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My rear defroster does not work, and I found the reason. One of the 2 connector tabs has come unsoldered from the copper patch on the glass. I am competant to solder it (I've fixed other car's defroster connectors), but I'm looking for anyone else who has done this on the MX-3? Any thing to be careful of? I plan to pre-heat the glass in that area with a hairdryer to keep the temp shock down, and use minimual heat to flow the solder, and of course, speed!

Thanks,
Jim

Flux is your friend......

What is Flux, i have this problem too...

Flux is a compound used to aid soldering. It is a paste applied to the metal surfaces that cleans all oxide from the metal when it is heated. This aids in making a good connection with the melted solder. There are several kinds, some are acid based and very corrosive to thin copper, like the defroster lines.

it is sometimes included in a hollow core solder wire, so it is applied at the same time as the solder.

It's not going to specifically help you without also applying heat and probably some additional solder. There might be enough solder there to just "reflow" or remelt the existing solder, but you need to consider it might have not been enough in the first place, if it just fell apart. Or maybe it was just a bad job, a "cold" solder joint (not to be confused with a cold soldering iron) where the connection moved as the solder was going through it's plastic phase as it cooled to a solid.

Jim

what? Flux on automotive wiring I think not, bad idea. Get proper automotive solder its acid free and meant for automotive wiring you clean the existing wiring with some crocus cloth or very very fine sand paper, I prefer crocus clotch as it leaves no residue. Preheat the glass with a heat gun if its at room temp, if its cold use a hair dryer to prevent cracking when you go to solder the joint. Apply the tip of the soldering gun to the copper contact for a few mins then apply some fresh solder to it for a base to work from, then put the contact on the window and press that to the glass with the tip of the soldering iron and wait until it sinks back into the solder you applied earlier, apply a little more and use a flat head screwdriver to hold in in place while it cools. Solder flux is meant for household plumbing and not automotive purposes its a totally different type of solder so flux in a no no. I am a journeyman heavy equipment tech with some 15 years of automotive experience and have never ever used flux on automotive wiring.

Newfie_dan wrote:what? Flux on automotive wiring I think not, bad idea. Get proper automotive solder its acid free and meant for automotive wiring you clean the existing wiring with some crocus cloth or very very fine sand paper, .... Solder flux is meant for household plumbing and not automotive purposes its a totally different type of solder so flux in a no no. I am a journeyman heavy equipment tech with some 15 years of automotive experience and have never ever used flux on automotive wiring.

If you had read, you would see I said acid flux was bad. Automotive wiring solder has rosin flux in the hollow core of the solder.

There are differnent types of flux, acid is indeed mostly for plumbing. I am an Electrical engineer with 37 years experience, many patents, and have had my designs flown in satellites, the Shuttle, and the International Space Station. I know my solder!

I was referring to ninjaskill's reply that "flux is your friend" not to yours jmdearras

Well, today was a nice, warm, clear day, perfect to try soldering the connector tab back on to the rear window. I could tell at once the factory solder was a lower temp melting solder than my electronics solder, but I mixed a bit of the new solder into the old, to get some flux on the surface of the tab. I then held the tab against the window and applied the iron to the back of the tab, top and bottom, to melt and reflow the solder.

All went fine, it held tight, and I believe I have a rear defroster again, can't wait to test it!

Jim

Newfie_dan wrote:I was referring to ninjaskill's reply that "flux is your friend" not to yours jmdearras

whoa, dude i meant rosin flux. sorry, should not assume that when you are shopping for solder accessories that you are standing next to galvanized pipe

i have had college education on board level circuitry and have made my own amplifier/rectifier circuits from scratch
not saying i have the awesome experience that jmdearras has though.

Well, it failed the first test, did not remove fog from the rear window. Got out the old Voltmeter, and found no volts across the grid. A short tracing session led to a relay that sounded OK, clicked and all, but when I unplugged it, it fell apart, burnt-up.

Tonight I dig into my parts car...

jmdearras wrote:Well, it failed the first test, did not remove fog from the rear window. Got out the old Voltmeter, and found no volts across the grid. A short tracing session led to a relay that sounded OK, clicked and all, but when I unplugged it, it fell apart, burnt-up.

Tonight I dig into my parts car...

bummer, my headlight relay nearly caught fire and i kept wondering what the smell was
at least you found the culprit.
AND you have given some priceless advice to diagnose and repair said problem.

Raining too hard from the hurricane remnants to fish the "correct" relay from my parts car, so I grabbed one of those rubber-sleeved relays from under the hood near the passenger strut. A/C relays, I think. I removed it from the sleeve and it had the correct plug. I plugged it into the hanging plug on my DD and it worked! I'll neaten stuff up when the rain stops.

Jim

Well, the windows still didn't defrost. Volts were there, and ground. Basically, all traces are open, they are VERY thin in the middle of the glass, and a volt meter can find the first break in every line. Not patchable.

This hatch is from my '92 parts car, as the other hatch was damaged in a rear end collision of some sort. The wing was smashed in one place, and the lower brake light area glass was shattered. Main glass and overall frame seem fine.

I'm going to check the defroster traces on it, if OK, I'll see if I can repair the damage and put it back on.

How hard is that small glass piece to get, and what do you think it will cost? This is a VERY low-budget operation, and I'm not beyond using a hard lexan or other acyrilic instead of glass for that small place.

Any thoughs, advice?

Thanks,
Jim

jmdearras wrote:Well, the windows still didn't defrost. Volts were there, and ground. Basically, all traces are open, they are VERY thin in the middle of the glass, and a volt meter can find the first break in every line. Not patchable.

This hatch is from my '92 parts car, as the other hatch was damaged in a rear end collision of some sort. The wing was smashed in one place, and the lower brake light area glass was shattered. Main glass and overall frame seem fine.

I'm going to check the defroster traces on it, if OK, I'll see if I can repair the damage and put it back on.

How hard is that small glass piece to get, and what do you think it will cost? This is a VERY low-budget operation, and I'm not beyond using a hard lexan or other acyrilic instead of glass for that small place.

Any thoughs, advice?

Thanks,
Jim

my advice would be if the defrost lines on the busted hatch are good, then just swap the hatch glass only.
I'm not sure how expensive it would be for that small glass piece in the hatch
i don't know where you live but I'm being rained out too.
there are mobile glass companies that would probably do the swap for you for a low price if you
don't feel comfy doing it yourself

I think you missed the part about "low budget". I'd love to just call a mobile glass company. But food comes first.