AC Frozen Inside: Why Does It Happen and What to Do About It?

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Last updated: 
June 12, 2018

If you have noticed that your AC unit doesn't quite cool your home the way it used to, or it is working harder to cool your home, which can also increase your energy bill, an AC frozen inside could be the problem. An AC frozen inside can be caused by a number of components, which this short tutorial will help you troubleshoot.

Common Issues with an AC Frozen Inside

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There are various common issues that can occur due to an AC frozen inside, which include:

A Lack of Airflow

An AC frozen inside can cause a lack of airflow, which can make your unit blow out warm air or struggle to cool your home. When this occurs, it can cause premature wear on your unit as well as increase your energy bill as the unit works harder to perform its function.

The A/C Stops Working

If you notice that after running the A/C unit for some time, it freezes up or stops working altogether, ice buildup could be to blame. An AC frozen inside literally causes ice to form on the unit's interior parts, which blocks air to the system and in turn can cause it to stop working.

Ice or Frost Buildup on the Unit's Parts

Low airflow to the A/C unit causes a decrease in temperature inside the system, so when moisture in the air collects on the unit's components, it can create ice buildup on both the inner and outer parts of the A/C.

Never attempt to remove ice from your system by picking or scraping it off with a sharp object because it could damage the parts and lead to costly repairs. Instead, simply turn off the system and wait for it to thaw, or turn on the blower to allow it to thaw, before troubleshooting it.

Tools You'll Need for the Job

Nut Drivers and Sockets

When troubleshooting your system, you will need to access the system's inner parts. Therefore, you will need a set of nut drivers and sockets to remove the panels to inspect the parts.

A Soft Brush

A soft brush, such as a toothbrush, can be used to remove debris from a dirty air filter, which can hinder proper airflow to the system and cause it to freeze up. It can also be used to gently remove debris from the evaporator coils, which can also cause the A/C to freeze up.

A/C Frozen Inside Troubleshooting

There are two main causes of an AC frozen inside, which include low refrigerant and restricted airflow to the evaporator coils.

Turn off the A/C

First, turn off the AC, and turn the fan setting on to allow the system to thaw. Place dry towels around the unit to prevent water damage.

Open the Access Panel to the Evaporator

Remove the access panel to the evaporator. Inspect the coils and the cooling fins surrounding the evaporator. If they have debris on them, gently brush it off using a soft brush.

Check the Air Filters

Check the filters in the cold air return inside your home or in the AC's plenum to see if they are dirty, which can restrict airflow to the system. If they are dirty, simply clean them gently with a soft plastic brush or replace them if they are beyond cleaning.

Check for Refrigerant Leaks

To effectively cool your home, the AC needs the right amount of refrigerant. However, over time, wear and tear on your system can lead to refrigerant leaks, which can cause the temperature of the coils to decrease and eventually cause ice buildup.

Therefore, inspect in and around the system for visual signs of refrigerant leaks, sometimes they can also cause a soft hissing sound. If you find any leaks, simply contact a professional HVAC technician to repair the leaks and then recharge your system.

Turn the A/C Back On

Be sure the A/C supply registers in each room are open. Blocked registers restrict airflow, which causes the temperature inside the unit to decrease.

Turn the A/C back on and allow it to run until it reaches the thermostat setting. If the air still feels warm, the unit still struggles to cool your home, it continues to shut off, or you still notice ice build up on the unit, contact a professional HVAC technician for repairs.

Other Issues that can be Causing an AC Frozen Inside

  • The Wrong Size Ducts - Sometimes the wrong size or number of ducts can cause restricted airflow, which can also cause your system to freeze up.
  • The Wrong Size Condenser - The condenser size, or BTU's, is determined by several factors regarding your building, including the size of the building, how hot the building is, the amount of insulation is inside the walls, and the type of windows. Therefore, if you have the wrong sized condenser for your needs, it can cause the system to freeze up.
  • A Bad Blower Motor - Consistent use and high heat can cause the blower motor on the A/C to burn out, which can cause your unit to freeze up.

Caution Notes

Working with refrigerant, which can be a gas or a liquid, requires a licensed professional, so when dealing with refrigerant leaks and repairs, be sure to contact a licensed professional for help.

Final Thoughts

To prevent premature wear and tear on your A/C, which can cause it to clonk out before its time, and to help keep your energy bills low, don't put off AC frozen inside repairs. Instead, use this short guide on what to do about AC frozen inside to troubleshoot the issue, and then make the repairs that you can yourself to help save time and money.

If you like saving time and money on troubleshooting your A/C issues, wouldn't it be great to share the excitement with your Facebook or other friends? And be sure to share your experience with these troubleshooting tips with us too!

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