rear defroster won't stay on when button is released
 

When one pushes the rear defrost on my mother's 420SEL, the button light comes on only for as long as it is held down. The defroster definitely doesn't work after the button is released. So the button light goes off when you take your finger off the button thus not hold it in anymore. I am trying to be very descriptive here; I've tried searching but wasn't coming up with much luck on this problem.
Thanks
David

bump

My car has the same problem in extremely cold weather, once it warms up, it works again like it should. I would suggest cleaning the switch, but I don't know if that will help. It is possible that the metal connectors that are engaged bend away from the contact point in the low temperature in my case that is. In your case, if it happens all the time, it might be a problem with the relay. Come to think of it, the relay is what holds the crrent flowing through the circuit since the defroster is automatically switched off after a period of time, so it would probably be better to check the relay instead. I'd check both :)

xp

Where is the relay located?
Thanks
David