I don't recall having these knobs in other ambulances. They are not labeled. Maybe one for fan? I have had the color coded lights and buttons before (in Superiors) telling the driver how fast to go. Thanks as usual, in advance!!!!
Without going out to my car, I believe that the black one is the roof ventilator fan, and the other is the dimmer for the light over the cot. I can check in the morning, too tired to walk down the stairs and out to the car. Old age.
Or heater blower and as blower. The one with the pointer is normaly a blower switch. But with out seeing how they work you cant tell. Most ambulances have a control switch for heater ac and lights by the attendent seat.
In my 54XL Patient's Compartment, I had 1 mystery knob that was a dimmer switch for the cot light ( I still do not know if it was factory or aftermarket) and one mystery switch that would turn on/off a music radio speaker connected to the front music radio.
I still have one mystery switch in the driver's main control panel that I hope to figure out when the car gets back from the body shop.
Let's not forget that quite often the ambulance operators would customize stuff to fit their needs, so it is not because it is there that it was factory.
I have no cot light, I have no fan. One switch, which does nothing, is marked off, low, med, high. The other turns on the 3 dome lights, and a small light by the attendants seat. The 3 dome lights are the same fixture as over the driver's head. Not a spot light by any means.