AU II air vent problem

[Gavin]

Hi Everyone, need some help, got an AU II sedan ( air vents set to face vent setting)when i select any temperature on the temperature dial above coldest the air is directed away from face vents and onto the demister, no air at all comes from the face vent. when i select the the coldest setting the air flow is split between the face vents and the demister vent.
Have a good day all. Gav

[Steve_T]

According to my car it should actually be the second click up from coldest on the temp. dial where your problem kicks in as thats where it operates a vacuum valve - is this right.

If so, it must be some sorta vacuum problem (all the vent position controls are vacuum operated and the hot water tap for heater is vacuum operated from the temp. switch too). Sounds like when the hot water tap gets turned on you have maybe a vacuum loss or similar problem in some line which is causing the vents to alter.

Can anyone here remember the default position the vents go to when there is no vacuum - I thought it was face but maybe it's windscreen - would help diagnose the prob.?

[Gavin]

Thanks Steve_T, yes you are on the money it is the second click, i will have a look at the heater valve. CheersGav

[Moran]

When vacuum loss occurs it defaults to screen

[Gavin]

can anyone help me with a circiut diagram for the air vent system, and how do i get access to the blocks on the back of the air controls. Thanks Gav

[Steve_T]

So it sounds like when you're opening the heater tap, it's loosing vacuum - when this happens, take notice of the motor - you may hear it run slightly different and if you listen you should hear a constant hiss from behind the temp control, yeah?

Could be the actual vacuum valve on the back of the temp control dial. Could also be the line between that valve and the heater tap - have a look at the connection diaphraghm on the tap to see if it's ok and maybe see if the tap actually moves at all when you change the control. If you need to get to the valve behind the temp control, you'll need to pull the radio out and then can't remember if you need to pull the whole centre panel out - think you do though as there's screws on the back of the controls holding 'em to the pannel. Unsure about diagram for air controls, but for heater tap it's just the one line from tap to valve and then from valve to t-piece off of another line from the vent selector.