Thermostat Acting Up

Most "broken thermostats" are dead batteries or a tripped float switch on the AC. Easy to rule out before calling for service.

Difficulty: Easy Time: 10 min Cost: $0–$10

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1

Try new batteries

Pull the thermostat off the wall (most pop off straight). Replace batteries even if it appears on.
2

Check the AC drain float switch

Look at your indoor unit for a small white plastic device on the drain line. A tripped float switch (from a clogged drain) cuts cooling. Clear the line with a wet/dry vac at the outdoor drain end.
3

Confirm the program is reasonable

Programmable thermostats sometimes get into a setback mode. Check the schedule.
4

If smart thermostat — check WiFi

Some smart thermostats stop calling for heat/cool when offline. Reconnect to WiFi via the app.