Safe Homeowner Checklist
- 1Confirm the thermostat is set to Cool, not Heat, Off, or Fan only.
- 2Lower the set temperature several degrees below the current room temperature.
- 3Replace batteries if the thermostat uses them and the display is weak or blank.
- 4Wait five to ten minutes if the thermostat shows Wait, Delay, or compressor protection.
- 5Look for water near the indoor unit that may point to a float switch shutdown.
- 6If safe and clearly labeled, reset the AC breaker once. If it trips again, stop.
Call a Technician If...
- Cool stays on the thermostat but no indoor or outdoor equipment starts.
- The indoor fan runs but the outdoor unit stays off.
- The system turns on briefly and shuts off again.
- Water near the indoor unit suggests a drain safety switch.
- The breaker trips again after one safe reset.
- You suspect thermostat wiring, control board, transformer, or equipment failure.
Why Cool does not always mean cooling
Many thermostats show Cool when they are asking for cooling or preparing to ask for cooling. A delay can protect the compressor after a recent cycle or power interruption.
If the delay clears and the equipment still does not run, the problem is beyond a normal thermostat wait.
Float switch and drain clues
A clogged condensate drain can trigger a float switch that stops cooling to protect the home from water damage.
Do not bypass that safety switch. If water is present, the drain needs service.
When This Becomes Repair vs Replacement
This is commonly a repair when the cause is thermostat setup, batteries, a clogged drain safety switch, control wiring, or a replaceable control part.
Replacement becomes a discussion if the no-cooling call reveals major equipment failure, repeated electrical failures, or an older system that has been unreliable.
Ask the technician to separate thermostat/control repair from larger equipment condition so you can make a clear decision.