Q: My heater is always cold for some unknown reason. The centre knob on the heater control board does nothing at all. Is the heater controlled by a water flow valve or a flap that diverts the airflow over/through the matrix. Any help will be apreciated its a phase one 2 litre engined petrol.
A: Probabilities; 1. no thermostat or it's stuck wide open... 2. clogged or pinched pipes.. flow or return pipes. 3. clogged heater core and or low coolant levels.. [air trapped in heater core] 4. broken controls like the cables, switches, or flaps that operate the system. Does this help any?