2009 intermittant heating problems
I drive a 2009 Focus SEL and am having intermittant heating problems.
About once a week I don't get much heat through the car even though the temperature gauge is in the middle. It doesn't blow cold air but it's not as warm as it can be and doesn't seem to be related to outside temperature. The car is higher mileage so I changed the coolant and the thermostat. The system is bled properly.
There are no fault codes in any of the modules and the blend door is working properly each time I check it. The only possible cause I can find is in the heating module. It shows 'Engine Coolant Temp Gauge (degreesC) 500'. I don't know what this means. I know there is a cylinder head temperature sensor and it is reading correctly but I can't find a coolant temperature sensor which I would expect to find in the engine block. Does this car have one?
I would appreciate any help to clear this up and any information on this cooling system in general.