How to fix my Saab 900 S rear window demister/heater

[frolandus]

Hi,
I bought a real beautiful 1993 Saab 900 S.
Unfortunately the rear window demister/heater is broken.
I checked the fuses (the ones below the back seat) and they appeared to be OK ... :-?
The strange thing is that all the cables look OK (new and well connected). An other thing is that the indication light behind the button that turns on the rear window demister doesn't light up when you press the button.
Any idea if the button/indication light is controlled by another fuse ? :-??
Or perhaps any other suggestions on how to fix my rear window demister ?
Any help is welcome.
Thanks on forehand.
Frank mailto:frolandus@lucent.com.

[Paco]

Sounds like the button (switch) has failed, and it is not allowing current through when switched on, hence no light or power to the demister. Try another switch? I've no idea how they come out....Anybody? Anybody? :wink:

[Michael]

Yeah, just push it to the side and then it comes loose. I found that out waiting for a traffic light once and being bored.

[jnorris]

I have exactly the same problem on my car and it is a complete pain the backside. I had it checked at the last service and apparently power was flowing right up to the rear screen element. Much to my horror I was told the only solution would be an entirely new rear screen.

[john-w]

Sometimes the contact soldered to the screen comes away, this can be the feed side or the earth. Best thing to do is get a meter or test light and see if you have a feed to the rear screen, if you have, check the earth on the other side of the screen :!
Having said that the light in the switch should still work even if the screen contact has a problem :! :!

[LuukvdHeiden]

if you want to repair you rear demister, check out the relevant section in the bentley manual.

Before replacing the whole window, apart from checking the switch and the fuse, it is worth checking the relay which in my case (900s) is located under the rear seat. If it doesnt go 'click' when you switch on the demister, no current wil go to the grid at all.

[RM '92 SPG]

Does the light on the instrumnet cluster come on with the button? if so, the switch is not likly to blame. If not, the wiring to the switch from the fusebox or the switch itself may be at fault. I belive the rear defogger shares a fuse and partial circuit with he cigarette lighter.

-Rob

[saab_cruz]

i own an 87 saab 900 convertible, my defogger light comes on no problem, and stays on. but nothing gets defogged.

I checked all the connections and everything seems to be plugged in, fuse checks out and everything.

any ideas?

[cdaly]

There's a mercury switch on the rear LHS top upright. This is to switch off the demister when the top is down. See if that's loose or otherwise poorly.

[saab_cruz]

define LHS?

[cdaly]

Left Hand Side...

Look at the main upright {the one the hydraulic pistons connect to} and down near the pivot point there should be a little cylinder screwed on. If that's loose, try tilting it upright and upside down. If the demister works for one of those positions, that's the way it should be attached...

Sorry for no photos. Nobody's seen fit to present me with a digital camera yet...