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2002 VDC Outback sedan
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173 Posts
Discussion Starter · #1 ·
Anyway to boost it up a bit? I can see the lines where it is trying to work but it doesn't get past that.

Same day, same amount of frost, my thunderbird will clear the back window in a couple minutes.
 

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01 VDC, 05 R Sedan, 06 BAJA EJ257
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16,315 Posts
Check the connections in the rear harness and the plug on the element. Specifically the ground. Window tint will also effect it. The film absorbs the heat, especially if the film is carbon. Think heat dissipation.
 

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Meh.
I has wagons.
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12,372 Posts
Something isn't working right.

Kaylee will clear a heavy frost in a few minutes.
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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18,669 Posts
is every line working? There are repair kits for broken lines.
 

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2002 VDC Outback sedan
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173 Posts
Discussion Starter · #5 ·
Yep all lines are working. By the time I get to work there are just thin lines defrosted. Every other car would have all the frost gone by then.
 

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There might be a bad connection on one, or both sides, of the window, or elsewhere.

The 2002 rear defroster circuit makes use of a relay that could be bad, and a condensor, which could also be faulty.

If you have a digital multi-meter, start by measuring the voltage on the grid at both ends. One side goes to ground, so the voltage on that side should be low. The other other end of the grid lines goes to 12 V (battery/alternator voltage) from the relay. It should be close to 12 V when the engine is running at 1000 rpm or more. If it's far less, then there's a supply problem. Further trouble shooting will be required, including finding and testing the relay, and the same for the condenser. The relay is located next to the in-cabin fuse panel to the left of the steering column. I'm not sure where the condenser is located.
 

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2002 VDC Outback sedan
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173 Posts
Discussion Starter · #7 ·
Thanks for the tip, yes i do have a digital meter. Somewhere.

So when I put one probe on the grid, where do I put the other? frame of the car/ground?
 

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'14 Subi OBW, '18 Subi Forester
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There is precious little data in my copy of the service manual, like what grid resistance should be, value of that capacitor, etc.

As Plain OM suggested, start at the rear grid terminals. One side should be 13+ v with the engine running with reference to ground (one probe on the terminal, one on a body ground). If you get less than 13, you might have a resistive connection somewhere, a bad relay, or a leakage in that capacitor.

The other terminal should be at ground, so ideally you should get Zero volts between that terminal and the body. If you get a voltage, then you might not have a solid chassis ground. Change to the ohmeter setting and probe between the ground terminal and body ground and see if you get a resistance.

Lastly, we need to consider the current thru the grid, but we'll hold that until you come back with some voltage numbers.
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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could be the parts of the harness that flexes at the top of the hatch has some broken wires. After turning the defogger on for a while, maybe open the hatch and feel if the boot over the wires is warm?
 

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'69 Chevy El Camino, '01 Subaru Outback, '03 Porsche 911
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How can I troubleshoot the defogger on my '01 OBW?

The top half of the element defrosts ice just fine and the bottom half does nothing. Zero, zip, nada.

Can these things be replaced, or only "patched"?
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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as mentioned above, there are repair kits. best if you can physically locate where some cargo has cut thru a line but, there are troubleshooting techniques that might help.

there may even be some youtube videos of how to do it.
 

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Meh.
I has wagons.
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12,372 Posts
Probably has a broken line. Inspect closely, can usually see damage without needing a multimeter.
 

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2018 2.5i Limited; "Wanderlust II"
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Can these things be replaced, or only "patched"?
These grids are "painted" on during manufacture. The only way to replace a bad grid is to replace the entire back glass. The repair kits (which amount to electrically-conductive nail polish) work well enough, but they're a monster PITA to get factory-like results with... You'll quickly become a regular Rembrandt of masking tape.

Call your local auto glass shop; every so often you find one that has a heater-grid repair service. It won't be cheap, but it'll probably be worth the price.
 
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