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What Causes An Air Conditioner To Freeze Up?

By September 20, 2021No Comments
Frozen AC Lines

Your air conditioner has a very big job of keeping your home cool. Sometimes though, your air conditioner can get too cold and freeze up. So what causes your air conditioner to freeze up? Well, it could be many reasons.

Let’s take a look at the top reasons why your air conditioner freezes up and what you can do about it.

How An Air Conditioner Works

Before we dive into each reason, we must first understand how your AC cools the home.

Your AC is filled with a compressible gas, called freon inside small copper tubes. When freon expands, it gets cold. Therefore, when you have the AC running, your AC uses a giant fan to blow your air through your ducts and over the cold copper coils filled with freon.

When the warm air hits the cold copper tubes filled with freon, the coils begin condensing just as a cold water bottle condenses when left outside in the sun.

The condensation leaves your home through the condensation line and warm air that passes through the coils turns cold and blows through your home.

Ultimately, if your AC freezes up air can no longer pass properly through the coils and your home may stay warmer.

Heat-Pump-Diagram-in-Cooling-Mode
How An AC Works

How Your AC Freezes Up

Your AC can freeze up due to many reasons. The root cause is usually because the freon coils get too cold and the condensation freezes over.

Let’s take a look at the possible causes and what to do about it.

Lack of Air Flow

The most common reason for your AC freezing up is a lack of airflow. If the warm air inside your home cannot pass through the coils inside your AC, the condensation can get too cold and freeze over.

A lack of airflow can be caused by your AC fan not blowing properly or not turning on. You may have to replace the fan, or it could be a simple electrical issue.

Additionally, a lack of airflow could be caused by a dirty HVAC filter. Be sure to replace your AC filter so air can pass through.

Refrigerant Leaks

If the refrigerant or freon were to leak, the pressure inside the copper tubes may get too low and get too cold. This could cause your AC to freeze over.

The best way to fix this issue is to add more refrigerant to your AC and see if your AC drops in pressure in a week or sooner. If your AC lines drop in pressure again, then there is a leak somewhere in the copper tubing that should be repaired.

Low Temperature

AC’s are designed to work in a certain range of temperatures. If the temperature inside your home is below 60 degrees, the air may not be warm enough to keep the condensation from freezing over your coils.

To fix this issue, do not run your AC during cold days or nights. A programmable thermostat should help with this problem.

Air_Handler_BlowerFan_25-2
Air handler coils (bottom) and fan (top)

What To Do With A Frozen AC

If your AC happens to freeze up, be sure to lay many towels underneath your AC to catch the dripping water and ice. Then, turn off your AC and wait for the ice to melt.

Once melted, check to see if any of the above reasons were the cause of your AC freezing over. Ask yourself these things:

  1. Is my AC filter clean and is air able to pass over the coils?
  2. Does my fan turn on when the AC is turned on?
  3. Is it just too cold outside?
  4. When did I service my AC last?

Hopefully answering those questions can help lead you to solve the problem.

Final Thoughts

While these are the most common reasons for your AC to freeze up, it could be for other reasons as well.

We recommend contacting your local HVAC company for servicing if none of the above solutions help or you are unsure of what to do.

Many times, these issues are preventable through regular maintenance and servicing of your AC system. We recommend servicing your HVAC system twice a year. View our recommended contractors in Tampa Bay.

Waypoint Property Inspection conducts inspections of AC systems during their home inspections throughout Tampa Bay, FL.

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