Tony_J

Thanks for the tip, I'll have a look over the xmas break. Glad you finally found the solution to your cars problem, I suspect mine is suffering from same thing. Cheers and Merry Christmas

Don't know what's going on but I have found that driving in town can be made warmer by keeping in a lower gear, so the revs stay up around 2k at least. I'm sure it's doing nothing for fuel consumption but given the minus 8 degree temperature on my way to work this morning I can live with it. I thought it was a water pump issue because the heat only comes through at higher revs but seeing that replacing it has done nothing for others I'm not so sure. Are there any filters in the system that could be clogged up?

I think I have the same problem on my 2002 Octavia Elegance TDI. The heater gets fairly hot when I am at a constant speed at decent revs, on the motorway for example. However when the car is stationary or stopping & starting the heater goes back to blowing otu cold air. This happens with or without the A/C engaged. I doubt it's the mixer motor unless there's a chance it's opening and closing at random. I would have thought it's the water circulation, maybe an airlock. I'll have a search on how to bleed the system (unless someone can link me straight to it!) p.s. Please don't reply "plug it into the diag machine." I'm sure this leads straight to the problem in 99% of cases but I don't have one and when I run out of DIY options I'll pay someone to have a look. Right now I'm skintypoos so I'd prefer to keep what money I have!