Heater always blowing warm

[Rory525]

Ive noticed the air from the drivers side windscreen vent is always luke warm, even when I have the temp guage down to full cold. As far as I can feel its the only vent thats doing it, seems ok from others...

I was wondering why I was getting so hot in the summer, I just put it down to it being a black car

What will be causing this ? Is this the heater sword thingy? I wonder if this could be related to my small coolant leak ?

Anybody with any knowledge on this?

[632 Regal]

heater valves under the hood on the firewall are probably gunked up and not closing. I think Shogun has a link to that somewhere.

[632 Regal]

http://www.bimmer.info/forum/showthread.php?t=1369&highlight=heatervalve

[Rory525]

http://www.bimmer.info/forum/showthread.php?t=1369&highlight=heatervalve

Cheers guys, thanks for the link regal will read through it.

[632 Regal]

I knew i'd find something, just took a while.

http://www.bmwe34.net/e34main/Maintenance/Electrical/HeaterValve.htm

[Rory525]

I knew i'd find something, just took a while.

http://www.bmwe34.net/e34main/Maintenance/Electrical/HeaterValve.htm

I will try the tapping on solenoids trick tomorrow, see if it frees them up. Good chance things have become sludged up as the car is 15 years old !

Im reading through every thread on this I can find now too lol

[Rory525]

I have a feeling my aux water pump isnt working any more as it takes ages for my car to give me cabin heat when started from cold.

[Rory525]

while I think about it , I used to hear my heater valves *thunk thunk* occasionally from the inside of the car ... and I dont hear this any more.

Does the thunking noise they make mean they are working properly?

[pundit]

while I think about it , I used to hear my heater valves *thunk thunk* occasionally from the inside of the car ... and I dont hear this any more.

Does the thunking noise they make mean they are working properly?
The do click as they open & close in order to regulate the temp.
They require power (12volts) to stay in the off position.
So loss of power to the valve solenoids will result in full heat.
Handy when your heater valve fuse blows at 20 below!
This also accounts for the slight burst of heat out of the vents after stopping and restarting the engine with the heater in the off position. With the ignition off the valves open and some heated water will syphon into the core until power is reapplied and the valves close.

The 12volt supply is constant with the grounds (one for each valve) being switched to power the solenoids and operate the valves.
Provided there is no issue with power, sticking is often caused by the failure of the seals that are supposed to prevent water entering the solenoids.
Crap then builds up between the valve shaft and solenoid causing sticking.
Tapping may help free the valves temporarliy but the condition is generally terminal.

[Rory525]

Thanks for the info Pundit.

I will have a poke about the valves tomorrow, pretty sure they are playing up. I also think my aux pump has gone as the cabin heat isnt that great, particularly when car is idling.

[Rory525]

Ok I took a hammer to the valves today and the drivers side one seems to work properly now, I can hear it clicking away. I can get fully cold air from the drivers vent now which I couldnt before.

Passenger side one seems to be knackered though, but its stuck on almost cold so its not really a problem.

Hope they stay working so I dont have to replace the valves.

QUESTION - does a 1991 525i M50 have an Aux water pump ? I couldnt see any sign of it. Maybe it was only the 535i ? Or im blind

[JonE]

Should have the aux pump, check the link, http://www.bmwe34.net/e34main/Maintenance/Electrical/HeaterValve.htm
look there at the first picture that shows the valve assembly attached to the aux. pump. They come out together if you're refurbing this item. Then you separate the two components. Check the wiring to the pump, this could be the problem, mine was completely corroded at the pump and needed replacement. Perhaps you will be luckier?
JonE

[mistertonylee]

try flushing the heater valve. there is a website out there (don't remember where, sorry) with instructions and pictures and everything!!

probably not the heater sword thingy, and the coolant leak would cause your heat to be cool, not your a/c to be warm.


Tony