Air Conditioner Coils Icing Over

If your air conditioner coils are icing over, the problem could be caused by restricted airflow, a dirty air filter, low refrigerant, or a faulty blower motor. Before replacing any parts, inspect the most common causes listed below.

Safety Notice: Always turn off power to the air conditioner before servicing it. If the evaporator coil is covered in ice, allow it to thaw completely before inspecting or testing any components.

Possible Causes

  • Dirty or clogged air filter
  • Low refrigerant level
  • Failed blower motor
  • Blocked or closed air vents
  • Dirty evaporator coil
  • Faulty blower motor capacitor
  • Defective thermostat
  • Restricted ductwork

1. Dirty or Clogged Air Filter

Most Common Solution

A dirty air filter restricts airflow across the evaporator coil. Without enough warm air moving over the coil, condensation can freeze and eventually cover the coil with ice.

What to do:

  • Turn off the air conditioner.
  • Remove and inspect the air filter.
  • Replace the filter if it is dirty or clogged.
  • Allow the coil to thaw completely before restarting the system.

2. Low Refrigerant Level

Low refrigerant reduces the pressure inside the evaporator coil, causing the coil temperature to drop below freezing and allowing ice to form.

What to do:

  • Allow the evaporator coil to thaw completely.
  • Inspect the system for signs of refrigerant leaks.
  • Have the refrigerant level checked and the leak repaired before recharging the system.

3. Blower Motor

The blower motor moves warm indoor air across the evaporator coil. If the motor fails or operates at a reduced speed, the coil can freeze.

What to do:

  • Listen for the blower motor while the system is running.
  • Verify air is flowing from the supply vents.
  • Replace the blower motor if it is defective.

4. Blocked or Closed Air Vents

Closed supply vents or blocked return vents reduce airflow through the HVAC system, increasing the likelihood of the evaporator coil freezing.

What to do:

  • Open all supply and return vents.
  • Remove furniture or objects blocking airflow.
  • Verify unrestricted airflow throughout the home.

5. Dirty Evaporator Coil

Dust and debris on the evaporator coil reduce heat transfer and restrict airflow, allowing ice to accumulate.

What to do:

  • Turn off power to the unit.
  • Inspect the evaporator coil for dirt or debris.
  • Clean the coil using an approved evaporator coil cleaner.

6. Blower Motor Capacitor

A weak or failed blower motor capacitor can prevent the blower from operating at full speed, reducing airflow across the evaporator coil.

What to do:

  • Disconnect power.
  • Inspect the capacitor for bulging or leaking.
  • Test the capacitor with the proper equipment.
  • Replace it if it is defective.

7. Thermostat

A malfunctioning thermostat may cause the air conditioner to run continuously, increasing the chance of ice forming on the evaporator coil.

What to do:

  • Verify the thermostat is set correctly.
  • Test the thermostat for proper operation.
  • Replace it if it is defective.

8. Restricted Ductwork

Collapsed, blocked, or disconnected ductwork can reduce airflow enough to cause the evaporator coil to freeze.

What to do:

  • Inspect accessible ductwork for obstructions or damage.
  • Repair disconnected or crushed ducts.
  • Restore proper airflow before operating the system.

Need Help Finding the Correct Part?

If you need help identifying the correct replacement part, send us your complete air conditioner model number and a clear photo of the appliance identification label before placing your order. Our team will verify compatibility and help ensure you receive the correct replacement part the first time.