Bobcat heater control

[laurencen]

looking for some info how the heat valve works on my Toolcat which is the same as my S590 and many other machines, to control the heat there is a rotary potentiometer, this connects to the valve which changes the water flow thro the heater core, on my machine the valve is open and the potentiometer does nothing, anyone know how this valve works with the switch? where does one start to check it? as always the valve is buried under the seat housing, switch in the dash

thanks