Frozen AC Unit Warning Signs Every Homeowner Should Know

One of the most common air conditioner problems homeowners face is the buildup of frost and ice on the condenser coils. This isn’t typically caused by freezing outdoor temperatures. On the contrary, air conditioners freeze over in hot and humid weather because the moisture in the air freezes on contact with the cold appliance.

You can encounter a frozen AC unit inside or outdoors, and the problem can become more than a temporary inconvenience if neglected. Continuing to run an air conditioner that has frozen over can overwork the machine, leading to equipment failure and the need for a potentially costly air conditioner replacement.

Fortunately, a frozen air conditioner is often easy to diagnose, and remedying the problem is not too difficult. In this article, we’ll walk through some of the signs your AC is frozen and what might be causing it. We’ll also review how to defrost your air conditioner and prevent future freeze-ups.

Common Signs of a Frozen AC Unit

There are a few signs that your air conditioner is frozen over, some of which are obvious and others less so.

• Accumulating ice or frost. Of course, icy buildup on your air conditioner is a clear sign that the appliance is freezing up, but it might take you a while to notice if your unit is situated outdoors, behind or on the side of your home. If you have outdoor appliances, perform periodic walkthroughs to inspect for a frozen condenser or AC unit frozen pipe outside.
• Inadequate cooling. If your air conditioner is not cooling, the unit may be frozen. The accumulated ice actually inhibits the cooling action of the appliance, and while the fan may still operate, it ends up circulating warm air instead of cool air. If your air conditioner is failing to bring down the temperature of your home, check the vents and registers. If you feel warm air, your air conditioner is probably icing up.
• Strange noises. Ice inside an air conditioner or equipment malfunctions that facilitate the buildup of ice can cause all manner of unusual noises: buzzing, rattling, hissing, and clicking. If you are hearing anything beyond the healthy hum of your air conditioner, there could be an icy problem on your hands.
• Excess moisture or condensation. A little condensation on your air conditioning unit can be normal, but an excess of moisture and apparent AC water leaks are worrying signs. They could mean that the coils inside or behind the unit are freezing over.
  

 

Causes of a Frozen AC Unit

Now you know how to spot a frozen air conditioner. But what causes the problem in the first place? The three main contributors are inadequate airflow, insufficient refrigerant, or poor condensate drainage, though each of these issues can themselves have different causes. Here are some more specific possibilities to troubleshoot:

• Clogged air filter. If an air conditioner’s filter is too choked with dust, soot, and grime, the free flow of air diminishes, impeding evaporation and leading to excess condensation within the unit. This moisture freezes, and layers of ice slowly build up.
• Obstructed ducts. A healthy air conditioner system requires constant airflow. If air ducts around your home are obstructed or damaged, enough warm air may not come in contact with the appliance’s coils, and they will freeze up as a result.
• Dust, grime, and debris are common internal duct obstructions. Pest nests are possible too. In some cases, ducts may be crushed or damaged by some external force. Also be mindful that furniture, boxes, tools, and other household belongings are not covering vents around your home.
• Damaged or malfunctioning fans. Another possible cause of inadequate airflow is a damaged or otherwise inoperable blower fan. Again, if there is not any air passing over the condenser coils, they are liable to ice up.
• Leaking refrigerant or coolant. One of the most common causes of a frozen air conditioner is a refrigerant leak. If the refrigerant or coolant level is too low, the temperature of the unit can plunge, leading to the freezing of moisture on the condenser coils.
• Improperly filled refrigerant or coolant. Air conditioners operate with closed refrigerant systems, so you do not need to manually top off refrigerant levels unless there is a leak — which is a serious problem to have remedied by an HVAC professional. That said, the closed system requires a specific quantity of refrigerant, and if your system is improperly serviced and has too little or too much refrigerant, the system will not run efficiently and frozen coils can result.
• Poor drainage. Air conditioners create condensate, which is essentially collected condensation that drains away from the unit and into a pipe to be channeled out of your home. If that condensate does not drain — which can be due to a mislaid drain pan or damaged drain line — the moisture collects and can freeze within the unit.
• Running during cool weather. Your air conditioner is designed to operate in warm weather. If you run the unit when it is too cool outside, you risk freezing the coils. If the outdoor temperature dips below around 60°F, shut off the unit and open a window for a cool breeze instead.
• Extreme weather. More rarely, air conditioner freeze-ups can occur as a result of extreme cold weather. If there is a cold snap after wet and rainy weather or after accumulated snow has started to thaw, unprotected outdoor air conditioner units can freeze. This problem often remedies itself, as the icy buildup is likely to melt away long before you plan on turning the unit on.

How to Prevent a Frozen AC Unit

A little basic preventative maintenance can help you keep your air conditioner from freezing up in the first place. Here are some tips:

1. Replace your air conditioner’s air filter. Cleaning or replacing the filter is one of the simplest — but no less essential — air conditioner maintenance tasks you can do. Clean or replace the filter every three months or so to keep your unit in good shape.
2. Spot check your vents and drain lines. Poor airflow and condensate drainage are leading causes of air conditioner freeze-ups. Periodically check the vents for obstructions or damage, and inspect drain lines for clogs. Also ensure the drain pan is set correctly within the unit.
3. Keep the condenser coils clean. Condenser coils are prone to collecting dust and grime, which can sometimes make the coils more likely to freeze. Keep them clean by wiping away accumulated dust with a rag or towel.
4. Monitor your appliance for leaks. It is a good idea to check your air conditioner for water or refrigerant leaks every couple of weeks. A quick inspection is all that is required. Look for pools or puddles of fluid around the unit and drips down the sides. If the leak is intermittent, you might see signs of dry residue on or around the unit.

What to Do If Your AC Unit Freezes

Sometimes a frozen air conditioner can get the better of you even if you stay on top of your maintenance schedule. If your unit does ice up and the underlying cause is something minor — like a dirty filter — resolving the issue is simple enough.

Defrosting air conditioner condenser coils begins with turning off the cooling action. You could simply turn off the entire unit and wait for the ambient air temperature to melt the accumulated ice and frost. If you want to accelerate the melt, you can keep the unit’s fan running to keep a steady flow of warmer air in contact with the coils. How long to defrost air conditioner coils is dependent on the ambient temperature, amount of accumulated ice, exposure to sunlight, and so on.

Resist the urge to use shortcuts to defrost the coils. Do not try to chip away the ice with a pick or screwdriver, as you risk damaging the coils irreparably. Using a hair dryer may seem like a clever solution, but the high heat can damage the coils as well.

Once you have defrosted your air conditioner, inspect the unit to determine the cause of the freeze-up. Cleaning the filter, resetting the drain pan, or clearing the drain lines are DIY projects, but you should contact a professional if you can’t determine the cause or suspect the problem to be related to a refrigerant leak. Of course, if you have home warranty coverage, you can call on your plan for quick and effective service. Learn more about Liberty Home Guard’s air conditioner coverage options by calling (833)-545-5590.