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What Does Ice on AC Coils Mean?


Ice on AC coils in Fresno, CA typically indicates an issue with your air conditioner that needs attention. You might think at first that ice isn’t a big deal—it just means that the AC is working hard. But ice is not part of the cooling cycle of an air conditioner. We’ll explain below why ice may appear on your air conditioning system’s evaporator coil and what to do about it and prevent it.

Main Causes of Ice on AC Coils

  • Restricted Airflow: One common cause of ice formation is restricted airflow over the evaporator coil. This can occur due to a dirty air filter, blocked vents, closed or blocked registers, or obstructed ductwork. Restricted airflow prevents warm air from reaching the evaporator coil, causing it to drop below freezing and accumulate ice.
  • Low Refrigerant Levels: Insufficient refrigerant levels can lead to low pressure within the system, causing the evaporator coil to become colder than it should. When the coil temperature drops too low, moisture in the air condenses and freezes on the coil surface.
  • Dirty Coils: Dirt, dust, and debris can accumulate on the evaporator coil over time, insulating it and hindering heat exchange. This insulation effect can cause the coil temperature to drop excessively, leading to ice formation.
  • Malfunctioning Components: Faulty components such as the blower motor, fan relay, or thermostat can disrupt the proper operation of the AC system, leading to ice formation.
  • Incorrect Installation: Improper installation, such as undersized ductwork or an incorrectly sized air conditioning unit can lead to inadequate airflow and contribute to ice formation on the coils.

Prevention & Solutions

Observing your air conditioner coil or refrigerant lines wrapped in ice is a troubling sight, particularly if it happens on a summer day. Regular professional maintenance can help prevent ice formation and ensure the efficient operation of your air conditioning system.

If you notice ice on your AC coils, it is important to address the issue promptly to prevent further damage to the system by:

  • Turn off the AC to let the ice melt. Then, troubleshoot the potential causes.
  • Check and change the air filter. Replacing your air filter every one to three months will prevent freeze-ups  and will also ensure good air-conditioner performance and indoor air quality.
  • Check that the blower fan is working properly. A faulty blower fan can also make life hard for your air conditioner, either because it is not able to generate enough airflow to keep the coil from freezing over or because it is not functioning at all.
  • Check the condensate drain line. If any part of the line becomes clogged, the water in the tray will fill up and overflow.
  • Check your vents (supply and return) to be sure that they are not blocked by furniture or another object.

In most cases, you’ll need to have professionals like ours handle the situation: often the core cause won’t be obvious to you, and simply removing the ice won’t solve it. Reach out to us to help with diagnosing the issue and properly repairing it.

Call Purl’s Sheet Metal & Air Conditioning for the AC repair you need in the Central Valley. “Quality is the Cornerstone of Our Success” since 1952.

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