3amp fuse popping on circuit board

[thatguy]

As I've mentioned in your other post that you have about this same issue, I suggest you get an experienced technician on site with you to teach you with some hands on training. You would really benefit from that. Your answers and questions are suspiciously homeowner like and is showing a lack of basic troubleshooting skills. Electricity is dangerous and you haven't been able to follow the advice given to you in your other post and that makes me worried. If you start changing parts in the furnace without a proper understanding of what you are doing then you could be endangering the lives and safety of the occupants in that house.


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[pecmsg]

Get the wiring diagram and follow it!

[VTP99]

As I've mentioned in your other post that you have about this same issue, I suggest you get an experienced technician on site with you to teach you with some hands on training. You would really benefit from that. Your answers and questions are suspiciously homeowner like and is showing a lack of basic troubleshooting skills. Electricity is dangerous and you haven't been able to follow the advice given to you in your other post and that makes me worried. If you start changing parts in the furnace without a proper understanding of what you are doing then you could be endangering the lives and safety of the occupants in that house.


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[timebuilder]

Just so the OP understands...

we can't give detailed technical advice on this in the open forums.

[beenthere]

Merged threads. Don't make duplicate threads.

[VTP99]

Merged threads. Don't make duplicate threads.

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[Betabass]

Replace the board, all outputs disconnected and fuse blows.....bad board.

Betabass


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[Anoob]

oops already asked....

[BNME8EZ]

I haven't seen anyone else ask this so here come a 1st grade question. Did 24v power and common get switched on the board? If common on the transformer is grounded and common on the board are grounded and you switch power and common on the board you have direct short.

[digidoggie18]

If you disconnected all control voltage from it then absolutely yes it could be a bad board... Check the mounting of the board and make sure that nothing is touching the metal plate behind it in any way shape or form... Sounds like you have 120v jumping somewhere... can you try reading the voltage through the fuse section? I.e. shut off power, put a new fuse in, attach meter leads to fused section with voltage on and set it to max hold... Click power on and read it? It's not truly necessary to do but I enjoy being thorough and giving a definitive answer to the customer...

[BBeerme]

If the OP had a Short Pro Tool, it would only take a few minutes to figure it out. Had to use mine just this last week, only took a minute to determine it was the compressor contactor. And guess what? I only used the one fuse that was used to replace the bad one, LOL.

https://www.ebay.com/i/173521527155?chn=ps

https://www.youtube.com/watch?v=SZCXbQLgjaI

[BBeerme]

Took me longer to go to the truck to get the Short Pro Tool than it did to find the short.

[VTP99]

Took me longer to go to the truck to get the Short Pro Tool than it did to find the short.

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[BBeerme]

��
[insert thumbs up emoji above]

[11crv]

Everyone should have a short pro tool. Used mine 2 last week.

[rundawg]

Everyone should have a short pro tool. Used mine 2 last week.

Used mine today.

[DOGBOY]

So why doesn't everybody just watch for the large spark when you are jumping from red to the other connections? You can actually see the spark before the tool lights up. Only tool needed is a jumper and I have done it this way for nearly 30 years. I kinda think that the jumper is the real tool here.

[BBeerme]

I guess. If you have a pocket full of fuses.

Then there are the intermittent problems, like with a wire rubbing through on a piece of metal. Just need a whole bunch of fuses.

So why doesn't everybody just watch for the large spark when you are jumping from red to the other connections? You can actually see the spark before the tool lights up. Only tool needed is a jumper and I have done it this way for nearly 30 years. I kinda think that the jumper is the real tool here.

[DOGBOY]

I guess. If you have a pocket full of fuses.

Then there are the intermittent problems, like with a wire rubbing through on a piece of metal. Just need a whole bunch of fuses.

Actually you do not connect the wire and leave it connected as that will short the transformer. I only briefly touch the wire to see if there is a spark. You can actually see it in one of the you tube video's I watched (as I have never heard of a short pro tool). here is a like to it and if ou watch at 2:45 to 2:50 https://www.youtube.com/watch?v=SZCXbQLgjaI you can see the spark. however I am sure you all have seen the spark already.
Now with that said yes there are some shorts that are intermittent and those you actually have to look for, I had 2 this summer that took me over 1 hour to find on the same model different spots but both shorts were in the cooling circuit both going to the economizer and had to pull the top to find them, another only blew the fuse when it was morning and if there was a heavy dew as the wires outside were chaffed in a spot you could not see and the water actually made the path. Don't really see how that tool would have helped then.
Now with all of that said I may blow 1 fuse occasionally as I will jump out the fuse and not keep replacing them. Now I do expect some negative remarks from that last sentence but a transformer will not pop in just 1 or 2 seconds of having a direct short.

[BBeerme]

Don't see why anyone would slam you for doing it old school. After all, there was a time we all had to do that.

The short pro tool just makes things easier.

Sort of like the difference of walking to work, or driving.

Actually you do not connect the wire and leave it connected as that will short the transformer. I only briefly touch the wire to see if there is a spark. You can actually see it in one of the you tube video's I watched (as I have never heard of a short pro tool). here is a like to it and if ou watch at 2:45 to 2:50 https://www.youtube.com/watch?v=SZCXbQLgjaI you can see the spark. however I am sure you all have seen the spark already.
Now with that said yes there are some shorts that are intermittent and those you actually have to look for, I had 2 this summer that took me over 1 hour to find on the same model different spots but both shorts were in the cooling circuit both going to the economizer and had to pull the top to find them, another only blew the fuse when it was morning and if there was a heavy dew as the wires outside were chaffed in a spot you could not see and the water actually made the path. Don't really see how that tool would have helped then.
Now with all of that said I may blow 1 fuse occasionally as I will jump out the fuse and not keep replacing them. Now I do expect some negative remarks from that last sentence but a transformer will not pop in just 1 or 2 seconds of having a direct short.