What to Do About a Frozen Evaporator Coil

If you’re trying to figure out what to do about a frozen evaporator coil, you’re likely dealing with an uncomfortable home. Maybe you have warm air blowing from your vents, or even a completely non-functioning air conditioner. A frozen evaporator coil might be to blame. This is one of the most common cooling issues homeowners have to deal with, and knowing what to do about a frozen evaporator coil can help prevent costly repairs. By following the right steps, you can get back to comfort and protect your air conditioning system from permanent damage.

Why Does an Evaporator Coil Freeze?

The evaporator coil’s job is to absorb heat from your home. When that gets interrupted, you could be dealing with a frozen evaporator coil. Lower temperatures inside your air conditioning unit can cause the moisture in the air to freeze on the metal surfaces. So basically, you’ll get a frozen evaporator coil when the evaporator coils drop below freezing. Anything that restricts airflow or affects refrigerant levels can cause the coil to ice over. 

What Causes Ice Buildup on Your Air Conditioning Unit?

There are a variety of issues that can cause ice buildup on air conditioner coils. One of the most common culprits is a clogged air filter. You’ll run into airflow restriction from dirty air filters, which is why it’s important to swap them out on a regular basis. A dirty evaporator coil blocks proper airflow.

Another problem might be low refrigerant levels. This would happen because of a refrigerant leak. You could also be dealing with a malfunctioning air handler fan. Less likely, but still possible, would be having a thermostat that keeps the system running for too long.

In extreme cases, you could have locked or collapsed ductwork. Similarly, there might be severely clogged refrigerant lines. Any of these issues can cause your evaporator coil to drop in temperature, even to freezing. When that happens and the coil is frozen over, the system will no longer be able to complete the normal cooling process.

How Do You Know If Your Evaporator Coil Is Frozen?

When your evaporator coil freezes, the symptoms are usually obvious. Your system will malfunction. Still, many homeowners don’t realize what’s happening until the AC unit stops working entirely. That’s why it’s important to stay on top of issues early, before they get out of hand.

What Are the Warning Signs of Frozen AC Coils?

Warm air or hot air coming from vents is a sure sign that something is wrong with your system. It might be because of a frozen evaporator coil. On the other hand, you might just have little to no air flow through the system. Inside, you might notice a sudden increase in indoor humidity because the AC system is running constantly but not cooling. The best way to check is to go straight to your AC unit. If you see visible frozen coils or ice on the evap coil, then you know the problem!

You might also check to see whether there is ice on the refrigerant lines or outdoor unit. Another sign is if there’s water dripping from the drain pan. If you notice any of these issues, you’re likely dealing with a frozen evap coil and need to take action immediately.

What Should You Do Immediately When You Find a Frozen Coil?

When your evaporator coil freezes, you should first turn off your air conditioning. Continuing to run the air conditioner when the coil is frozen can cause compressor failure. This is a costly repair that could mean replacing the entire air conditioning system.

Is It Safe to Keep Running Your Air Conditioner With Frozen Coils?

No. Running the system with frozen AC coils forces the compressor to work without proper refrigerant flow. This can result in overheating and permanent compressor damage. You’ll obviously have reduced cooling performance too, which means you’re just wasting energy while potentially damaging your system along the way.

Instead, turn off the cooling mode and switch the thermostat to fan only. This helps warm air circulate over the ice so you can get a natural thawing process.

How Do You Fix an Evaporator Coil That Freezes?

Once the system is off, you need to wait for the ice to melt. This can take several hours, depending on how badly the coils freeze. Once you turn off the cooling, set the fan to ON. From there, you can check and change clogged filters, since this is the easiest thing to fix and a common issue. You also want to be sure that nothing is blocking the outdoor unit. If you’re dealing with a heat pump system, you might be in luck. These sometimes have a defrost mode, which automatically warms the coil in certain conditions.

How Long Does It Take an Evaporator Coil to Thaw?

A frozen evaporator coil can take anywhere from 2 to 24 hours to thaw. It all depends on how thick the ice buildup is. Whether the fan is running makes a difference, and typically it’s a good idea to have the air circulating. Your indoor temperature also matters. Hotter days mean quicker thaw times. Also, be sure that your system has good airflow with a clean filter.

Once thawed, call an HVAC technician if the coil freezes again—persistent freezing typically means you’re looking at low refrigerant levels or more complicated airflow issues that need professional repair.

How Much Does It Cost to Fix a Frozen Evaporator Coil?

The cost to fix a frozen evaporator coil depends on what caused the frozen evaporator in the first place. A clogged filter replacement is relatively easy, just $10–$40. Fixing refrigerant leaks and recharge can run you from $300–$1,200. The worst-case scenario is when you have compressor damage from continuing to run your system. This can mean repair costs of $1,200–$3,000. Fortunately, shopping at Surplus City can help you get affordable repair parts, so you only have to focus on the labor.

Do the simple things you can to thaw your evaporator coil and be sure to address the issue early. By knowing what to do about a frozen evaporator coil, you can prevent future damage and higher repair costs.