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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Honeywell thermostat that was working fine until about

Customer Question

I have a Honeywell thermostat that was working fine until about an hour ago. The air will not turn on. The inside temperature has reached 81 degrees but when I turn it to 73 or 75, it does not click on; it just says "hold". I've tried turning off and on and changing batteries but nothing is making it turn on
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.
Hello. My name is ***** ***** I'll do my best to help. Let's get started and see what we can do.Will fan come on if you select fan ON rather than auto? Ad do you have a volt meter for troubleshooting?
Customer: replied 1 year ago.
no, nothing comes on - I don't know what a volt meter is
Customer: replied 1 year ago.
I got your response late because it didn't show up immediately - are you still there?
Expert:  airheatman replied 1 year ago.
I am here but can not take phone call right now.A volt meter is a tool for troubleshooting to see where we are and are not getting power. Can you do some hands on like removing low voltage wires and touching them together?
Customer: replied 1 year ago.
I am not an electrician and have no idea what you are talking about when you refer to "low voltage wires" - there does not seem to be any wires attached to the thermostat
Customer: replied 1 year ago.
Isn't there a way to generally troubleshoot from the readings on the thermostat?
Expert:  airheatman replied 1 year ago.
There are wires attached to the thermostat.They come through the wall from behind the thermostat. You might be better off calling in a technician if you have no idea what you are doing and think you will have a hard time following instructions or have no meter for troubleshooting.If you can follow some steps, there are a couple of things we can check and if we get to point we have to have meter you can get a inexpensive one at Walmart.
Customer: replied 1 year ago.
Isn't the point of contacting you as an expert to basically say what it could be?
Customer: replied 1 year ago.
can you troubleshoot given the basic info -
Expert:  airheatman replied 1 year ago.
My hopes are to help you actually get it going, not just give you a list of things that it "could" be.
If all you are looking for is the list, the most common causes will be:
1. Bad transformer in furnace
2.Blown auto type fuse in furnace
3. Bad control board in furnace.
4.Defective thermostat.
JUst looking at the numbers on thermostat will not help in troubleshooting.If a tech comes there, just like me guiding you, the first step in troubleshooting is to see if we are getting 24 volts to the thermostat from the furnace.Your display may be operating on battery power. If you can remove the cover on thermostat you will see the thermostat wires from furnace. I can guide you in a couple of steps without a meter.
Customer: replied 1 year ago.
I took the cover off the thermostat but it is placed on the wall so tight that I cannot get it completely off. I do see the wires, but unfortunately cannot reach them easily. It sounds like the air conditioner starts to hum as if it is going to start but never completely clicks on; it did go from "hold" to "temporary". I am wondering if it just go so hot inside that it will take awhile to "click on"
Expert:  airheatman replied 1 year ago.
I have to leave for a bit, so I will open to other experts and check in s soon as I get back.
Expert:  airheatman replied 1 year ago.
OK I am back. Does fan on indoor unit, outdoor unit or anything come on?

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