I have a 52 1.8 lx petrol mondeo and recently the interior heater control has started to give problems. If I turn the heater from cold to hot only cold air will continue to blow from the vents. Sometimes turning the heater back and forth will get it to work and sometimes it will start to emit hot air several minutes later.

Is this likely to be a problem with the heater control knob, or heater valve or something else. Im not familiar with this electronic system, give me the old heater cables anyday.

Any advise on where to look to solve this and any tests I can do would be great.

Thank, John