Have HVAC Questions? Ask an HVAC Expert for Answers
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?
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.
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?
That is possible but we have not determined this yet.
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.
On the B/C terminal?
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?
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.
Wait a second
Hang on, Do you see a model on thermostat?
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.
Yes that is it.
Now lets call for heat and see if it blows or heat works
Still have normal status code?
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.
Ignore those last links
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.
To rate answer, please select one of the stars on the page.