Hi Guys

Hope someone can help, I recently lost a small amount of coolant and the Audi garage diagnosed a tiny leak of a few drops from the rearof the cylinder head, their advice was try some K seal similar to radweld and if it doesnt stop it, then it's a head gasket.

I put in the K seal and the leak of a pint once every three months or so stopped straight away.

Anyway, two days ago the heater stopped working when the car was at idle, all I get is cold or cool air blowing until I rev the engine and then it gets warmer. The aircon works and the temp digital display reacts to changes.

The temperature gauge climbs straight to midway as normal and there is no collant loss, everything seems fine except the heater. I have checked the two heater pipes which go into the baulkhead and the top one is cold, but the bottom one is hot?

Anyone had this kind of problem, does it need flushing or could it be the heater valave and if so how big a job is this ? any advice gratefully received.