When your air conditioner starts acting up in the middle of a hot summer day, it’s frustrating and uncomfortable. While some AC issues require professional repair, many common problems can be identified (and even fixed) with some basic troubleshooting.
In this guide, we’ll walk you through how to troubleshoot the most common AC problems so you can either fix the issue yourself or know when it’s time to call an HVAC expert.
1. AC Not Turning On
Possible Causes:
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Tripped circuit breaker
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Faulty thermostat
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Disconnected power supply
How to Troubleshoot:
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Check the thermostat. Make sure it’s set to “Cool” and the temperature is lower than the current room temperature. Replace batteries if it’s unresponsive.
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Inspect the circuit breaker. A tripped breaker can cut power to the unit. Reset it and check if the AC turns on.
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Check the power switch. Ensure the indoor unit’s switch is turned on.
If everything seems in order but the unit doesn’t power up, it’s best to call a professional.
2. AC Blowing Warm Air
Possible Causes:
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Dirty air filter
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Low refrigerant
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Frozen evaporator coil
How to Troubleshoot:
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Replace the air filter. A clogged filter restricts airflow and affects cooling.
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Check the outdoor unit. Make sure the condenser is running. If it’s off, the issue could be with the capacitor or compressor.
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Look for ice buildup. Ice on the evaporator coil means airflow is restricted or refrigerant is low. Let it thaw before turning the unit back on.
If the warm air persists, professional service is likely needed.
3. Weak or No Airflow
Possible Causes:
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Blocked or closed vents
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Dirty air filter
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Blower motor issues
How to Troubleshoot:
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Inspect vents. Ensure all supply and return vents are open and unblocked.
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Change the air filter. Old filters reduce airflow drastically.
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Check blower motor. If it’s not running or making noise, internal components may have failed.
Call a technician if the motor or fan is not functioning.
4. AC Making Strange Noises
Possible Causes:
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Banging: loose or broken compressor parts
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Buzzing: electrical problems or debris
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Screeching: worn fan belt or motor bearing
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Clicking: relay or thermostat issue
How to Troubleshoot:
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Turn off the system to prevent further damage
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Inspect the outdoor unit and clear any visible debris
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Try to identify the sound source. This will help explain the issue to a technician
Unusual noises usually mean it’s time for a professional inspection.
5. AC Leaking Water
Possible Causes:
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Clogged condensate drain line
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Frozen evaporator coil
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Damaged drain pan
How to Troubleshoot:
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Unclog the drain line using a wet/dry vacuum
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Let the unit thaw if ice buildup is present
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Inspect the drain pan and replace it if rusted or cracked
Persistent leaks should be handled quickly to avoid water damage.
6. Thermostat Not Working Properly
Possible Causes:
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Dead batteries
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Loose or old wiring
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Faulty sensors
How to Troubleshoot:
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Replace the batteries
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Check for loose connections and tighten gently
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Upgrade the thermostat for better accuracy
If issues continue, thermostat replacement may be necessary.
7. AC Short Cycling (Turning On and Off Frequently)
Possible Causes:
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Oversized unit
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Low refrigerant
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Dirty air filter
How to Troubleshoot:
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Replace the filter to improve airflow
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Move the thermostat away from heat sources
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Call an HVAC expert for refrigerant or sizing issues
Short cycling reduces efficiency and stresses your system.
8. High Indoor Humidity
Possible Causes:
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Faulty dehumidification
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Short cycles
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Undersized system
How to Troubleshoot:
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Set the fan to “Auto” to remove more moisture
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Check the drain line to ensure proper draining
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Consider installing a whole-home dehumidifier
Humidity problems can affect comfort and air quality.
Bonus Tips to Prevent Common AC Problems
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Change air filters every 30–90 days
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Keep the outdoor unit clean and free of debris
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Schedule professional AC maintenance annually
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Use a programmable thermostat to reduce system stress
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Seal and insulate air ducts for better efficiency
Proactive maintenance keeps your system running smoothly.
When to Call a Professional
If you’ve tried the steps above and your AC still isn’t performing as expected, it’s time to contact a licensed HVAC technician. Don’t risk further damage or personal injury.
You should call an expert if:
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Refrigerant is leaking
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The compressor fails
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Electrical components aren’t working
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There are persistent or worsening issues
Need Help with Your AC?
If you’re located in Murrysville, Delmont, Monroeville, or nearby areas, The Heating and Air Conditioning Experts are here to help. We offer fast and reliable AC repair and maintenance to keep your home comfortable.
Call us today at (724) 989-8569 to schedule your service.
Knowing how to troubleshoot common AC problems can save you time and money. While many issues have simple solutions, others require the skill of a licensed technician.
Regular maintenance and early attention to problems will help your AC system run efficiently all season long.
