open for heat (controlled by the two lower levers on the dash).   The left lever also opens the water valve on the heater core.

As mentioned in the prior post, the main flap must also be open to allow fresh air flow into the two openings underneath.