Interior C8 Heater Doesn't Work When Car Is Stationary?

[Guest Panddda]

Our 2004 2.0 petrol C8 has developed a bit of a bizarre fault: the interior heating works fine when the car is moving, but as soon as we stop (and leave engine running) it starts to blow out cold air!

 

It's not because the engine is cold either - just completed a 60 mile trip in cold weather and after the initial couple of minutes on the road it warmed up fine to maintain the 22 degrees shown on the panel. However an hour later stopped and I waited in the car with the engine running for 5 mins while hubby popped into a shop and within a couple of minutes it was blowing cold air at me (outside temp I reckon, not air-con chilled). On recommencing the journey, it warmed up again.

 

Any ideas?

Thanks for any help anyone can offer!

Claire

[paul.h]

This must be either the air stops blowing through the heater matrix or the hot coolant stops going through the heater matrix. For the latter see if the hoses in to the bulkhead to the heater cool down and also check if it improves if the engine is revved whilst stationary - if so there may be an air lock or possibly a problem with the water pump. For the first possibility a ducting flap must be switching to the cold position. I have not seen a C8 so can not suggest much more.

[Guest Panddda]

Checked it tonight, and it does seem to warm up a bit when revved. Hubby going to have a look at hoses and see if that's the problem.

 

Thanks for the advice.