This video explains how to replace the heater control valve on BMW 3 series built between the years of 1991 and 1999 if equipped with the valve that has the 3 heater hoses located on the same side, two upper outlets and one lower inlet.
https://www.youtube.com/watch?v=SD9FBtSTLv4

How To: E36 heater control valve replacement
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Home / BMW E36 328i Sedan / Repair Manuals and Technical Data / 64 Heating and air conditioning /Search documents:64 00 Note, overview components climate control >
64 12 Auxiliary heating with control element >
64 50 Air conditioning, check >
64 51 Heating and air-conditioning unit (evaporator), shift elements >
64 53 Condenser and dryer with lines >
Tightening Torques (COM) 64 operating fluid overview
Repair Instructions (REP) Information on using cleaning agent/paints (personal protection equipment)
Operating fluids (SBS) Main group 64
Service Information (SIT) Heater not providing enough heat at idle speed E36 petrol-engined
Applies to: NOT USA
Applies to: NOT USA
Service Information (SIT) Musty odour from heating and air conditioning system, evaporator cleaning
Applies to: NOT USA
Service Information (SIT) Operating noise from the air-conditioning (a/c) compressor E36 with a/c unit
Applies to: NOT USA
Service Information (SIT) Reduced air output E36 with IHKR
Applies to: NOT USA
Technical Data (TED) A/C system, refrigerant amounts