Vw Golf R heater blowing cold

[Maki65]

Our Golf R 14 plate has started to blow cold air in a morning for 4 or 5 miles before performing as it should then on. The heater has always been quick to be effective, but never this long. I have called my local specialist who is 99% certain it is a blocked matrix, due to potential silca from the bag in the expansion tank (mine does not have one!) or casting sand in the system that is there from new. Apparently the latter is fairly common.



I am a little puzzeled because if the matrix is blocked why would it start working normally after 4 or 5 miles? I have had a blocked matrix on my TR7 V8 before now and that did not get warm at all ( a proper pig to change that one!).



Has anyone had a similar experience? I have booked the car in as he will do a check before changing the matrix and back flushing the system. That said he cannot fit it in until the middle of March which makes me a little uncomfortable driving the car, which should be fine for short journeys. any thoughts?

[Dr G]

If it's normal after a distance I'd look more closely at thermostat and mixer flaps than the matrix.

[Maki65]

Thank you for the reply. Yes I will, I do suspect the heater control valve though. I have the car booked in at a VW specialist in a few weeks.

Thanks again