My rear defroster in my car doesn't stay on very long anymore. It used to stay on for a couple minutes, maybe five or so, or long enough to at least un-fog the window. Lately, it only stays on for about two minutes or so, barely long enough to see the lines clear up. The switch doesn't get warm or anything.

The question I have is...do the relays or breakers lose resistance with age? Do any of you electronics guys have any idea what causes this and how to fix it?

 

This is an easy and cheap fix usually..
There's a circuit breaker for it in the dash fuse panel..
What you do is exchange it for a 30 amp fuse..
That usually cures the problem..
It should stay on for about 9 minutes or so..

 

I think I've heard that before, but I always assumed that there was a breaker rather than a fuse for a reason.

Unless somebody says that is a bad idea, I think I may try that...anybody else?

 

The breaker is there probably more for convenience. If you have power seats, it powers them too.

The defogger circuit seems like maybe it draws more power with age. Every time a breaker trips, it gets a little weaker. Still, I tried a new breaker and the defog would not stay on. The fuse seems to be a little more tolerant and I have been using one for several years with no problem. You can tell that it does get hot, though. The plastic on the fuse is a little distorted. The metal shelled breaker will get very hot, too. It will burn your fingers if you try to pull it after the defog has been on. A 30A fuse will provide the same circuit protection as a 30A breaker.

 

Ok, thanks guys. I will try this.

 

It's so easy, what could it hurt?

 

I'll try to remember to check my fuse 'for distortion' etc and post back..
Maybe a 'slow blow' fuse would work better?[not sure they even make one in these type auto fuses though..

 

I just dont wanna burn my car down lol. Although I do realize that the fuse would most likely just pop before any fire would start. I just dont know much about electronics, so I am cautious. I trust you guys though, so it's not a big deal