that lever controls the amount of hot coolant frome the engine that goes
through the heater core ( and thus the heat output )

bottom of lever forward ( towards front bumper ) is 'on' ..or 'more.'
aft-wards closes the valve.
it's in the Owner's Manual.

*Always** keep it on at least half way so there is some coolant
circulation at all times.
( there won't be heat output unless the fan is on too of course )

not having coolant circulate through the core contributes to core
rot-out, which happens eventually anyway.

Scott
On 7/23/2014 11:53 AM, Eric Caron wrote:
> Hi folks,
>
>          under the back seat on the passenger side is a lever on the side of the heater.  It can be reached through a opening in the box.  I'm guessing this controls how much heat comes out the rear radiator.  Can someone confirm what this does and also what the position at the back of the bus is and the position toward the front?
>
> Eric Caron
> 85 GL Auto
>