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roadwreck

Probie-one, PE
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Earlier in the week the thermostat on one of my homes HVAC units started acting squirrelly. I walked into my living room Monday morning to find the room at a brisk 60 degrees, even though the thermostat was set to keep the room at 80. The thermostat thought the temperature in the room was 84, meaning the A/C had been running all night. I turned the A/C in that part of the house off and went to work. On my way home I stopped by the hardware store and picked up a new thermostat.

I didn't get around to replacing the thermostat until last night. Before disconnecting the old one I turned the system off at the unit then flipped the breakers in the central panel in the garage. Then I replaced the old thermostat with the new one, turned the breakers back on and turned the thermostat on...

...nothing. At first I thought maybe I had a bad connection in the new thermostat. So I shut everything down again, and checked the connections in the thermostat and turned everything on again. Still nothing. At this point I thought maybe the new thermostat I bought was faulty, so I set about uninstalling it and reinstalling the old one. So I shut everything down, disconnected the new one put the old one back. Turned everything on and...

...nothing. Neither thermostat indicates that their is a problem. After more sleuthing I found that the Furnace/Blower doesn't seem to have power even when the breakers for it are on. Normally their is a green flashing light on the front of the unit to indicate it is operational. Now their is no light, only a faint buzzing noise coming from the unit when it is supplied with power. I've tried turning off and on any breaker or switch I can find for the HVAC at this point, nothing seems to getting this thing going again. Is anyone aware of a reset switch on the system that I need to trip in order to get this thing going again? I'm about to throw in the towel and call in the professionals. I'd rather not have to do that if they are just going to show up, flip a switch then hand me a bill for a couple hundred bucks. :(

Any thoughts or suggestions would be appreciated.

 
can't offer anythign more than moral support. If changing the thermo didn't work we would have called for help.

 
can't offer anythign more than moral support. If changing the thermo didn't work we would have called for help.
changing the thermostat caused more problems, at least the system was running (and working well) with the old thermostat. The only problem I had with the old thermostat was it was giving faulty temperature readings. Now the whole system won't run. :(

Good thing I have more than one system for the house, or it would have made for a hot & sweaty night last night, and not in a good way.

 
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I have a feeling the thermostat wasn't the problem. I'm betting the contactor on the outside until was stuck in the on position. I've had that happen before. The funny thing is, I have pulled the breakers and when I reinstalled them, I got the no-run condition.

Of couse, i called the AC guys, and the AC was running perfect when they tried it. None of us could figure it out, but, hey, it is still running.

 
I have a feeling the thermostat wasn't the problem. I'm betting the contactor on the outside until was stuck in the on position.
I dunno, if that were the case then the A/C would run no matter what the thermostat said right? I could get the the A/C to cut out without turning the whole system off by simply revising what I wanted my old (faulty?) thermostat set at. The old thermostat was showing that it thought the temperature inside the house was 84 degrees, even though it was close to 60. Since the thermostat thought it was 84 and it was set to cool to 80, the A/C was running, even though it was actually 60 degrees in the house. If I bumped the desired room temperature of the old thermostat up to read 85, the A/C cut out. So the old thermostat still worked, it's temperature readings were just off. I could have left the old thermostat in place and just figured out some sort of conversion for what the temperature the thermostat was reading vs. what temperature I actually wanted the room to be. The whole system was working normally other then that before I disconnected the old thermostat. Now it doesn't work at all. :(

 
I have a feeling the thermostat wasn't the problem. I'm betting the contactor on the outside until was stuck in the on position.
I dunno, if that were the case then the A/C would run no matter what the thermostat said right? I could get the the A/C to cut out without turning the whole system off by simply revising what I wanted my old (faulty?) thermostat set at. The old thermostat was showing that it thought the temperature inside the house was 84 degrees, even though it was close to 60. Since the thermostat thought it was 84 and it was set to cool to 80, the A/C was running, even though it was actually 60 degrees in the house. If I bumped the desired room temperature of the old thermostat up to read 85, the A/C cut out. So the old thermostat still worked, it's temperature readings were just off. I could have left the old thermostat in place and just figured out some sort of conversion for what the temperature the thermostat was reading vs. what temperature I actually wanted the room to be. The whole system was working normally other then that before I disconnected the old thermostat. Now it doesn't work at all. :(
Oh, OK. I thought it was running no matter what. Sorry.

I'd futz around with the cnnections. Last I messed with one, there were about six different ways to wire it, based on the way the HVAC was configured and what it ran on.

 
Oh, OK. I thought it was running no matter what. Sorry.
I'd futz around with the cnnections. Last I messed with one, there were about six different ways to wire it, based on the way the HVAC was configured and what it ran on.
In a way I tried that too. I tried setting up the new thermostat twice before deciding (incorrectly it seems) that it was at fault, so I went back and hooked up the old thermostat which I "knew" worked and I knew how to connect. It wasn't until I got the old thermostat up and it had the same problem as the new thermostat that I decided something else was not right. I disconnected and reconnected everything in the old thermostat again just to be sure I didn't have any faulty connections and when that didn't change anything I took the whole thing down again and reinstalled the new thermostat again. Still no signs of life from the HVAC system.

I'm pretty certain I've set the thermostats up correctly. The fact that the blinking green status light on the furnace, which usually indicates the system is on, is off completely now seems to indicate that the furnace isn't getting power anymore. I find it hard to believe that has anything to do with replacing the thermostat, I assume it has something to do with me cutting the power to the furnace from the breaker box. Now I can't get the stupid thing to turn on again. I don't know if that is a problem that can be caused by the thermostat connections or if there is a reset switch somewhere else on the unit that needs to be flipped. I'm just annoyed that before I started this repair the system was working, even if the thermostat readings weren't right. Now the whole system is off and won't come back on. :(

 
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cool! 50 cents is much better than the hundred or so for a service call.
I'll say! Thanks again for the link, I wouldn't have known to replace that on my own.
google searches have saved us lots of money. most of the time someone else has had the same problem and either posted a question or made a you tube video on how they fixed.

 
cool! 50 cents is much better than the hundred or so for a service call.
I'll say! Thanks again for the link, I wouldn't have known to replace that on my own.
google searches have saved us lots of money. most of the time someone else has had the same problem and either posted a question or made a you tube video on how they fixed.

That's how I learned to hem jeans while keeping the factory hem appearance! And shortly following, I also Googled "how to thread a bobbin", followed again by "how to use a sewing machine."

 
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