Heater Valve and Temperature Control Wiring

[sublimation]

Hello,

I was hoping someone could help me diagnose the issue that I am having with my HVAC where I have full heat all the time.

My heater valve is receiving no power as confirmed by a multimeter. It is to my understanding that when the heater valve receives no voltage it is fully open - hence my problem.

After checking for voltage at the valve, I then pulled the dash apart and found no power at the temperature dial/ rheostat as well. All my underhood fuses and relays are good.

Has anyone had a similar experience and/or can advice on what to troubleshoot next? I have looked in the bentley and wedophones wiring manuals for the correct diagram to no avail. Car is a '91 318is.

Thanks.

[reelizmpro]

You are correct the valve is normally open. From the ETM, it blocks water to the core when energized. It gets power from a 2 amp inline fuse on the HVAC unit above the valve and from a water cut off switch that opens when the temp dial is rotated more than 20 degrees from the coldest setting. The whole thing is powered by Fuse 20, 30 Amp fuse. Hot in Run only from unloader relay K7.

The diagrams should be in back of the Bentley.

[spdracrm3]

the water shutoff valve is not your problem , it is only closed for max AC performance. the temp is controlled by an air mix flap and you should be able to control the temp from full hot to almost cold without activating the water valve at the lower 20% of dial. you need to find out why your airmix isnt controlling temp ,water valve is open at anything above the lower 20% of dial so heater core will be getting full coolant flow (its not duty cycled either on/off) therfore temp has to be controlled by the temp/airmix blend flap which is cable controlled


from factory manual