What should you do first?
Verify Cool mode, lower the setpoint a few degrees, check the filter, and confirm vents are open. If the outdoor unit is not running, the coil is frozen, water is leaking, or the breaker trips again, turn the system off and arrange diagnosis.
Safe observations
- Confirm thermostat mode, setpoint, and fan setting
- Inspect the filter and visible return airflow
- Look at the outdoor unit without reaching inside or removing panels
- Check for visible ice or water and note where it appears
Warning signs and stop conditions
- Breaker repeatedly trips
- Burning smell, buzzing, or sparking
- Ice covering refrigerant lines or the indoor coil area
- Water near electrical components
- Outdoor unit starts and stops rapidly
Possible causes
Restricted airflow
A loaded filter, blocked return, dirty indoor coil, blower fault, or duct restriction can reduce cooling and sometimes contribute to icing.
Outdoor unit problem
A failed capacitor, contactor, fan motor, compressor, disconnect, or control signal can leave the indoor fan running while the condenser stays off.
Refrigerant-side fault
Leaks, metering problems, or compressor issues require instruments and trained service. Refrigerant is not a homeowner repair.
Professional diagnostic context
- Thermostat call and control signals
- Filter, temperature split, blower, coil, and airflow
- Outdoor electrical components, fan, and compressor
- Drainage and condensate safety switches
- Refrigerant performance when justified by testing
What an estimate should explain
- 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
Repair and replacement decisions
A control, drain, or common electrical component may support repair, while a compressor or leaking coil on older equipment may justify comparing replacement. Age alone is not a diagnosis; ask for measured findings and written options.
Questions and answers
Why is my AC running but not cooling?
Common categories include thermostat settings, restricted airflow, a frozen coil, outdoor-unit failure, or a refrigerant or compressor problem. The visible symptom alone cannot confirm the failed part.
Should I run an AC with ice on it?
No. Turn cooling off and avoid chipping the ice. Continuing to run a frozen system can worsen the problem; professional diagnosis may be needed after it thaws.
Can a dirty filter stop an AC from cooling?
A heavily restricted filter can reduce airflow and cooling and may contribute to icing. Use only the correct filter size and installation direction.
Do I need refrigerant every year?
A sealed system should not need routine refrigerant top-offs. Low charge can indicate a leak or another fault that needs diagnosis.