A/C & heat don't turn on - home unit

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It's been mild here for the past two weeks so we've not had the A/C on. Today is a bit of a warm day so I wanted to turn the A/C on and noticed that the A/C didn't kick in when it should've based on the way it's programmed. Turned the program off and switched it to A/C mode and set the temp to 75*, no dice. Turned the fan on, and that works just fine. Decided to see if I set it to heat if it would kick the heater on, no dice again. Mind you, when I manually switched to heat or cool, neither a snowflake nor flame appeared on the screen.

Sounds like my thermostat is the problem, thoughts?



IMG_20180915_153825583.jpg
 
Last edited:
Originally Posted by dbias
Check the fuse on the circuit board of the hvac unit.

Fuse looks good and nothing tripped on the breaker. According to my wife, she had it on yesterday for a few hours.
 
Last edited:
Originally Posted by Papa Bear
Thermostat battery ??


Good point -- definitely check the batteries before replacing the thermostat. In my case when we had a similar issue, unfortunately the batteries didn't make a difference and I had to replace the entire unit.
 
Originally Posted by Padawan
Sounds like a faulty thermostat to me.
What does a faulty thermostat sound like?
 
Originally Posted by CT8
Originally Posted by Padawan
Sounds like a faulty thermostat to me.
What does a faulty thermostat sound like?


Bang on it twice with your fist. Then you will instantly become familiar with the sound.
 
Originally Posted by Papa Bear
Thermostat battery ??

I'd definitely check that. Mine exhibited some strange behaviour when the batteries ran down, and there wasn't a low battery warning, either. Things just started to "not work" very well, with AC not kicking on when it should have.
 
I pulled the thermostat and wired the hot to the a/c, heat and fan and all worked accordingly. Thermostat confirmed.

Could've been the batteries, but it's a 12 year old unit and has had quirks over the past two years anyway so I'm just replacing it.

Thanks for the feedback!
 
You can see the low battery indicator on in your picture. I have that exact same thermostat and they are quirky. This time of year they like to kick into a delay mode where it waits before turning on. The flame or snowflake will flash for a few minutes before any thing happens.
 
Originally Posted by Triple_Se7en
Originally Posted by CT8
Originally Posted by Padawan
Sounds like a faulty thermostat to me.
What does a faulty thermostat sound like?


Bang on it twice with your fist. Then you will instantly become familiar with the sound.

lol.gif
 
Originally Posted by jhellwig
You can see the low battery indicator on in your picture. I have that exact same thermostat and they are quirky. This time of year they like to kick into a delay mode where it waits before turning on. The flame or snowflake will flash for a few minutes before any thing happens.


Oh yeah, I've played that flashing indicator game plenty of times. Its the strangest thing but this unit loves eating batteries, or at least acting like it's eating them. I've gone through 4 sets of batteries in 2 years. Fresh ones are good for about a month, then the battery indicator will come on and the unit will die 5 to 6 months later.
 
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