Stereo & Electronics - Defroster switch...

Can you make the defroster for the rear hatch glass stay on longer? I don't know if something's wrong with it, but when I turn it on, I feel like it stays on for a minute and a 1/2 and then turns off (back glass isn't totally defrosted) and then I have to wait about 7-8 minutes before I can turn it back on. In this time frame that it won't turn back on, if I hit the rear defroster button, it just clicks, almost as if it's preventing itself from turning on to keep it from over heating or something. It's done this ever since I've had the car, but I wasn't the first owner so I'm not sure if this is normal or if there's an issue.

Thanks for any help.

Adam

Just replace the relay in the fuse panel for the defroster with a standard 30 amp fuse. Its a very common problem easily fixed.

http://www.fullthrottlev6.com/forums/attachment.php?attachmentid=2847&d=1255503997

Or you can replace the defroster relay to get the stock behavior. (When they go bad, they shut the circuit off prematurely.)

Having the same issue, will try these out and see what I get.

Or you can replace the defroster relay to get the stock behavior. (When they go bad, they shut the circuit off prematurely.)

Is this located under the dash on the driver's side?

I think it is in with the HVAC Controls

Replacing the circuit breaker (it's not a relay) in the dash fuse panel with a normal 30 amp fuse (or a new 30 amp circuit breaker if you want to spend the money) will fix the problem. The factory circuit breaker tends to overheat and break the circuit when it gets old. There is no need to replace any other parts.

So just a regular 30 amp fuse will work as well? I know the original one is a circuit breaker. Mine has been crapping out lately after only about 30 seconds of being on and it gets VERY hot to the touch while the defroster is on.

Replacing the circuit breaker (it's not a relay) in the dash fuse panel with a normal 30 amp fuse (or a new 30 amp circuit breaker if you want to spend the money) will fix the problem. The factory circuit breaker tends to overheat and break the circuit when it gets old. There is no need to replace any other parts.

Just pop a 30 amp fuse in there? If that's what's in there to begin with, won't this problem just come back?

Well, went and put a 30 amp fuse in there and it works beautiful. Apparently with the circuit breaker it gets old and jsut allows it to cycle for like 30 seconds. It went for 5 minutes and then I just gave up waiting for it to turn off. :lol:

BUMP!

would I have to take the HVAC panel off to get to that fuse? How difficult is that?

sweet now i can fix mine wondering why this didnt work right

BUMP!

would I have to take the HVAC panel off to get to that fuse? How difficult is that?

The fuse is in your driver side fuse panel. There is NO fuse/breaker in the HVAC controls.

Just pop a 30 amp fuse in there? If that's what's in there to begin with, won't this problem just come back?
No, the factory circuit breaker works by breaking the circuit when too much current flows through it. The advantage is that when it cools, it reconnects the circuit so you don't have to replace it like an ordinary fuse. The problem is that the circuit breakers tend to overheat under normal load as they get older so they break the circuit even though there is nothing wrong. You can put in a new circuit breaker or a fuse but a circuit breaker costs more and will wear out again eventually.

BUMP!

would I have to take the HVAC panel off to get to that fuse? How difficult is that?No, the circuit breaker is in the fuse panel on the left end of the dash. It has two blade pins just like an ATO/ATC plastic fuse so you can replace it with a fuse of the same rating (30 amps).

No, the factory circuit breaker works by breaking the circuit when too much current flows through it. The advantage is that when it cools, it reconnects the circuit so you don't have to replace it like an ordinary fuse. The problem is that the circuit breakers tend to overheat under normal load as they get older so they break the circuit even though there is nothing wrong. You can put in a new circuit breaker or a fuse but a circuit breaker costs more and will wear out again eventually.



So long story short, replace the circuit breaker with a 30 amp fuse and be done with it...? I guess I didn't realize they fit into the same slots.

Wrong info. Was told the wrong thing.

Man I'm glad I'm not the only one having this retarded issue. I have been cussing this thing for the past 2yrs wondering why the hell it was kickin off so fast & wouldn't turn right back on if the window wasnt done yet.

No, the factory circuit breaker works by breaking the circuit when too much current flows through it. The advantage is that when it cools, it reconnects the circuit so you don't have to replace it like an ordinary fuse. The problem is that the circuit breakers tend to overheat under normal load as they get older so they break the circuit even though there is nothing wrong. You can put in a new circuit breaker or a fuse but a circuit breaker costs more and will wear out again eventually.

I suppose that the defroster timer relay at the HVAC control panel is just purely a timer then? (I've had older GM cars where the timer relay would also overheat and cut the circut off.)

I suppose that the defroster timer relay at the HVAC control panel is just purely a timer then? (I've had older GM cars where the timer relay would also overheat and cut the circut off.)The defogger timer relay serves the dual function of routing high current based on a low current trigger (normal relay function) and limiting the time that the current flows (timer function). The defogger runs for about 10 minutes the first time it is activated and for 5 minute periods for each subsequent use until reset by cycling the ignition off. 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).

BTW, as you mentioned, older cars had timer relays that were thermal like a thermostat - our cars have solid state electronic timer relays.

And, in case nobody has noticed, when the circuit breaker overheats and the defogger isn't working the driver's power seat is dead also. It works again when the breaker cools down.

replace the breaker with a fuse, as mentioned above, and say goodbye to the problem.

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...

I don't know how I could have been clearer...
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).

Just wanted to be clear as a few posts following your's made it a bit confusing is all... sorry

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.

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).

http://www.fl1v.org/ls1/hvac_panel.png

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.

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?

Mine has been fine. Ive used it and moved my seat and nothing has happened.

UPDATE:

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...

Any suggestions?

What happens with a fuse? Do you have any tint or other material over the defroster wires on the glass?

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.

Try the fuse!!! I have tint (5%) and it works perfectly now. Before it would only come on for about 35 seconds and then turn off.

Standard sized 30amp fuse? nothing special? I'll try this morning and let you know

Standard sized 30amp fuse? nothing special? I'll try this morning and let you know

Yes - nothing special.

UPDATE:

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...

Any suggestions?

suggestions?????? yeah, read the thread.




put a fuse in and be done.

Well, put the fuse in and it seems to be working fine. Timed it and it stayed on for exactly 10 minutes. I still don't understand why the circuit breaker doesn't work.... Is it essentially the same technology?

You're right - there is no reason a new circuit breaker shouldn't work just as well as a fuse. As long as they both pass the required current without blowing, there should be no difference in operation. It is possible that the new circuit breaker you bought is defective.

I'm wondering if the tint could conduct additional current through the defroster. The fuses look like they actually blow at a higher amperage (just over 40A for a 30A fuse) http://www.cooperbussmann.com/pdf/56fdf5fe-1208-43b4-bda9-828673caf2e6.pdf than the breakers, which drop their trip point as the temperature increases. http://www.cooperbussmann.com/pdf/d698bc45-120e-47ae-9375-ebf1cda0ad62.pdf

Either way, the fuses look to be more stout as they blow at higher power at higher temperatures.

I'm wondering if the tint could conduct additional current through the defroster. The fuses look like they actually blow at a higher amperage (just over 40A for a 30A fuse) http://www.cooperbussmann.com/pdf/56fdf5fe-1208-43b4-bda9-828673caf2e6.pdf than the breakers, which drop their trip point as the temperature increases. http://www.cooperbussmann.com/pdf/d698bc45-120e-47ae-9375-ebf1cda0ad62.pdf

Either way, the fuses look to be more stout as they blow at higher power at higher temperatures.

Which leads me to believe that circuit breakers are safer in the sense that they keep things from frying while the fuse "lasts" longer, although dangerously...

Glad I just saw this post, my defroster in the back has been acting screwy recently, randomly kicking off after only a min or two, and not turning back on. Now I know what to do about it :)

Mine defroster work fine. But at Idle turn it on the amp gauge drops to a little less then 13 some times to 13. Turn it back off it goes back to normal I geuss. Some times going down the road my light dim and go back to normal.

This is great info! I have been ignoring the same issue for a couple of years now! Thanks LS1tech!

This is great info! I have been ignoring the same issue for a couple of years now! Thanks LS1tech!

me too lol, i just thought thats how it worked.