Intermittant Air Con Failure

[20001200c]

Has anybody out there had their air con only deliver cold air, and then after a short period of time with the ignition off, when restarting it works fine?

This is not the best time of year here in the UK for this to happen!

 

[ant500sl]

I have exactly the same symptom on my 560. The bad news is in my case its down to a blown head gasket.

If a gasket blows into a water channel then when the engine is running exhaust gases will enter the cooling system and pressurise it. Gases will always rise to the highest part of the system which is the heater matrix, this prevents hot water passing through as normal - no heat.

If the engine is left for a few minutes these gases will disperse and water can pass through the matrix again - heat is back but is lost again when the system becomes pressurised after a short while.

Hopefully it will be something else but its worth letting a garage look at it.

Good luck