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96 ford Expedition
If you need more info for this question just let me know.I hate the auto shutoff on the rear defroster. I turn it on when I start my truck and it turns off before it even starts heating up.
I was thinking about rewiring it to a toggle switch, so that it stays on till I turn it off.
Q. is there any “donts” that I need to know of about doing this? exp: might melt something? Or it wont work cause…?
Thank you for your opinions.
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Is the defroster staying on for the normal 10-15 minutes and turning off or turning off very quickly? Most cars are designed to let the defroster go for about 15 minutes and then turn off. I would advise against wiring it up to a separate switch, the defroster can draw a lot of power and if you forget to turn it off can drain your battery. I believe the defroster is on a timer to avoid excessive power draw as well as to avoid anything being damaged by running constantly.
I remember when I was having a hanging furnace installed in the shop. One of the installers said we’ll put the thermostat over here. I said I don’t need a thermostat, if it gets too hot I’ll turn it off. Well, that thermostat came in handy many times when I forgot.
So, I suggest replacing the timer if malfunctioning.
The timer is fine it turns off when it should. It’s just living in northern Michigan we get a lot of snow and at times can have ice build up on the vehicle. I’m just tired of turning it on when I start the truck and when I go to leave it did not even do anything to the rear window.
About draining the battery: I was going to have the switch hooked up in a way so that even if I did leave the switch on when I turn off the truck it will have no power to run.
But if you guys still advise against it then I’ll follow the better judgement.I have two cars, both with the electric grid on the rear window. The defroster on one car will knock off an inch of ice while the defroster on the other is only good for clearing a fogged up window. I suppose the the defroster on the latter car is maybe defective, I’ve never checked. Probably the way to tell is by replacing the glass (expensive) so I will continue with the scraper as I do now.
So, just saying, the problem could be with heat output.
Proceed with caution. There’s a reason they put it on a timer. One reason may be that something may be damaged if it’s left on all the time. Something could melt besides the ice. Granted, electrical loads also effect fuel economy so that might also be the reason.
If you’re going to wire it up separately. Wire it to something ignition hot. Meaning it only gets power with the ignition in the ON position. This will prevent draining the battery if you or someone else leaves it on. Look in the fuse box to see if they have a ‘tab’ for this. I cover this in my fog light install video. In fact, you can wire it up in a very similar way.
Also, wire it up through a relay. If not, you’ll burn up the switch. High amp circuits like defrosters need to run through a relay. If not, switches burn up.
Good luck and keep us updated.
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