Heat in footwell and upper vents...

[Qube]

Heat in footwell and upper vents...

Once I turn on the heat, the footwell and upper vents (defog) stay hot... even if I turn it back to cool. It seems that either they are designed only to vent heat, or something is wrong.

I haven't tried keeping it on cool and seeing if they heat up. Not yet ;)

Any thoughts? Is that by design?

[e34it]

Mine does it too on my M5 , i got no real concrete answer or suggestions to anyone this might have happened to before. I am assuming its the electrical heater valve thing in the engine compartment next to the fuse box. Im gonna try and replace it see if it helps. Let me know if u figure anything out..

[molesz]

Hey, mine does that too! (520i M50B20). I am also convinced that the heater valve plays with us. Its quite an expensive replace ... any suggestion on how to repair it (when it is not stuck)?

[genphreak]

Hey, mine does that too! (520i M50B20). I am also convinced that the heater valve plays with us. Its quite an expensive replace ... any suggestion on how to repair it (when it is not stuck)?

They r easy to get at against the firewall at the back of the engine bay, surely they are worth getting out and cleaning...

I'm gonna do mine soon- I bet its sludge. I recently cleaned my cooling system and found some, but not much, however my passenger side heater has never worked. These valves are surely amongst the first things to be affected by sludge build up... suggest you guys consider flsuhing your blocks, radiators and changing ur coolant when u do it to help prevent further trouble...

Tip: jic u aren't aware- everyone says 'make sure to use the original BMW stuff' too.

:) GP

[Paul in NZ]

i am sure there is a write up on the heater valve fix somewhere,apparently tapping the valve bodys can sometimes free those suckers loose....

[pundit]

Heat in footwell and upper vents...

Once I turn on the heat, the footwell and upper vents (defog) stay hot... even if I turn it back to cool. It seems that either they are designed only to vent heat, or something is wrong.

I haven't tried keeping it on cool and seeing if they heat up. Not yet ;)

Any thoughts? Is that by design?
The heater valves are normally open by default. They require power to close.

Heater Valves (http://www.bmwe34.net/e34main/Maintenance/Electrical/HeaterValve.htm)

I had a problem for a while with hot air coming from the drivers side demister vent even with the heat controls in the off position. After flushing the cooling system and replacing the coolant with the genuine bimmer stuff I still had the same problem. I read about tapping the heater solenoids (see above) and that seemed to do the trick. Just make sure you tap them with the heater in the off position and the motor running. Even with correctly operating heater controls (set in the off position) you will notice that if you shut the motor off for a short while and then restart you will actually feel hot air coming out of the vents for a few seconds. This is caused by hot coolant syphoning into the heater core when the valves open after losing power upon shutting off the engine. As soon as you restart the heater valve solenoids re-close and the heater core cools down. It took me a while to work this out, but a multi-meter soon confirmed what was going on. I think I can see why the valves are designed to remain open without power. Try a European (or North American) winter at 20+ below. If they worked in reverse just imagine losing power to the heater valve solenoids... cold ain't it! ;)

[JonE]

A very nice description of the water valve function, Pundit! No wonder I like the nearly instant heat I get living here in Minnesota.
Yep, give the tops of those a tap and see if you can get them moving again. Replacement isn't too bad, just pinch the small hoses with some long nose vise-grips so you don't lose alot of fluid. The auxilliary water pump is also connected to the water valve, check the wiring. I had fried wiring and needed to replace that pump when I did mine.

[Qube]

I'm glad I'm not the only one with this problem!

Tomorrow morning I'm going to leave it on cool (finally warm enough to do that) and see if it says so. My passengers complained there wasn't any heat coming from their footwell also... or the passenger heated seat. LOL. I'll check it tomorrow.

If there's still daylight when I get back tomorrow, I'll check the solenoid for 'clicking'. Thanks!

[pundit]

A very nice description of the water valve function, Pundit! No wonder I like the nearly instant heat I get living here in Minnesota...
If you haven't seen the movie 'Fargo' then it's well worth a look. ;)

[Tcdoe]

The passenger side temp control seems to be stuck on hot all the time, quite annoying in the summer. In addition the car takes forever to heat up and when it does the airflow is crap, not hot nor cold. Just warm and sort of coolish. I guess it's the same problem as you guys have? Oh btw, the car doesn't have AC.

[Qube]

Well... I 'tapped' the solenoids today. Just removed that plastic cover and tapped away while someone 'played' with the climate control.

Originally, it made a very soft and weak sound. After a bit of tapping, it makes a solid click both ways. Checking it tomorrow during running.

[Qube]

Well. I love this place.

It works fine. I turned from full heat to full cool during my 45km trek. Worked great. Going to try it on the way home as well, but I have no doubts ;)

[Jeff N.]

The heater control valves tend to fail as they age. The seal between the plunger and solenoid goes, allowing water into solenoid. This makes the unit sticky and ultimately fail. The E28 unit is reportably rebuildable; the E34 unit is not.

When one get's sticky, it's usually just a sign that it's on it's way out.

Jeff

[Qube]

Mmmmmm... do they independantly control the left and right footwells?

I noticed today that although my side was nice and cool... the passenger side was hot and toasty. So , are they independant? :)

[Kalevera]

Yes - hence two plungers -- one for each side.

[Pnoble]

I've got a similar problem ('94 525i)... only hot air out of the passenger side footwell and defog vents. I replaced the Heater Valve, but it didn't fix the problem. I found this URL http://www.homeofsbc.com/Fixes/Ins__Temp_/ins__temp_.html that speaks of cleaning a microswitch behind the Airflow Control Panel that may the culprit. It's free, so it's worth a shot! I'll let you know if it works...