Rear defroster not working properly?

akiragost · Post by **akiragost** » Sun Feb 22, 2015 2:02 am

So the rear defroster on my 5g doesn't seem to operate properly? When turned on, after a long while, I can notice it does defrost, but literally only defrosts the tiniest amount where the lines run across the window, and sometimes it just does nothing if anything at all. Any idea how to resolve the issue, or at least where to start trouble shooting?

G-lude · Post by **G-lude** » Sun Feb 22, 2015 9:13 am

My wing mirrors have a similar issue, I've just never got round to looking at it ): wonder if they have similar electrical components which might fail?

K30DPC · Post by **K30DPC** » Wed Feb 25, 2015 6:44 am

While switched on check the voltage on defroster connectors. There should be battery voltage. In case some of the lines doesn't work while defroster switched on you can try to find special paint conteining silver and try to fix them. I know motorspares does them but I do expect you can find it on egey or halfreuds

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Wed Feb 25, 2015 8:45 am

If they are all working but only slightly, I'd suggest the earth on the demister is poor.

But as Mario says, check for voltage at the terminals first, then check resistance between the ground terminal and battery earth to see if that's high.

If you have low (or no) supply voltage, check/change the fuse and relay, which are in the footwell fuse box.

Post by **Lude-dude** » Wed Feb 25, 2015 9:24 am

rear demister unit is brown or black box in the boot under parcel shelf

could make sure its connected

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Wed Feb 25, 2015 4:29 pm

That's bit different to 4g's... My apologies if so!

akiragost · Post by **akiragost** » Wed Feb 25, 2015 7:48 pm

So where abouts should I hunt for the ground for this? And what's the name of these paints with silver in it??

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Wed Feb 25, 2015 8:33 pm

The connection on one side of the demister will be live (+12v) and on the other side will be ground.

Assuming that's the same set up as a 4g at least!

If in doubt... Have a look in the 5th gen service manual (available in the wiki-lude ^^^^ )

K30DPC · Post by **K30DPC** » Thu Feb 26, 2015 1:59 am

What wurly said. Bare in mind that some of the lines are your aerial (not sure if all 5gens have it but mine does). This are slightly different and easy to recognize. Heating lines going from side to side and there shouldn't be any connections between them.

For the paint/glue just type "demister fix" on ebay or explain what you looking for in your local auto shop. Use it only when you can see that some lines doesn't work. It wont fix any other issue with demister.

akiragost · Post by **akiragost** » Thu Feb 26, 2015 8:58 pm

So I took a look in the boot, I think I discovered what could be the issue. There's a wire with a brown connector that connects to the a black box, from that black box comes out another wire with a brown connector, it's connected to the box, but on the other end it's just hanging, opposite it is another brown connector which is just hanging, these two don't connect though so I believe something is missing in between?? Any ideas guys?