Hey there. I am new, so don't be too hard on me. My ac went out recently. The display on thermostat is still on, but that is because the batteries are brand new. I checked the circuit breaker and that seems fine. The power switch on the furnace is on as well. So, after reading a bit online, I took the cover off the thermostat to see of the wires had any power. I touched the red to the yellow and the ac turned on. SO, I figured it was a bad thermostat. I replaced the thermostat and still nothing. So, I tested the wires again, but now the ac wont start at all when I touch the red to the yellow. I don't know the issue is but I worry that I shorted something out. At least I feel the thermostat was actually bad; however, I think I caused a bigger problem. Any help is appreciated.
lennyandgragg1
Ok, so I bought a voltmeter and tested the power input and output on the transformer and got nothing. The red light onthe circuit board is also not on. So, I also tested the power switch to the furnace and there is nothing there either.
I then went outside to the ac unit and push the button down on the contractor and the ac turned on. I looked at the capacitor and it wasn’t bulged as if it was blown.
Although my circuit breaker switch is completely in the on position, is it possible it is no good?
I then went outside to the ac unit and push the button down on the contractor and the ac turned on. I looked at the capacitor and it wasn’t bulged as if it was blown.
Although my circuit breaker switch is completely in the on position, is it possible it is no good?
Sounds like the fuse. Check in your furnace for a car type fuse. Always flip the breaker off when playing with thermostat wires. Not for fear of shock but rather shorts.
I forgot to mention that I also bought fuse tester and the fuse in the furnace is fine. I don’t know if it matters, but the circuit breaker made a a buzzing sound when I flipped it back on. It licked and is in the on position but the entire circuit breaker wiggles a little and is looser than the others. Is that typical. My gut is telling me that the circuit breaker is bad even though it is in the on position and not the halfway position. If this is the case, would something have caused the breaker to go bad or does that just happen with time. It is about 16 years old.
The supply power and the low voltage thermostat power are two separate things.
Check the main power first. After all this is where the T-Stat gets its power.
You need to check for line voltage at the outside condensing unit and inside inside the air handling unit.
If you have no power to the transformer, its probably the board where the xfmr resides along with the relays.
A meter will check voltage and will check fuses. I'm not sure what you bought.
If you're like me, you want cool air this time of year.
I would just call an HVAC guy if you're not up to testing for voltage.
How old is the system?
Check the main power first. After all this is where the T-Stat gets its power.
You need to check for line voltage at the outside condensing unit and inside inside the air handling unit.
If you have no power to the transformer, its probably the board where the xfmr resides along with the relays.
A meter will check voltage and will check fuses. I'm not sure what you bought.
If you're like me, you want cool air this time of year.
I would just call an HVAC guy if you're not up to testing for voltage.
How old is the system?
Thanks. The unit is only two years old which is why I didn’t think there would be anything wrong with it. I tested the fuse with a little fuse testing device that came with the fuses I bought. You basically just touch the contacts to the fuse and it lights up if the fuse is good.
I will have to read up on the things you suggested and get to work. This is an upstairs unit, so fortunately I can sleep downstairs where I stil have cold air. I enjoy learning how to do these things, so I will only call an ac technician if I ultimately can’t figure it out.
I will have to read up on the things you suggested and get to work. This is an upstairs unit, so fortunately I can sleep downstairs where I stil have cold air. I enjoy learning how to do these things, so I will only call an ac technician if I ultimately can’t figure it out.
Lenny. If you click on the other forums here, you will find the HVAC forum. Link below.
I used it when I needed a hard to find board.
I ended up replacing my system, but they may be able to direct you better than any of us.
http://www.diychatroom.com/f17/
Not saying we cannot help you measure voltage because we can. But guys that work on HVAC every day might be a better option for answers.
I used it when I needed a hard to find board.
I ended up replacing my system, but they may be able to direct you better than any of us.
http://www.diychatroom.com/f17/
Not saying we cannot help you measure voltage because we can. But guys that work on HVAC every day might be a better option for answers.
Possible Contactor Issue
I am no expert by any means, so bear with me. The AC wouldn't turn on recently, so I checked the thermostat wires. When I touched the R to the Y, the AC started, so I figured my problem was the thermostat. I replaced thermostat, but AC still didn't work. I took thermostat back off to test wires again, but now the AC wouldn't turn on. I figured I shorted something. The circuit breaker is fine and the fuse in the furnace is also fine. However, when I checked in the furnace, the red LED light was out. I bought a voltmeter and tested the transformer, and there doesn't appear to be any power going in or out of it. I then checked the contactor coil in the outside unit, and if I used the voltmeter correctly, my reading was OL, which I read somewhere means it is bad. Does this sound like I need a new contactor? Would that cause the lack of power to the furnace?
I am no expert by any means, so bear with me. The AC wouldn't turn on recently, so I checked the thermostat wires. When I touched the R to the Y, the AC started, so I figured my problem was the thermostat. I replaced thermostat, but AC still didn't work. I took thermostat back off to test wires again, but now the AC wouldn't turn on. I figured I shorted something. The circuit breaker is fine and the fuse in the furnace is also fine. However, when I checked in the furnace, the red LED light was out. I bought a voltmeter and tested the transformer, and there doesn't appear to be any power going in or out of it. I then checked the contactor coil in the outside unit, and if I used the voltmeter correctly, my reading was OL, which I read somewhere means it is bad. Does this sound like I need a new contactor? Would that cause the lack of power to the furnace?
Thanks, that makes sense. Maybe between the two forums, someone can help me figure this out. I tested the power at the main circuit breaker and it is good. I then checked the coil on the contactor in the AC, and if I measured the continuity correctly, I got a reading of OL, which I read means I need a new contactor. I guess I am wondering if that is the source of the problem. Would that cause there to be no power going to the furnace?
Re: Possible Contactor Issue
If your door is off you won’t have power to your furnace. Your all over the place. Try to determine why your furnace is not working first. Then go back to your ac. I suspect you blew a fuse or transformer as well. But your going to have to measure for volts, not ohms at this point. When you take the door off it kills the 120 volts to furnace. You’ll have to temporarily close that switch. Get power to your transformer. Then power out of your transformer and post back and we can go from there.
Sent from my iPad using Tapatalk
If your door is off you won’t have power to your furnace. Your all over the place. Try to determine why your furnace is not working first. Then go back to your ac. I suspect you blew a fuse or transformer as well. But your going to have to measure for volts, not ohms at this point. When you take the door off it kills the 120 volts to furnace. You’ll have to temporarily close that switch. Get power to your transformer. Then power out of your transformer and post back and we can go from there.
Sent from my iPad using Tapatalk
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