Hi my name is***** a car technician and I’ll help with your question.
When you say the heater is not working, is the fan not working or is there simply no hot air?
no hot air
any joy yet
Ok, This is a common problem, but i will start with some basic checksFirstly, have you checked the engine coolant level?
coolant should be fine,just had a new cam belt
Ok, is this petrol or diesel?
There are two common problems on these, firstly is the thermostat, this is more apparent on the diesels as they take longer to warm up. If the thermostat is stuck open the engine coolant will never reach a suitable temp to supply warmth to the cabin. This is simply diagnosed by ensuring the temperature gauge reaches half way and stays there when driving. Providing this is OK the most common cause of this is the diversion valve which diverts the hot coolant into the cabin heater when the temp is set on the control panel. These often fail and stick on cold.
I know access is not great on these but a simple check is to run the engine up to full temp and carefully check the two small coolant pipes going into the bulkhead from the engine bay, you will find the pipes are cold if the valve is stuck, they should get hot as soon as the heater is set to the hot position. Unfortunately there is not much that can be done as a quick fix other than replacing this valve ( Around £20 )
the temperature gauge is not going above 80 celcius
Providing it reaches 80 and stays there that would be considered normal operating temp so i think that can rule out a thermostat problem
ok,will fit new diversion valve
If you need further help with this problem please feel free to ask. I'm always here to help! Otherwise good luck with the repair. thanks, Ross.