Updated May 18, 2025
Air conditioner repairs can be costly, so it’s essential to schedule regular maintenance and tune-ups with experienced AC contractors to enjoy the best AC performance.
Also, it’s crucial to learn about the common air conditioning problems so that you can take preventive measures to avoid huge repairs.
Here are 10 common AC problems and their possible solutions:
1. Air Conditioner Is Not Turning On
You must check your thermostat batteries when your AC is not working or turning on. Replace the batteries if they are dead. If the batteries are in working condition, check the thermostat settings to determine whether the cooling mode is on with your desired temperature settings. If your thermostat is on, but your AC is still not turning on, check the circuit breaker. If the circuit breaker is tripped, your AC won’t turn on. Reset the circuit breaker by flipping the switch off and then on.
2. Air Conditioner Not Blowing Cold Air
Your AC will not blow cold air if a dirty air filter blocks the airflow of your unit. A dirty air filter can further freeze up the condenser unit and limit the cooling power of your AC. Changing your air filter every month will help your AC unit blow cold air.
3. Air Conditioner Freezing Up Outside Unit
Your air conditioner can freeze up due to:
- Insufficient airflow
- Low outside temperature
- Low coolant levels
- Blower motor problems
- Stuck contractor
Also, Read – Air Conditioning Maintenance: Tips to Make Your AC Ready for Summer
4. AC Refrigerant Leak
When the coolant in your air conditioner starts leaking, the temperature will vary, and the unit will not perform accurately. Refrigerant leaks can result in:
- Low efficiency
- High power consumption
- Coil freezing
- Damaged compressor
- Uneven cooling
Inspect your air conditioner regularly for any refrigerant leaks.
5. Air Conditioner Making Noises
An air conditioner can make different sounds depending on the type of problems. There are different reasons why your air conditioner is producing a variety of sounds:
- A refrigerant leak can produce a hissing sound.
- If you hear clicking sounds when you turn on and off your AC, it might be a relay problem.
- Thumping, rattling, or banging noises mean there is a problem with a blower or motor assembly.
- The compressor or fan motor produces a screeching noise.
- Faulty electrical components produce a buzzing sound.
6. Frozen Evaporator Coil
The evaporator coil freezes when your air conditioner does not receive sufficient air needed for operation. A frozen evaporator coil can make your AC freeze up and stop working. Blocked vents and ducts, dirty filters, or a faulty fan can cause insufficient airflow in the system. A clean air filter is important to maximize airflow and indoor air quality.
7. Electric Control Failure
When you frequently turn on and off your air conditioner, the fan controls and compressor can wear out. The condenser fan motor, the compressor, and the blower motor make an electrical connection to start the unit. A connection problem can prevent the motor and compressor from turning on. You should check the electrical connections to determine the issue.
8. Air Conditioner Leaking Water Outside
Water leaking outside from your AC on a hot or humid day, especially when the unit is running, is considered normal. It is also normal if the water leakage occurs outside in cool weather at a temperature of 60 degrees or less, as the unit can freeze up and leak water when it melts. Other reasons for your air conditioner to leak water outside, include:
- Dirty air filters
- Improper installation
- Blocked drain pipe
- Low coolant levels
- Broken condensate pan
Also, Read – HVAC Tune-Up Checklist: What Does It Consist of?
9. Drainage Problem
The drain pipeline can also become clogged with dust, algae, and dirt. If water does not drain properly, mold, fungus, and mildew can develop. Also, gasses and bad odor can filter into your home. To prevent this, make sure your drain line is regularly maintained, cleaned, and inspected. Air conditioners which are not mounted level may not drain properly.
10. Sensor Problem
The air conditioner contains a thermostat sensor, located near the evaporator coil. The thermostat measures the air temperature in the evaporating coil and adjusts the cooling based on the condition of the room. If the sensor is forced out of position, the air conditioner can randomly turn on and off or cycle constantly. The sensor should be placed near the evaporator coil without touching each other. Adjust the sensor by bending the wire that holds it in position.
Spotting Uneven Cooling & High Energy Bills
If some rooms feel too warm while others stay cool, or your electric bill spikes unexpectedly, look beyond the thermostat. Uneven cooling often points to duct leaks, blocked registers, or an imbalanced refrigerant charge. Before you assume it’s a thermostat glitch, inspect supply vents in each room for airflow and temperature differences. High energy usage could also signal a failing compressor or dirty condenser coils that force your system to run longer and harder.
Common Ductwork & Airflow Challenges
- Leaky ducts: Even small holes or disconnected joints can waste up to 30% of cooled air. A professional duct sealing or “mastic” application can restore proper airflow.
- Blocked or closed registers: Furniture, carpeting, or drapery can obstruct vents—ensure all return and supply grilles are clear.
- Improper duct sizing: Undersized runs or sharp bends raise static pressure, reducing airflow and increasing noise.
Seasonal Maintenance Checklist
- Spring startup: Clean the outdoor condenser fins and clear a 2-foot radius of debris, vegetation, and leaves.
- Filter swap: Replace or wash filters every 1–3 months—more often if you have pets or high dust levels.
- Condensate line flush: Pour a cup of white vinegar or a specialized HVAC solution down the drain to prevent clogs, mildew, and odors.
- Blower compartment cleaning: Gently vacuum the blower wheel and motor housing to maintain airflow and efficiency.
- Control calibration: Test and recalibrate your thermostat to ensure accurate temperature readings.
When It’s Time for Replacement
Most air conditioners last 12–15 years. If you’ve had frequent repairs, notice significant capacity loss (>20%), or your system uses R-22 refrigerant (now phased out), consider upgrading. Modern high-SEER units can cut cooling costs by up to 40% while providing more consistent comfort. Ask your contractor for a load calculation to right-size your new system and avoid inefficiencies.
Tips for Maximizing AC Efficiency
- Programmable thermostat: Set higher temperatures when you’re away, and schedule pre-cooling 30 minutes before you return.
- Ceiling fans: Use fans on high in summer to create a wind-chill effect—this lets you raise the thermostat by 2–3° without losing comfort.
- Shade your condenser: A shaded outdoor unit runs 5–10% more efficiently; just keep 2 feet of clearance on all sides.
- Window & door seals: Seal gaps with weatherstripping or caulk to keep cool air inside and heat out.
Contact us today to have your air conditioner problems fixed right away by our experienced HVAC contractors.
White Mechanical, Inc.
Founded in 2002, White Mechanical, Inc. in Laguna Hills, CA, is one of the most trusted and licensed (HVAC) service providers, proudly serving Orange County and the surrounding communities. Our management team has more than 28 years of experience in various aspects of HVAC technology. All our HVAC technicians are professionally skilled and certified to deliver outstanding residential HVAC services as well as commercial HVAC services to our clients. We offer professional HVAC services including installation, maintenance, air conditioning repair, and more at very reasonable prices.
