Before you call
These quick checks can catch a simple setting, airflow, power, or drain-safety issue. Stop at anything that requires opening equipment, touching wiring, handling refrigerant, or bypassing a safety.
Quick homeowner checklist
Work through these in order. If the system starts again, keep an eye on it. If the same problem returns, there is still a cause that should be checked.
Set the system to COOL, set the fan to AUTO, and lower the setpoint a few degrees below the room temperature. Replace thermostat batteries if the screen is blank. After making a change, allow up to five minutes for the built-in delay.
With the thermostat calling for COOL, wait up to five minutes. Inside: listen for the blower and feel whether air is coming from a supply vent. Outside: from a safe distance, listen and look for the outdoor fan. Write down one of these: both running, inside only, outside only, neither, or starts and stops.
Find the filter at a return grille or near the indoor unit. If it is packed with dust, replace it with the same size and install the airflow arrow toward the air handler. Do not force in a filter that does not fit.
Check the labeled A/C or heat-pump breaker and the air-handler or furnace breaker. If one is tripped and the area is dry, reset it once only if you are comfortable doing so: move it fully OFF, then ON. If it trips again, stop and call. Also confirm the light-switch-style service switch near the indoor unit was not turned off.
Make sure supply registers are open and not covered by rugs or furniture. Keep return grilles clear. A blocked return or heavily restricted airflow can reduce cooling and contribute to coil icing.
From a safe distance, check whether the fan is running and whether leaves, grass, or storage are blocking airflow. Clear loose debris around the cabinet, but never reach through the grille, open a panel, or touch wiring.
Check around the indoor equipment and drain pan for standing water. A float switch is a small safety device on the PVC drain or in the drain pan that shuts the A/C off when condensate backs up. If you see water or a raised float, turn cooling off, take a photo, and call—never bypass, tape down, or force the switch.
Look for ice on the larger insulated copper line or around the indoor unit. If you see ice, turn COOL off and let the system thaw. Replace a visibly dirty filter if needed, but do not chip or scrape the ice. Call if it freezes again or water begins leaking.
What is a float switch?
Air conditioners remove humidity and send that water through a condensate drain. If the drain backs up, the float rises and opens a low-voltage safety circuit, often stopping the indoor or entire A/C system before the pan overflows. A shutdown plus water at the indoor unit is a strong clue. Leave the switch in place and let the drain problem be corrected.
Match the symptom
This is not a repair diagnosis. It helps you gather useful information and avoid overlooking a simple homeowner-level issue.
Start with thermostat power and settings, both HVAC breakers, the indoor service switch, and visible water around the float switch.
Confirm the thermostat is calling for cooling and check the labeled outdoor-unit breaker. Do not open the disconnect or equipment panels; report this pattern when you call.
Check the filter, indoor breaker, and indoor service switch. Turn cooling off if the outdoor unit is running without indoor airflow and call for service.
Confirm COOL and AUTO settings, inspect the filter, check for ice, and note whether airflow is strong, weak, warm, or room temperature.
Turn cooling off if water is near electrical parts. The drain or float switch may need service; do not bypass the safety.
Open registers, clear return grilles, note which rooms are affected, and tell us whether the problem is constant or changes during the day.
Stop the system if it is safe to do so and call. Do not keep resetting a breaker or running equipment that smells electrical.
Help us arrive ready
A few minutes of access prep can prevent delays and gives the technician more time to focus on the system.
