Heater control valve

[string]

Hi guys I am going to order a new thermostat,temp sender from Euro CP's and I want to change the heater control valve at the same time when I drain the coolant as I only get cold air when the temp control is fully in the blue. I get full heat when the dial is in any other position.
I know there is either a plastic or ali control valve.Anybody know which one for a '89 G reg 320i M20.
Cheers

[Andy335Touring]

Have you checked that the cable from the heater switch to the matrix is still on ok ?

[string]

Yep,checked all the cables behind the panel when I changed the OBC,everything seems to be ok.(might be me )
When I turn the dial I can hear the valve opening and closing but it is literally right at the end of the dial when I turn it fully left.
But I will check again. It's a right pain even getting to the heater valve!
Cheers

[Brianmoooore]

That's when the electric valve is supposed to operate. It's not a variable valve controlling the amount of heat, it simply a on/off switch, ensuring that the air is totaly unheated when the temp control is sent to cold.
Your's sounds like a problem with the hot/cold air moixing flap, but not one I've ever come across.

[string]

Ah I love this place you learn somethin new every day! I hope it isn't the valve as they run around the Ԛ£70-80 mark. I think I'm gonna have to take some time going through all the heating system behind the dash to see where the problem lies.
Any other ideas gratefully recieved!
Thanks guys

[martinclan]

The heater valve should open when the heater control knob is at about 20% of its travel (from cold). If it does anything else than this then I would suspect the control rather than the valve.

[string]

Is there any real way of testing either the valve or the control?
I think the valve does open about 20% from cold but i can't be 100% certain.

[Brianmoooore]

The heater pipes should be cold when the valve is off, and hot when it's on.