1948-7519 Limousine heater question

[Hilarius]

Hi all.
I just bought a 1948 75 limo which has been standing for a long time.
It has underseat heaters and a vent motor out front, and I cannot, for the hell of it, find the knob or whatever it is that actuates the heater.
On the 1939 and 1940 models that I own there are the knobs for low and high speed on the left side of the steering column, but where are they on the 48 model??
A picture would be greatly appreciated or a description of the place where to find it.
Thanks.

[Richardonly]

If this pic comes out, the temp is one lever and defrost is another.  The motors (rebuilt) are so quiet and move air so little that I have to look at the volt gauge to make sure they are on.

Full upright position on both, shuts down the heat.

The car is a 1948 60S, which may be different from your setup.

[Hilarius]

Richard,
thank you very much for the picture. The setup is the same on my car, so I am sure what you write applies.
I cannot judge by the ammeter as it doesn't work yet, but I'll watch the underseat heater ventilators for movement.
Again, this was great help!
May I ask still another question: what is the knob for on the left side of the steering column to the right and at right angles to the light switch??
Sorry to have to ask these questions, but I have so far been unable to find an operators manual for the 48.