1996 BMW 740 IL - Water Valve

[Chrisannagenna]

I figured I'd start a fresh thread, since my other thread contained 2 questions, and the other question one has already been answered. The 1st paragraph was my initial question. The 2nd paragraph was after a little further diagnosis.




The heat is only coming out hot from the 2 driver's side vents, even though the passenger digital setting is set to 90* as well. The air coming out of the 2 passenger vents is cool to lukewarm at best. I know these HVAC systems can be a bear, however I wasn't sure if there might be an easy thing or two to check without having to tear the whole dash apart. I can live with it, however the wifey is always cold, so if it is something easy to check/test/diagnose/repair then I can spend a few moments and give it a whirl. I have the Bentley Service Manual, but couldn't find anything that would help. The rear vents in the middle are putting out hot air as well.




I pulled off the engine cover to get a better look at the water valve this weekend. I felt both hoses 8 and 9 in the picture below from BMWfans.info that shows the view of the water valve and associated hoses, and they both felt the same temperature, burning hot, so I'm guessing maybe the water valve is still functioning correctly? If so, is there an easy blend door to search for under the dash that is not buried behind 1,000 different things? Again, the driver's side heat is very hot, while the passenger side is just lukewarm, but not cold, as it was last week. Both digital temperature displays are set at 90 degrees.






http://ills.bmwfans.info/8ie.png

[motion]

Both hoses can feel hot but flow may be restricted, the pump aids in flow. Both heater valves fail in the open position. I assume the coolant is clean. The heater valve may be in need of replacement or rebuilding. There's a write up on E38.org that may help in testing the heater valve. I'd suggest insuring that the valve/pump/control is functioning properly before getting into steppers and flaps.

http://www.laczik.org/BMW/repair/E38_AC/E38_AC.html

[Chrisannagenna]

Both hoses can feel hot but flow may be restricted, the pump aids in flow. Both heater valves fail in the open position. I assume the coolant is clean. The heater valve may be in need of replacement or rebuilding. There's a write up on E38.org that may help in testing the heater valve. I'd suggest insuring that the valve/pump/control is functioning properly before getting into steppers and flaps.

http://www.laczik.org/BMW/repair/E38_AC/E38_AC.html

Motion: Thanks for the reply and the link. So to clarify, if I remove the connector on the water valve which removes the power source, they should both default to the open position? This was a 1 owner car with 114,000 miles, and it looks like the water pump and radiator were just replaced before I purchased it. With that being said, the internals of the water valve could still be a mess inside, thus keeping the passenger side valve from opening/flowing correctly, however the current coolant looks brand new.

[motion]

The PO changed the pump and radiator for a reason. Remember the valve may/may not be the problem but it would be nice to remove the valve and confirm the condition and operation of both the valve and pump, I don't want you to get carried away but what condition are the heater hoses and other hoses, just saying with 114K on the clock it may be time to change them as part of good maintenance which would allow you to check out the valve/pump. As always do as you feel is best.