Heater control knob issue

[Smudgemanuk]

Just to confirm this is the knob I am talking about.

The heating in my z works fantastically but only when this knob is turned to full hot. As soon as I slightly move it off from full hot the air becomes pretty much outside temperature.

Maybe this is what they are all like?
Or is there a common fix to this issue?

Thanks
Chris

 

[Pond]

There is a microswitch attached to the rear which opens and closes a valve to let coolant flow around the heater matrix. The switxh is made by a little plastic tag on the rear of the temp dial and should open the valve just warm of cold. The heat is then blended by the flaps.

Your switch may have moved, or someone has put the dial back on incorrectly. You will need to get the heater control panel off to check.