How to Troubleshoot Frozen A/C Coils

When your air conditioner suddenly stops blowing cool air, your home can quickly become uncomfortably warm. Before you pick up the phone to call your HVAC technician, you can try troubleshooting one of the most common causes of reduced cooling ability — frozen A/C coils.

Simple Steps for Troubleshooting Frozen Air Conditioner Coils

• Turn on the blower fan – At the thermostat, set the A/C to “fan” so the blower continues to send air across the coil without the cooling components cycling on. The extra airflow can help the coil thaw out faster.
• Warm up the coil – You can also speed up the thawing process by setting a handheld hair dryer on the lowest heat setting and using it to defrost the coil. Make sure you don’t set the hair dryer on the highest setting, as this could damage the coil.
• Clean up any water – Once the coil has completely thawed out, use an old towel to clean up any pooled water that’s accumulated.
• Check the air filter – A badly clogged air filter can severely reduce system airflow and cause the coil to freeze up, so you need to check whether it’s dirty and replace it if necessary before restarting the A/C.
• Use the right filter – Before you install a new air filter, be sure to check that its within the range of acceptable minimum efficiency reporting values (MERV) in your equipment owner’s manual first. Using a filter with too high a MERV rating can also hinder airflow and cause coil icing.
• Test the A/C’s cooling capabilities – Place the thermostat on “cool,” set your desired temperature and wait to see whether cold air arrives at the registers. If there’s no improvement in cool air output, it’s time to call in a professional to check the system’s refrigerant level, which is another possible cause of frozen A/C coils.

At Sobieski Services, Inc., our goal is to help our customers in Delaware, Pennsylvania, Maryland and New Jersey learn more about energy and home comfort issues — especially HVAC and plumbing issues — so that they can save money and live in healthier, more comfortable homes.

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