Heater valve or flapper failure?

I have a BMW 3 series e36, my problem is the heating of the cabin, the driver's side works normally on the passenger side air is always fresh. when I turn the air conditioning and cold I select to work well on both sides, only on heating is not.
I think it is the heater valve. I ask for your help. much obliged



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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW Heater Valve Cleaning/Flushing

[Wayne 962]

I think you're probably correct. If you're not getting any heat at all, then it is probably your heater valve that is not functioning properly. If you get heat on one side, but not the other side, then the problem may be with your control unit, or it may with the flapper valves located inside the heating ducts, behind the dash. I would probably investigate the heater valve first, as that is typically what fails initially.

- Wayne