Wow, so glad to see this thread. I've been searching on and off for a week now for a solution to this problem. Should have just made a post rofl, will be fixing this as soon as I get off work today.
So replacing the circuit breaker with a fuse DOES NOT, repeat... DOES NOT mess with the rear defroster timing itself to go off? I would really like to not have to pay attention to whether the thing has been on for 10 minutes or 30...
Replacing the circuit breaker with a fuse should have no effect on this timing if the timer relay is working properly. All the fuse does is prevent the circuit from shutting off prematurely because of circuit breaker overheating (a common problem).
__________________ White 2000 Trans Am
usual bolt-ons and some appearance/convenience mods
okay so i think i'm having a problem with my defrost switch too. i put the rear defrost on and usually it turns itself off like everyone was saying, but today it didn't and i didn't really think about it until it started smoking and i couldn't turn it off. How can i fix this? Should i just replace that fuse?
okay so i think i'm having a problem with my defrost switch too. i put the rear defrost on and usually it turns itself off like everyone was saying, but today it didn't and i didn't really think about it until it started smoking and i couldn't turn it off. How can i fix this? Should i just replace that fuse?
You should probably replace the circuit breaker only because it should have tripped before anything started smoking. It is not the cause of this problem. I suspect your defogger timer relay is bad and is failing to timeout as it should.
__________________ White 2000 Trans Am
usual bolt-ons and some appearance/convenience mods
yea after i looked at it a little more after i got back from school, and read a little more about it, i think you're right it probably is the timer for the defogger. Where can i get one at? And is there a relay and a timer or is it just one thing? where is that relay and how can i get to it? is it just that little box thing right behind the button?
I'm afraid you're not going to like this answer...
According to my parts manual, the relay/timer is a non-serviceable part. As far as GM is concerned, you have to buy the whole HVAC panel (#1 in the diagram) to get the relay (part number 16216462, $231 at the dealer - about half that online).
The relay is #10 in the diagram.
You may want to confirm with your dealer that it's not available separately and then consider looking in some junk yards.
__________________ White 2000 Trans Am
usual bolt-ons and some appearance/convenience mods
o that kinda sucks... i put that fuse back in and tried to see if the rear frost would still be stuck on but it actually is stuck off it won't turn back on. so for now i think i'm just going to not worry about it cuz i only got another week or two of driving it for the year
but i'll check into it and see if i can somehow find just that relay but worst case scenario i'll just get a whole new hvac thing like u said. thanks for all your help, i'm not gonna lie as soon as i saw that smoke i was freaking out but luckily it didn't end up being too serious
FYI - I took apart my circuit breaker today and it looked like someone had dipped in to the bowels of hell. (It had been through a bit of thermal cycling.)
I read up on the breakers vs. fuses and according to Bussman/Cooper, the fuses are faster acting than the breakers. I assume that for the defroster, this is only an issue when one starts up the defroster and moves the seats at the same time. Any thoughts?
FYI - I took apart my circuit breaker today and it looked like someone had dipped in to the bowels of hell. (It had been through a bit of thermal cycling.)
I read up on the breakers vs. fuses and according to Bussman/Cooper, the fuses are faster acting than the breakers. I assume that for the defroster, this is only an issue when one starts up the defroster and moves the seats at the same time. Any thoughts?
Like everyone said, circuit breakers over time begin to wear, and it takes less and less current for them to 'break' or open. So lets say it's a 30amp, at this stage, it might only take 15-18 amps for it to open, but it's not linear since as the circuit breaker heats up from current, the amount of current to trip it, will decrease as well. So turning on your defroster pulls 12-15 amps lets say, which the circuit breaker is fine with, until it starts to heat up, and then moving your seat is enough for it to trip.
I've had this problem, but always forget to pick up a new breaker when I'm out. Knowing now that I can just replace it with a fuse is a plus to me. Mine would reset after I turned off the car and let it cool, so who cares if that means having to open the door and replace a 30 cent fuse every year or so.
Like everyone said, circuit breakers over time begin to wear, and it takes less and less current for them to 'break' or open. So lets say it's a 30amp, at this stage, it might only take 15-18 amps for it to open, but it's not linear since as the circuit breaker heats up from current, the amount of current to trip it, will decrease as well. So turning on your defroster pulls 12-15 amps lets say, which the circuit breaker is fine with, until it starts to heat up, and then moving your seat is enough for it to trip.
I've had this problem, but always forget to pick up a new breaker when I'm out. Knowing now that I can just replace it with a fuse is a plus to me. Mine would reset after I turned off the car and let it cool, so who cares if that means having to open the door and replace a 30 cent fuse every year or so.
Right - but if the fuses are fast acting, wouldn't they be more likely to blow from an initial power spike than a new (good condition) circuit breaker? I'm assuming that those power spikes happen - otherwise; why wouldn't GM have put a fuse in there the first place?
I replaced the 30amp circuit breaker with a NEW 30amp circuit breaker and not only did it NOT fix the problem, but the defroster stays on for an even shorter amount of time...
What happens with a fuse? Do you have any tint or other material over the defroster wires on the glass?
Haven't tried a fuse yet. Does a standard size 30amp fuse fit in the slot? I will try that tomorrow when I have a moment. I do have some tint on the glass. Came with the car from the original owner.
I replaced the 30amp circuit breaker with a NEW 30amp circuit breaker and not only did it NOT fix the problem, but the defroster stays on for an even shorter amount of time...
