My 450 city coupe +passion (1999) has decided to beep at me because it is overheating. I turned on the interior heater and fan to full to try and reduce the coolant temperature until I could get to a safe place to pull off the road. Second problem, no hot air from the heating system! (Obviously an air lock somewhere in the system). I managed to stop on a garage forecourt, so was able to buy a litre of ready mixed antifreeze. When the temperature would allow, poured the anti freeze in - lots of bubbles and overflowing of the header tank. More water as required.
Finally got hot air from the heating system, but very soon after driving off, overheating again! Back on the garage forecourt, more water into the system.
Getting intermittent hot air from the heating system. Eventually, managed to get stable hot air from the heating system (it seems very hot). Managed to drive to work with no further overheating issues.
Drove home this evening with no overheating issues. I did have the interior heating on full blast!
Question: At no point during the overheating / beeping did I hear the sound of the front fan.
Question: Can you turn the front fan on using Star C3 diagnostics? If so where do I find it.
Question: Where is the sensor which should turn it on? Is it the normal temperature sensor on the thermostat - in which case that's working as the temperature gauge "blobs" went all the way up and that should have turned the fan on.
Question: Where is the most likely place for a leak? It must have one to develop an air lock out of the blue.
Any help appreciated.
John