Rear Demister Repair - Success

[PhilNW 47]

I have heard good and bad reports of success in repairing rear demisters in general not just 205s. When I bought the car only the top 3 wires worked. You could see where someone had gone across some of the wires breaking them.

 

Tried a repair a few years ago but no success so have recently had another go. The biggest problem was actually finding the defects in the wires, some were obvious a lot were not.  Some wires had one defect some had 3.

 

The way I found to find them which has worked for me was a mutimeter set to voltage and a direct earth to battery not to a body earth (disconnect the earth lead of the demister). I found that with the wires being resistances in parallel you can get unreliable readings.  With the demister switched on I worked my way every 50mm along each wire nudging the wire with the meter probe checking for voltage. The defect will eventually show as either approx battery voltage or zero and they may be practically invisible.

 

Clean the wire and the surrounding area carefully. I used pinstrip detailing masking tape to define the length and width of the repair area (be generous) . Applied 4 coats of Silver Conductive Paint per defect with success. Using a carpet steam cleaner is a very effective misting device to check repairs. However may will have to repeat the process to get complete repair on a wire. Total cost £15 for the paint and £3 for the tape.

 

In my case I repaired 21 defects on the demister (No wonder it did not work). Very happy with results now winter is imminent.

  

 

[Ozymandis 98]

I did this yesterday on my wife`s daily driver, a small bulb with one side earthed and the other connected to a wire with a scrunched up wad of aluminium foil as a brush applied to the supect elements, is my favoured bit of tackle.

Test probes are a bit worryingly sharp, pointy and scratchy for my liking. Store the vial of silver paint upside down and it can last for years, mines at least 15yrs old and has done maybe five or six 205 demisters and it was fine to use. The stuff I use is from a model railway supplier in Devon called Peco.