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leaving the rear defroster on constantly

up vote 14 down vote favorite

So the front defroster of my vehicle seems to work by blowing air up at the window. The rear defroster seems to work having a bunch of wires that run the length of the window. My question is... would there be any harm in just leaving the rear defroster on constantly?

2 Answers

up vote 4 down vote accept

If you leave it on while the engine is not running, then you will quickly flatten the battery. Other than that, it will do no harm leaving it on.

It will of course cause a small increase in fuel consumption.

up vote 3 down vote

I've seen GMs that burn up/melt the passenger side relay block/trunk fuse panel. Due to the rear defroster being run constantly.


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leaving the rear defroster on constantly

up vote 14 down vote

So the front defroster of my vehicle seems to work by blowing air up at the window. The rear defroster seems to work having a bunch of wires that run the length of the window. My question is... would there be any harm in just leaving the rear defroster on constantly?


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up vote 9 down vote

If you leave it on while the engine is not running, then you will quickly flatten the battery. Other than that, it will do no harm leaving it on.

It will of course cause a small increase in fuel consumption.

edit

@neubert If the ignition is on, the heater will work, even if the engine is not running. - HandyHowie Jan 21 at 18:38

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