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Why Is My Air Conditioner’s Refrigerant Line Covered in Ice?

Closeup of an outside refrigerant line connected to a white stuccoed home.

Are your refrigerant lines covered in ice?

Phoenix is hot all year round but especially scorching in the summer. As you run your air conditioner, you may see ice building up on your outdoor AC pipes (also called the refrigerant lines), which can seem improbable in the heat. Not to mention that ice on your refrigerant lines indicates that your AC has stopped blowing cold air, which is definitely something you don’t want in Arizona.

This blog will look at the 2 most common reasons why there is ice all over your refrigerant lines even when it’s unbearable outside:

Unsure which problem you have? Don’t worry. We’ll explain both situations, their causes, and potential solutions.

Want to Skip the Hassle of Troubleshooting Your Ice-Covered Air Conditioning Unit?

Contact George Brazil HVAC at (602) 842-0009 to have a highly-trained technician repair your AC! Phoenix homeowners trust us to provide honest diagnostics and flat-rate pricing, as evidenced by our thousands of 5-star reviews.

Schedule with us today for fast, same-day service.

Not Enough Airflow Over the Evaporator Coils

Closeup view of frozen evaporator coils.

Evaporator coils freeze if there isn’t enough warm air blowing over them.

The evaporator coil is an air conditioner part that holds refrigerant. This cold chemical agent absorbs heat from the indoor air and then travels through refrigerant lines to dump the warmth outside. During this process, the chilled air recirculates back into your home via air ducts and vents.

In order to complete its job, the evaporator coil must have enough warm airflow coming into the AC system to push out enough cooled air to match your thermostat temperature. Not enough airflow will freeze the evaporator coil since refrigerant can be as cold as 10-20 degrees Fahrenheit without the warmth counteracting it. Ice then forms on the refrigerant lines.

What can restrict airflow over evaporator coils?

  • Obstructed air vents: Obstructed return air vents prevent the AC system from pulling in warm air. Make sure your air vents aren’t closed or blocked by furniture.
  • Dirty air filters: An air filter clogged by dirt and dust will significantly reduce the airflow your AC can intake.
  • Blower fan issues: The blower fan inside your AC unit’s air handler pushes cooled air throughout your home. A malfunctioning blower fan limits or slows the warm air entering your AC unit and the cooled air from recirculating.
  • Leaky air ducts: Similar to a broken blower fan, leaks in your air ducts reduce the air coming in and out of your AC system, and any cooled air will escape into your crawl spaces instead, which means you’re paying to chill areas that don’t need it.
  • Dirty evaporator coil: A thick layer of dust on your evaporator coil stops warm air from making direct contact with the cold surface, making the refrigerant ineffective at cooling the air.

What to Do

If you suspect that there isn’t enough airflow over your AC’s evaporator coils, follow these steps:

  • Check that your air vents are open and unobstructed: Inspect both the supply air vents that push air into your home and the return air vents that pull air into your AC system. Yes, this includes vents in unused rooms.
  • Replace your air filters if they are dirty: Changing your air filters every month during the summer, every quarter during cooler months, or whenever you see them clogged with dirt is a great way to prevent a variety of AC problems.
  • Turn your thermostat settings to OFF and your blower fan to ON. Typically, we avoid recommending the “ON” setting to homeowners since it means the fan will blow air even if the AC isn’t running a cooling cycle. However, in this case, that’s exactly what we want to help defrost the refrigerant lines. Keep the fan ON and AC system OFF for 3-4 hours.

If you still see ice on your refrigerant lines after completing these 3 steps, it’s time to call in the experts.

Now that you know the purpose refrigerant serves, let’s discuss how a leak can affect the ice buildup.

A Refrigerant Leak

Digital image drawing showing how the refrigerant works in a closed-loop system between the outdoor unit, refrigerant lines, and the indoor unit.

Refrigerant works in a closed-loop system.

When refrigerant levels in your AC system decrease, the pressure inside your evaporator coil also decreases. The temperature in the coil drops in tandem because there isn’t enough chemical fluid to counterbalance the warm air intake. Over time, the chillier temperatures cause ice to form on the coil and lines.

Only one issue can cause the refrigerant levels to change: a refrigerant leak. You see, refrigerant is inside the evaporator coil, which is a closed circuit. It never gets “used up” during your AC’s lifetime. If there is a hole in the evaporator coil or refrigerant lines, the refrigerant will leak out.

You can tell if you have a possible refrigerant leak when you:

  • Hear a hissing or bubbling sound when you stand near the refrigerant lines
  • Feel warm air coming from the vents even if the AC is actively on
  • Receive higher-than-normal utility bills

What to Do:

  1. Turn your thermostat settings from COOL to OFF.
  2. Turn the thermostat fan setting to “ON” and wait 3 to 4 hours for the entire system to thaw out.

Are your refrigerant lines still frozen? Have a professional repair your AC system if you suspect a refrigerant leak. It’s a toxic substance, and HVAC technicians should be the only ones to handle it directly. They should first repair the leak before recharging the refrigerant to the proper levels.

Contact George Brazil for a Reliable Same-Day Air Conditioning Repair!

Since 1955, we’ve provided Phoenix homeowners with superior 5-star customer service and high-quality AC repairs. We also provide our fellow Arizonans with some of the best labor warranties in the area.

Call us today at (602) 842-0009 for a same-day turnaround and our red-carpet rollout. Our technicians will carefully inspect your AC system, explain the problem, and provide an upfront estimate before any work begins.