<VV> '65 Corvair heater "FAN" selector has 4 settings?

[Charlie]

Still working on getting some heat in my 1965 Monza 110 4-speed convertible:

The Corvair heater "FAN" selector seems to have 4 "detents" for different
settings.

Assuming all the way up is "off," what does each "step" down accomplish?

I just refurbished the fan blower motor, removing a few spider nests and
what may have been the grisly end for a mouse.

The blower motor works (nice and quiet after greasing the shaft and removing
the grunge) 

Connecting it directly to battery and ground, it's OK, but not from the
controls on the dash.  

The resistor has 12V where it should but it seems not to get back to the
connector to the motor (back over the rear axle.)

I suspect the connector behind the dash that feeds the instrument lamps
(which do not light, but the "ALT" and "TEMP/PRESS" lights do work)

I'm trying to figure out the switch behind the heater controls while I'm at
it, hence the questions that may be a bit tangential, but I'm curious, and
it may be part of the problem?

Thanks!

Charlie