whitedavidp
Member
- Joined
- Oct 25, 2010
- Location
- Near Seattle, WA
Some time ago, the original rear window defroster stopped working and I replaced it with a Frost Fighter kit - described here. As I pointed out in the final post to that thread, after a while, the Frost Fighter stopped working and it appeared that parts of the grid had burned/scorched.
After the Frost Fighter died, I decided not to replace or try to "fix" it. Instead, I decided to try using one of these heater/fan units wired to the power supply lines that fed the wire grid(s) and therefore controlled by the normal defroster switch (which I again point out has no relay like later model years but does have a light). I felt this was possible and safe because the fuse for the defroster circuit is 16 amps and the heater/fan is listed as 150 watts (which at at 12 volts DC is equal to 12.5 amps). The unit had a 3-way switch (off, on low, on high). But on low it really didn't do anything much. So I had to run it on high.
I used this a few times and it worked better than nothing. But then I started to get no illumination on the switch and nothing from the fan/heater. I tested with the switch in the on position and got no voltage at the hot wire that originally fed the grid and was now used to power the fan. The fuse was OK. So I decided to suspect the switch itself.
I managed to remove the switch and found the pretty heavy duty connector looking like it has been seriously overheated.



With the switched removed, I was not able to get any continuity between any of the spade connectors with the switch in any position.

So I figured the switch itself was dead as well and I proceeded to open it up. That was not a good idea as there is a ball bearing, some tiny springs, etc that have to fit in there somehow - and I am not at all sure how. But it would seem the switch was also shot anyhow.
Sadly, I do not know at what point this damage all started to happen. And I don't know if this was exacerbated by the Frost Fighter or the heater/fan unit.
I am also not sure what to do now. So I would appreciate any suggestions. Thanks!
After the Frost Fighter died, I decided not to replace or try to "fix" it. Instead, I decided to try using one of these heater/fan units wired to the power supply lines that fed the wire grid(s) and therefore controlled by the normal defroster switch (which I again point out has no relay like later model years but does have a light). I felt this was possible and safe because the fuse for the defroster circuit is 16 amps and the heater/fan is listed as 150 watts (which at at 12 volts DC is equal to 12.5 amps). The unit had a 3-way switch (off, on low, on high). But on low it really didn't do anything much. So I had to run it on high.
I used this a few times and it worked better than nothing. But then I started to get no illumination on the switch and nothing from the fan/heater. I tested with the switch in the on position and got no voltage at the hot wire that originally fed the grid and was now used to power the fan. The fuse was OK. So I decided to suspect the switch itself.
I managed to remove the switch and found the pretty heavy duty connector looking like it has been seriously overheated.



With the switched removed, I was not able to get any continuity between any of the spade connectors with the switch in any position.

So I figured the switch itself was dead as well and I proceeded to open it up. That was not a good idea as there is a ball bearing, some tiny springs, etc that have to fit in there somehow - and I am not at all sure how. But it would seem the switch was also shot anyhow.
Sadly, I do not know at what point this damage all started to happen. And I don't know if this was exacerbated by the Frost Fighter or the heater/fan unit.
I am also not sure what to do now. So I would appreciate any suggestions. Thanks!