Vito interier heater help needed

[mikeLmedic]

Hi - just bought a 2002 Vito Traveliner and the temp control knob for the interier heater just spins round - removed the unit to find attachemnts for a cable on the back but I cant find a loose cable anywhere!

There are two cable on the central knob controling which vent the air is sent too - that one is fine.

Any idea what colour or the routing of this cable should be?

Cheers

Mike