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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8063
Experience:  Furnace, A/C and heat pump specialist.
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My thane gas furnace circuit board five amp fuse continues

Customer Question

my thane gas furnace circuit board five amp fuse continues to blow
Submitted: 7 months ago.
Category: HVAC
Expert:  airheatman replied 7 months ago.

If fuse is blowing we have a dead short in 24v control circuit somewhere.It may take several fuses to troubleshoot.Do you have fuses and do you want to troubleshoot this yourself?

Customer: replied 7 months ago.
I would like to try myself
Customer: replied 7 months ago.
What do I need todo ?
Expert:  airheatman replied 7 months ago.

We will start by turning power off.Replace fuse. Disconnect all of the thermostat wires at furnace control board. Then power back on and see if fuse blows. If it does, short is in control board.If not we will go from there.

Customer: replied 7 months ago.
I did and fuse did not blow the green led was flashing with no red led on
Expert:  airheatman replied 7 months ago.

I am not showing a green, only a red and yellow, board may have been replaced at some time. Is there a pattern to the flash?

Does board look different from this?

Customer: replied 7 months ago.
Do I need a new thermostat
Expert:  airheatman replied 7 months ago.

That is possible but we have not determined this yet.

Customer: replied 7 months ago.
Normal flashing green like I think it's good
Customer: replied 7 months ago.
It's normal no call for heat
Expert:  airheatman replied 7 months ago.

OK looks like that is a re[placement board. With thermostat in OFF system and Fan AUTO, reconnect one wire at a time, turning power back on between each and see if fuse blows.

Customer: replied 7 months ago.
Ok
Expert:  airheatman replied 7 months ago.

Standing by

Customer: replied 7 months ago.
The red and blue wire tripped fuse
Expert:  airheatman replied 7 months ago.

On the B/C terminal?

Customer: replied 7 months ago.
Expert:  airheatman replied 7 months ago.

OK I have a couple of questions.

1.Tell me what terminals are used at thermostat and what color wires to each

2.Did that loose yellow come rom Y?

3.How many wires are going to outdoor unit , what color are they and where do the attach at furnace?

Customer: replied 7 months ago.
B,o,g,y,w,r,rc wire color to terminal blue= b green=g yellow = y white =w red = r and there's a bridge from R-Rc. The lose yellow came from y and so did the lose white wire I do t no how to get the answer to question 3
Expert:  airheatman replied 7 months ago.

OK next do this.Turn power off and replace fuse. Remove the Red wire from the B/C, leaving blue attacted to B/C. Turn power on and see if fuse blows.

Expert:  airheatman replied 7 months ago.

Wait a second

Customer: replied 7 months ago.
Ok and do I put all wires on but the red on bc
Expert:  airheatman replied 7 months ago.

Hang on, Do you see a model on thermostat?

Expert:  airheatman replied 7 months ago.

Get that Blue wire off of B/C and disconnect it from B at thermostat.That is what is blowing fuse most likely.

On this thermostat B is not 'COMMON".

Remove the blue wire from furnace and thermostat.Reconnect everything else as it was and lets see if that solves the problem.

Customer: replied 7 months ago.
RTH111B1024 I think that's it
Expert:  airheatman replied 7 months ago.

Yes that is it.

Get that Blue wire off of B/C and disconnect it from B at thermostat.That is what is blowing fuse most likely.

On this thermostat B is not 'COMMON".

Remove the blue wire from furnace and thermostat.Reconnect everything else as it was and lets see if that solves the problem.

Customer: replied 7 months ago.
Ok doing so now
Expert:  airheatman replied 7 months ago.

Standing by

Customer: replied 7 months ago.
Fuse is still good flashing green for no call for heat
Expert:  airheatman replied 7 months ago.

Now lets call for heat and see if it blows or heat works

Customer: replied 7 months ago.
Called for heat the blower is not kicking on and I'm not sure if it's igniting
Expert:  airheatman replied 7 months ago.

Still have normal status code?

Customer: replied 7 months ago.
Blower just kicked on and we got heat everything looks and sounds normal
Expert:  airheatman replied 7 months ago.

Excellent.That blue wire was the problem sounds like. B is common on some thermostats but not on yours. Try ac and fan before we close.

Expert:  airheatman replied 7 months ago.

Ignore those last links

Customer: replied 7 months ago.
Everything seems to check out
Expert:  airheatman replied 7 months ago.

Great news.

If you have further questions, please let me know.

Thanks for letting me work with you.If my answer has been polite, professional,and thorough, please click one of the ratings before you go. If you still need help let me know!.Expert is not paid for assisting you until you rate answer.Feel free to follow up for 30 days at no additional cost. Bonus always appreciated if you feel justified.

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