My a/c kicked off

[Marthe48]

The thermostat readout was blank, so I replaced the batteries. The screen lit up, and said the temp was 82. The fan came on, but the Auto set didn't work. I went to the basement and checked the breaker boxes, but none of them were tripped. I don't know much about the HVAC. I don't know if it has its own box somewhere away from the main boxes I have. I realized as I was looking that if the circuit tripped, the fan wouldn't have come on. I came back upstairs, and tried the thermostat again and the A/C came on and is working now. I had it set at 74 since June 24. I've turned it up to 81 to baby it. I'll try turning it down until I go to bed. None of the other electrical devises kicked off.

Is it possible that the system shut off because the thermostat needed batteries? And it took the system a minute or 2 to kick on? The whole unit was new in 2008 or so.

I'll call for a check up on Monday, but pretty sure I'll have a wait.

Any opinions on what might have caused it to kick off? Thank you!

[SheltieLover]

1. What brand & type is is & how old?

[Marthe48]

3. It's a Carrier

We got it installed about 2008 or 2009.

[SheltieLover]

2. Depending upon how it is wired, the batteries could shut it down

If they wired it so thermost is a relay, then it would cause it.

If thermostat is only powered by the batteries rather than the unit itself, in other words, bad batteries will shut it down.

Per gs, the hvac / IT guy.

Good luck!

[Marthe48]

4. Thank you!

The thermostat goes thru batteries pretty fast, esp. if I'm flipping the setting up and down. I had to change them earlier this year, but had warning they were failing. The thermostat won't switch from one mode to another and I know it's time. I've been leaving the setting alone and changing my clothes as needed I have my own thermostat, as so many of us do

Thank you. The temp is coming down and the system sounds normal.

[SheltieLover]

6. Yw!

Yay!

[Kali]

5. what caused it?

a heat wave and a holiday weekend, same with veterinary emergencies.




(sorry)

[SheltieLover]

7. Dead batteries in thermostat

Due to inferior wiring design.

[Kali]

13. I was making a funny

or at least trying

[SheltieLover]

15. Sorry

I thought you were curious.

[SheltieLover]

8. Depdnding upon the install config, rewiring thermostat

To get power from the unit, as it should've bn done, might not be a difficult thing o have done.

[SWBTATTReg]

9. Hope you get it figured out. Ours went out just a week or so ago, and we're on the biyearly checkup plan on our AC/

furnace, and it didn't kick on, and we thought it was the batteries, etc. being that we'd just had them out there (the AC/furnace people). Turns out that the blower fan went out, and fortunately they had a replacement for it. Came in, replaced it, and viola! AC!

One thing that helped is that we're had them here at the house twice a year for at least 11 years, so we do get rather fast service when we need it. We also have 3 window units just in case to use, although w/ the AC/furnace unit, we don't need, but I won't get rid of them just in case.

Good luck to you.

[SheltieLover]

16. Glad you got it fixed quickly!

I hear you. We have 3 window ACs, an extra mini split installed in a bedroom & a whole house mini split on ice in case the main unit fails.

[Deuxcents]

10. Mine did that before I replaced the whole system so I turned the a/c breaker off at the main box.

Waited about 20 minutes and turned it back on. Don’t over load the system and keep the thermostat at about 78*. That worked for me but evidently, the system needed replaced as it was 14 years old.

[Phoenix61]

11. If it uses batteries when they die the system will shut off.

[KY_EnviroGuy]

12. A few notes.

Marthe, I've worked on a number of these type units as a Mr. Fix-it for friends and my own systems, so here are some observations and hints:

Your main furnace & A/C evaporator cabinet (I assume in your basement) has a master control circuit board that controls all the logic of starting, stopping and emergency shutdown for both heating and A/C. The controller has automatic delays built-in to prevent damage to the compressor for A/C use, and to prevent your furnace from overheating or exploding in the winter.

Typically, when there's a new start of the system or a restart attempt, there will be about a 3-to-5 minute delay before the compressor will restart and cooling can resume. This safety delay also occurs when power is interrupted accidentally or during a storm.

Often, the new digital thermostats may have delays as well, mainly to prevent false starts because people can be clumsy getting the settings adjusted. Therefore, when you change the setpoint, there is usually a delay before anything changes in the system.

Your thermostat talks to the basement cabinet controller board and that controller commands the outdoor evaporator/compressor unit to start and stop. It also controls the house main circulating fan and the gas burner (or electrical heating elements) in the winter.

Your controller board may also take inputs from a number of safety switches, including low-airflow (due to plugged air filters) along with safety switches for furnace operation.

Typical breaker and disconnect arrangements:
1. Your basement main cabinet (includes the house circulating fan) will be on one 120V breaker in your panel. There's typically also a local lighting-type toggle switch on the side of that cabinet that disconnects that same 120V circuit. For safety reasons, it allows you to conveniently shut your system down when you change the air filters.
2. The compressor (outdoor unit with condenser exhaust fan) will be fed by a two-gang 220V breaker in your panel and usually also has a local pull-out disconnect mounted on the exterior wall next to that unit. On some older systems, that disconnect also contained cartridge fuses.

And yes, your system will not operate with dead batteries in the newfangled thermostat. Good idea to keep a spare around.

Good luck and hope this helps!

[Marthe48]

14. Thanks, everyone!

I think the new batteries fixed it for now.

I'll bookmark or journal this post for future reference.

Thank you for taking time to write informative posts. The support is so cheering!