E46 2003 320d Heater Blower issue

[aust240378]

Hi all,

I have a 2003 E46 320d which has started showing a problem with the Heater Blower which It seems to be the opposite problem to any other posts I can find on the subject.

The Symptoms of the problem are as follows. With the climate control set a 21 on auto I find that on every commute (45 miles) at least once during the journey the vents will start blasting out full hot air (usually when braking or in stop start traffic)
If I turn down the heater to 16 it blows the hot air still but at full power but if I turn it up to 32 and back down to 21 it fixes the issue! This is what I have checked so far:-

1. OBC displays the car running at at constant 83 which is on the low side but unrelated and it never overheats.
2. Fan operation is fine no intermittent speed changes or not strange behaviour manually operating the man speed it always works consistently ruling out the Final Stage Resistor (Hedgehog)
3. I have a C110 scanner and scanning showed an error relating to the re-circulation which I don't normally have switched on.
4. Temp sensor is clean behind the heater control I used some compressed air on it.

I thought from reading other people only getting cold air it may be the heater control valve, but if it was I would assume that it would stay stuck and me fixing it by changing it to 32 and back down to 16 again wouldn't work? The same with the blend door?

I think my first step will be to take the heater control valve out and see if the pin inside is getting stuck at certain points i.e full heat request would move it all the way out to allow flow and full cold request would push it all the way in to block it flow, maybe a request of a mild blend of heat and cool is causing it to stick?

Failing that I'll see if I can get hold of a cheap climate control panel replacement as this may be sending a false command to the system ordering maximum heat and try swapping it.

Any input or next steps appreciated.

Thanks!