Porsche Enthusiasts Club Forum

Hi All,
I'm trying to trouble shoot the rear window defrost. The switch light comes on when pressed. Fuse is ok.

I've used a little current checker with a bulb (dunno the tech name ) - putting the crocodile clip on the right hatch gas shock and the prong on the left. With the switch on, the bulb illuminates, but not brightly - so current is flowing, but...

...the rear window doesn't defrost!

Does any of it defrost? My old Golf only the top two bars worked. Looking closely I was able to see the breaks in the circuit and tried to patch them up with some silver circuit board paint. Didn't work they just burned out again, might be worth a try though. I just noticed halfords do a kit that might work.

http://www.halfords.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10151&storeId=10001&partNumber=190363&langId=-1&cm_mmc=Googlebase-_-Windscreen+Wiper+Blades-_-Na-_-Granville+Rear+Heater+Repair&%24%24tid=JVa4zPNK2aoFQdp36_kAJxTGQZwCoSnupw-a_A-TT1WCYQpWt9MUd_Z5Boc7HT2W

I had same problem and itwas a poor earth on the rh strut.Also might be worth checking the relay

Mine doesn't demist (we don't get frost this far south... ) and it's quite obvious why - the wire to the hatch strut is broken. But it actually looks cut. Would there be any reason for this? If I re-connect it is it possible the battery drains or some other weird electrical problem manifests? I didn't think it would be too much of a problem until I had to reverse out of a parking space!

D

I've checked the lines on the window and they seem intact.

Is the earth wire obvious on the RH side?

Is the relay one I can replace from Hal's?

Swop the relay with another under the bonnet and to try the earth,connect the earth tag on the rh strut direct to earth to check if it works.

The previous owner on my car put new connectors on mine. it certainly demists well!

Hence I'd say to give the connections a good clean with switch cleaner and sandpaper.

I've now managed to detach the right hand connector from the window

Anybody know of a conducting adhesive so I can glue this sucker back on?

I re-attached mine with soft solder and a fine soldering iron but be careful not to put too much heat into the glass.

You probably use an epoxy with iron filings included or we used to use a metal based epoxy at work called "devcon" which had a high metal content but not sure how well this will conduct.

thanks David I'll try the low heat solder approach and look into finding some of that glue.

ok I soldered the connector back onto the window but still no defrost...

Hi.

How about measuring the resistance? If its open circuit, i.e. measuring infinite, you know for definite its the heater strips. If you can measure resitance you can be pretty confident that its something else i.e. wiring, connectors, fuse etc

Hope this helps.

Ben