Rear Window Defrogger

I have DC current when I put the defroster switch on and my meter probles on the window connector tabs but still the defroster not work! I have Ford Taurus 2004 car.

Thank you for helping me answering the question on top.

Welcome to the forum!

Technically, if you have DC current, then the defroster should be working, at least a line or two. I suspect you meant voltage, you measured voltage at the window.

Was the voltage full battery voltage or something lower? If something lower, you might have a high resistance path that's limiting the current too much for it to be effective.

Did the window used to have tint on it that was recently removed? If so, the removal process may have damaged multiple grids. Or, if tint was recently applied, one of the sides of the grid may have been damaged when the tint was trimmed.

If you have a test light, you can check for breaks in the grids by connecting the clip end of the test light to ground and then moving the tip of the light across each grid from one end to the other. The intensity of the light should change gradually as you move along each grid. If you find an area where the light goes from off to full bright or vice versa, there is likely a break at that point. Or, you can look through the grid with a bright light on the other side of the glass. If you see an area where light appears through the grid, there is a break in that area as well.

There are small kits for repairing small breaks available from many auto parts stores and department stores. If it turns out one of the contacts where the wiring connects to the glass is broken, the safest solution would be to use some silver-bearing conductive epoxy. This is quite expensive though, but less than the cost of a new window.

-Rod

Hello Shorod:

Thank you for the reply. Yes I did check the voltage with a multi-meter and it was around 12V DC at the contact tabs.

There was no alteration done to the rear glass in anyway. The tab was broken so I used one of those kits you get at Canadian tire and ever since the fogger has not worked. Its been months though it hasn't worked as did not have the need during summer.

IN regards to test light you mean continuity test? I would be using http://www.valuetesters.com/Amprobe-VPC-10-Voltage-Probe-Continuity-Electrical-Tester.php using the audible continuity? Now should one end of the probe be on one of the tab for ground? that is not clear where there is "ground" on the glass.

Thank you for your help.

Is the repair kit you got from Canadian tire basically a very small vial of copper colored paint, meant for repairing the rear window defroster grid? If so, that paint won't handle the amount of current necessary, which is why I suggested you'll need to use silver-bearing conductive epoxy. You could also try soldering the tab back on, but then you risk breaking the rear glass due to the concentration of high heat.

One tab of the rear defroster will be ground and the other power. Each of the grid lines will have a certain amount of resistance from one side to the other.

What I was referring to as a test light is just that, it's a 12V light bulb with a probe on one end and a clip on the other. You clip the one lead to ground and the tip would be dragged across the grid. You could do the same with a voltmeter, but it would require more observation to monitor the condition of the grid. With your tester you'd want to use the voltmeter feature rather than continuity. However, for the cost of a test light (often around $5) it might be worth the cost to buy one.

-Rod

Thank you for your reply

I did not get any contininuity from the tab I repaired to the "ground" that is the black part just besides the tab. When you use the glue for tab repairs its supposed to "connect" to the surronding area and give continuity? In my case it does not :headshake , maybe that would be the problem

If that is true what do I use to make contact with the surronding and the tab? The tab is "secured" and is glued properly to the window.

Thank you for your time.

As I mentioned in both of my posts above, you should use silver-bearing conductive epoxy to connect the tab to the window. What did you use? You should have continuity from the tab to the conductive material around where the tab is mounted.

The conductive epoxy can be purchased from a good electronics supply store (not Radio Shack) or online, such as this place (http://www.mcmelectronics.com/product/21-2225).

-Rod

Thank you for all your help Rod. The defrogger is working perfectly after following all your instructions. Thank you for your help and time.