Heated rear window doesn't appear to be working

[gmsclassics]

Strange topic for those in the northern hemisphere at this time of year I know but here it is mid winter and temperature today didn't get above 9ᵒC. I hardly ever need to use the HRW, but did the other day in the rain and cold and the rear window didn’t clear at all.

Started to check today, with the switch on there is power at the nearside connector and a good earth on the offside. However, using my multimeter I could not seem to get any contact between the two spade terminals on the glass itself, no voltage at the offside when there clearly is at the nearside and when I tried to measure the resistance, meter indicated there was no connection at any of the meter settings. Glass and the heater matrix appear in good condition although is almost certainly original. Certainly no visible signs of any breaks.

Checked the other car and strangely, that displayed exactly the same symptoms.

Am I missing something or is this telling me all of the heater ‘lines’ are broken? I had seen a YouTube video about repairing these but that assumed only the odd one had broken.

Is the window glass actually supposed to heat up by any measurable amount?

Advice appreciated

Geoff

[dollyman]

Easy way to check it Geoff is to use a test light.... One end to earth (door catch is good) then other end to the elements on the glass. You can test each one then, works every time for me

Tony.

[gmsclassics]

Thanks Tony, that just confirms that not one element on either car's HRW is still working. Furthest I got along any of the individual elements was about three inches! I suspect it is yet another effect of the high UV in NZ that has destroyed whatever was originally holding it together. Not worth doing anything about I suspect.

Geoff

[dollyman]

Hi Geoff, in the past i have had some success with this stuff
https://www.ebay.co.uk/itm/LOCTITE-3863 ... Swb3lc3cw8
I presume they will post to NZ? Or one of your sellers might stock it. It is time consuming but a lot cheaper than a new window, also just repair every other element.

Tony.

[MIG Wielder]

Strange topic for those in the northern hemisphere at this time of year I know but here it is mid winter and temperature today didn't get above 9ᵒC. I hardly ever need to use the HRW, but did the other day in the rain and cold and the rear window didn’t clear at all.


Is the window glass actually supposed to heat up by any measurable amount?

Advice appreciated

Geoff

Hi Geoff, I did a thermal image of my HRW. And the answer to your question is that after 10mins with the engine running it gets to about 35 deg C. I'm not sure about the absolute accuracy of this as the rear window is reflective. I'll try again at night sometime. Certainly it got "hand hot" - about 37 deg C.
When I was repairing mine I had to use a magnifying glass to see a break across all the elements probably caused by a ringed finger running across the elements when wiping it. I found that a sharp pointed DVM test lead was not good at measuring the voltage. I used a short piece of copper braid in a croc; clip placed across the element in question.
Hope it gets sorted,
Tony.