In car heating cuts on and off

[daveR@2lk]

Hi there,

I've got a 1990 16v golf and the in car heating is being a bit strange. It heats up OK but then can just go to cold air at any time with no warning. The fan is still pushing the air out at the same flow but the air  is cold. It can stay like that for a whole journey or come back on if I'm lucky. I would like to get this sorted before the real cold weather kicks in. Any ideas on what this may be??

Cheers

[sKrEwBaLL]

Theres been tons of posts on this recently.  Have a read through them.

[golfvr6]

The main problem seems to be the bypass valve, as mentioned in lots of other posts.