I have a Honda Civic 2010. I turn on the rear window defrost and it only stays on for 15 minutes. I live In Canada and work from my car. 8 hours a day I am having to turn it on every 30 minutes. Is there anything I can do to keep the Rear Defrost on all the time? It's a hassle continuously having to turn it on.

 

I think starting in 2001 the operation of that button goes through the software in the heater / AC control panel. So there'd be no simple mod to make the button stay on longer. You should be able to add a switch to force the relay to stay on though. The reason why it has a timer is it's a considerable strain on the alternator to run it all the time.

 

That could be why the alternator kept going on my old car. What an interesting fact.