LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Why won't my rear window defrost stay on longer than 30 secs?

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Old 03-19-2003, 08:49 AM
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Why won't my rear window defrost stay on longer than 30 secs?

As the title says, on the Z, the rear defrost will stay on for maybe 30 seconds and then turns off. I know they are supposed to turn off by themself, but isn't it supposed to stay on for at least 5 minutes?
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Old 03-19-2003, 08:54 AM
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My 96 Z does the same, but my girls 94 TA stays on for awhile. I'd like to know the answer also.
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Old 03-19-2003, 08:55 AM
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It is actually supposed to stay on 10 minutes the first time you turn it on. What has been a quick fix for most people is to replace the 30 amp breaker with a 30 amp fuse. It is an easy and cheap thing to try. For some reason, replacing the breaker does not usually do the trick. Don't ever increase the size of the breaker or fuse.

If you have power seats, see if the seat power has also died after the defog trips off. If so, it is the breaker that is tripping (they are both on the same circuit). Be careful, because the breaker can be very hot if you grab it soon after it has tripped.
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Old 03-19-2003, 08:56 AM
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Shoebox, thanks for the tips. Actually, the seat power DOES work even right after the defroster shuts off.
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Old 03-19-2003, 09:08 AM
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Originally posted by Camarocks
Shoebox, thanks for the tips. Actually, the seat power DOES work even right after the defroster shuts off.
If the breaker is not being thrown, then it may be the switch. The timer is part of it and is replaced as a unit. It would not hurt to check your connections at the rear glass, too.
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Old 03-19-2003, 10:00 AM
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The Z is a convertible and the connection in the rear is always falling off, but when it shuts off the strange thing is that it's still connected.

I'll look into the switch though, is there any way to test it with a test light? If I can find one in a junkyard cheap, then I might just replace it.
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Old 03-19-2003, 10:27 AM
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how do you turn on the rear defroster?? i dont have the switch??
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Old 03-19-2003, 10:33 AM
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You probably don't have the rear defrost option. From what I've read not all Z's do.
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Old 03-19-2003, 10:51 AM
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Originally posted by TMDZ28
how do you turn on the rear defroster?? i dont have the switch??
You would have a rocker switch right below the right side of your instrument cluster. You'd know if you had it, there aren't exactly a lot of buttons in a Z.
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Old 03-19-2003, 11:33 AM
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Changing to a fuse fixed mine... it went from staying on 2-3 minutes to 9 1/2 minutes.. no problems since the change..
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Old 03-19-2003, 01:31 PM
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my friend had a 95 Z and his didnt have the rear defroster option. Never even noticed it till he says, "looks weird without a rear defroster, huh?" i was like...dang..i never noticed it! :-D
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Old 03-19-2003, 05:24 PM
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Thank God for Fog-X!!!


... from the makers of rain-x.
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Old 03-19-2003, 06:04 PM
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went to autozone picked up a 5 fack of 30A fuses and came back home pulled out the breaker and replaced it with the fuse and now the defroster stays on for awhile...not sure how long yet... cuz i havent made a trip longer than liek 4 mins ha but it worked thanks
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Old 03-19-2003, 06:47 PM
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Originally posted by 2CNTRY
Got the same problem.

When your defrost is on for that 30 seconds, does it look like you are getting any heat on the wires back there or not at all? Mine looks like it might throw a jolt or two on the wires but doesn't make a "dent" at all for that short period; we've all seen immediate defrosting on other makes.

me
Yes, it does melt the snow/clear up the fog for the short time that it is on. If I go ahead and replace the breaker with a fuse, is this safe?
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Old 03-19-2003, 06:51 PM
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Originally posted by Camarocks
Yes, it does melt the snow/clear up the fog for the short time that it is on. If I go ahead and replace the breaker with a fuse, is this safe?
Safe as long as you keep the amp rating the same..
Maybe carry an extra fuse or keep the CB in case the fuse happens to pop[ mine hasn't... been about a year since I changed it]
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