HVAC Troubleshooting Checklist

Before you schedule a service call, run through these common checks. Simple fixes often resolve the issue and save you money.

AC Not Cooling

Check the thermostat is set to "Cool" and the temperature is lower than the room temp.
Ensure the air filter is clean. A dirty filter restricts airflow.
Check the circuit breaker for the AC unit (indoor and outdoor).
Inspect the outdoor unit for debris (leaves, dirt) blocking airflow.
Verify all registers and vents are open and not blocked by furniture.

Start Advanced Diagnosis →

No Airflow

Check if the thermostat fan setting is "On" or "Auto".
Replace the air filter if it's clogged.
Inspect the blower motor for unusual noises or overheating.
Check for ice on the refrigerant lines (sign of freezing up).
Ensure the furnace/air handler power switch is ON.

Troubleshoot Airflow Issues →

Furnace Not Heating

Set thermostat to "Heat" and raise temp above room temp.
Check that the pilot light handles (if applicable) are ON.
Ensure the gas valve is in the ON position.
Check the furnace filter; a clogged filter can trip the limit switch.
Verify the emergency shut-off switch (often a red plate) is ON.

Diagnose Furnace Problems →

Thermostat Issues

Replace the batteries if the display is blank.
Check for loose wires on the backplate.
Ensure the thermostat is level (for older mercury types).
Verify the date and time settings are correct for schedules.
Reset the thermostat to factory settings if it's acting erratically.

Use AI Diagnostic Tool →

Strange Noises

Tighten any loose screws on cover panels.
Check for debris hitting the fan blades in the outdoor unit.
Listen for "hissing" (refrigerant leak) or "squealing" (belt/motor).
If buzzing, check for electrical contactor issues.
Ruttling? Check for loose ductwork or piping.

Get Professional Help →

Water Leaks

Check the condensate drain line for clogs (algae/slime).
Ensure the drain pan under the unit isn't overflowing.
Pour a cup of vinegar/water mix down the drain line to clear it.
Check if the humidifier water line is loose or leaking.
Inspect for frozen coils melting; this causes sudden water.

Fix Leaking/Freezing →