Help! Heat won't shut off...
- Thread starter razi
- Start date
jhjacobs
Well-Known Member
I've got the same problem. Part of the problem is that I was getting hot engine air pushed up to the heater fan unit. I significantly reduced this by installing a new rubber seal between the firewall and the hood. BMW still has the seals but I elected to buy some generic material from JC Whitney which seems to be nicer, cheaper, and seal very well (part number ZX132565N - $29 for 25')
Since my problem is not entirely cured I suspect that the heater air diverter flap is also not working. I've gone through my parts manual and there appears to be a "bowden cable" between the heater control lever and the air diverter flap in the heater box. I suspect that the cable could be broken, disconnected, or the air diverter flap is jammed with debris. Major dash surgery is needed to get in and check it all out. I am determined to fully resolve this problem but it may take me a while. I'll write back if I learn more. Hopefully someone with some direct experience will chime in.
Since my problem is not entirely cured I suspect that the heater air diverter flap is also not working. I've gone through my parts manual and there appears to be a "bowden cable" between the heater control lever and the air diverter flap in the heater box. I suspect that the cable could be broken, disconnected, or the air diverter flap is jammed with debris. Major dash surgery is needed to get in and check it all out. I am determined to fully resolve this problem but it may take me a while. I'll write back if I learn more. Hopefully someone with some direct experience will chime in.
The temperature control of the heater box simulaneously actuates two flaps. This is shown in the image below. The heater cable modulates the first flap, via the t-lever at center, and the solid link ties to the second flap. The spring helps pull the two flaps closed. Make sure that: (a) the clip that holds the cable sheath is secure; (b) the cable nut to the t-lever is tight; (c) the solid link tie-nut, at lower right, is tight; (d) the spring is not broken. If all of this is in proper adjustment, it is possible that the foam gasket material used on the flaps has completely disintegrated. This will require that you either get a new box or rebuild the current unit. I just completed the latter. It isn't that bad, once the box is out. You can check out additional images at http://www.vranedom.com/vraneman/bmw/heaterbox.
put a forward slash after "heaterbox" to get to the directory.