What should you do first?
Start with the thermostat, filter, and visible airflow. If the air stays warm, the outdoor unit is silent, ice forms, water leaks, or the breaker trips, stop repeatedly restarting the system and arrange professional diagnosis.
Safe first checks
Before requesting repair
- Set the thermostat to Cool and lower the setpoint a few degrees
- Check the air filter and open supply and return vents
- Listen for the indoor blower and observe the outdoor unit from a safe distance
- Look for ice on visible refrigerant lines or water around the indoor equipment
Stop and call
Warning signs that need more caution
- Ice on the coil or refrigerant line
- Breaker trips more than once
- Burning odor, harsh buzzing, or grinding
- Water near wiring or controls
- Outdoor unit runs with severe noise or fan failure
Possible causes
What may be behind the symptom
Restricted airflow
A dirty filter, blocked return, blower issue, dirty coil, or duct restriction can reduce heat transfer.
Outdoor condenser failure
The fan, capacitor, contactor, disconnect, control, or compressor may not be operating correctly.
Frozen coil or refrigerant fault
Low airflow and refrigerant-side problems can contribute to ice. Let it thaw with cooling off and have the cause diagnosed.
Professional diagnosis
What a technician may inspect
- Thermostat and controls
- Filter, blower, coil, duct, and temperature split
- Outdoor fan, capacitor, contactor, and compressor
- Drainage and condensate safeties
- Refrigerant pressures and temperatures when warranted
Cost context
What can affect repair price?
- The system type, capacity, age, and accessibility
- The failed component and whether compatible parts are available
- Diagnostic or service-call fees in the local market
- After-hours timing and current provider availability
- Refrigerant type, electrical work, and any additional testing required
Common questions
Frequently asked questions
How long should I wait for the AC to cool?
You should usually feel a clear temperature difference at the vents within several minutes. Whole-home recovery can take longer, especially after a hot day or long shutdown.
Can I thaw a frozen AC myself?
Turn cooling off and leave the fan setting as recommended by the equipment instructions. Do not chip ice or use heat. Diagnosis is still needed if ice returns.
Why is the indoor fan running but the outdoor unit is off?
A disconnect, breaker, control signal, capacitor, contactor, motor, or compressor problem is possible. Avoid opening panels or touching electrical parts.
What should I tell the technician?
Share when cooling stopped, whether the indoor and outdoor units run, any ice or water, unusual sounds or odors, and whether a breaker tripped.