Been getting colder here at night the past few weeks. The past few mornings I've walked out the door to see frost on the car. Which never bothered me... til I got this Subaru. I turn on the defroster as soon as I start the car, and by the time I get to work (roughly 15 minutes drive) about 1/8" of the frost on either side of each line has melted away. All of the lines work, they all melt the frost, just not very well.

Is it just mine or are they all like that?

I often have to parallel park at work and its no fun when you can't see out the back window.

I would probly start by checking the wiring that goes from the body of the car, to the body of the hatch lid. Where they join is that little flex tube, with all the wiring in it. I have seen where the electrical current is cut because there isnt enough wire connection because the flexing of the wire has broken the internal strands.

 

I hope that makes sense.

 

I have also heard that doing the alternator upgrade helps alot on the older Subies with smaller alts. To much power consumption by the rear defrost then the alternator can put out.

It's a sedan, so no hatch to worry about broken wires.

 

I'm not entirely sure how these things work really. Is it resistance that makes them heat up? So if it's not getting enough current from the relay then it won't get as hot?

You might stop by a Tint shop, and ask their opinion. Some of them deal with installing aftermarket rear window defrosters, and might have input on this.

Well I found some info about how to test the voltage, but haven't tried it yet. You have to remove nearly the entire back half of the interior of the car to get access to the wires.

Well I found some info about how to test the voltage, but haven't tried it yet. You have to remove nearly the entire back half of the interior of the car to get access to the wires.

 

 

Start with square one. How is the alt output?

 

 

nipper

When tested about a month ago, 14+ volts at idle, and the tester showed about 75 amps at 2000 rpm, and 100+ amps max output. Car has been running flawlessly since I fixed the battery terminal issue, no lights dimming, no flickering, nothing to make me think that those numbers would have changed significantly in the meantime.

 

I am on the same page, thinking that the voltage must be too low, wondering if that full 14 volts is making it all the way to the back window, but I have to pull pretty much half the car apart to get to the wires to find out.

[...] I turn on the defroster as soon as I start the car, and by the time I get to work (roughly 15 minutes drive) about 1/8'' of the frost on either side of each line has melted away. All of the lines work, they all melt the frost, just not very well.

Is it just mine or are they all like that? [...]

 

They're more of a ''defogger'' than a ''defroster'', although eventually they'll melt ice.

 

[...] wondering if that full 14 volts is making it all the way to the back window, but I have to pull pretty much half the car apart to get to the wires to find out.

You should be able to just measure the voltage on the conducting traces on the window. Put one meter probe on a conductor as close as possible to the trim on one side, and the other probe similarly placed on the opposite side. (It might require two people.) Obviously, try to not damage the conductors. If the wiring, etc., is okay, the voltage should measure only slightly less than the approximately 14 volts measured at the battery.

Edited November 6, 200916 yr by OB99W

They're more of a ''defogger'' than a ''defroster'', although eventually they'll melt ice.

quote]

 

Ditto. No problem with my rear defroster but I have to scrape what's on the outside of the rear window if I dont want to wait for rear clear vision.

What I do (if this is a wagon) is use the rear washer. It really helps.

 

nipper

Meh, maybe I'm just spoiled by my Lincoln. I think that thing could fry an egg on the rear window. It's 100% clear in about 3 minutes in the morning. It'll even melt away a pretty moderate amount of ice and snow in the winter.

 

I have to remove the back seat to put in the new (used) rear struts I got today, so I'll pull the trim panels off while I'm in there and check it out.