RE: 84 4kq windows intermittent - fixed!

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

> Why replace it again with a THermal Breaker.   And what is a THermal
> Breaker.  My 4kq intermitantly get the same problem and the switch is
> fine.  Seems like the problem is inside the door in the wiring because
> if I wiggle the wires it works again.  has worked fine all summer
> though, thank god.  I suspected a loose conection but could not find it.
> 
... beacuse when the window reaches the end of its travel it will cause the
motor to draw more current, which often will exceed the current rating of
the fuse.  This may also happen if the window (or sunroof) starts binding.
The whole idea behind the thermal breaker is that it temporarily removes
power in these situations to prevent the motor from burning up.  If you
decide to stick with fuses, please let me know where you buy them from ...
I'll see if they are publicly held ... :-)

A thermal breaker is a device very similar to the bimetallic heated switches
you find in turn-signal or Christmas light flashers ... or even the
Thermo-time switch.  The breaker is heated by the current flowing through
it, and once the current is high enough to create enough heat the switch is
opened which breaks the circuit.  Once the circuit is opened the breaker
cools and eventually connection is reestablished.  Normally you have taken
your finger off the window switch by this time ...

BTW, if you have an intermittent problem that might be related to a break in
the wiring going to the door, you might want to dig into that ASAP.  Thermal
fuses can also fail in a way that causes them not to open ... and you might
end up dealing with a smoking wiring harness someday.  That said, it still
might be the switch ... they can be intermittent as well, and I would
actually suspect an intermittent switch more than a faulty thermal breaker
...

HTH!
Steve Buchholz
San Jose, CA (USA)