Frozen Coil

Frozen evaporator coils is a very common problem amongst air conditioners. These coils can freeze due to a variety of reasons. If not addressed early enough, the frozen coil could cause serious damage to your system, requiring some costly repairs. However, a frozen coil may not always be visible ice around the coil. There are other symptoms of a frozen coil. Here are some telltale signs of a frozen coil:

  • 1. AC is not properly cooling
  • 2. Condensation/ice on the refrigerant line
  • 3. Condensate drain line plugged
  • 4. Drain pan overflowing


Ultimately, anything that interrupts airflow can cause it to freeze. However, there are a number of things that can obstruct airflow. This can vary from a leak, a closed register, or even a dirty filter. Here are the top 3 explanations of why your evaporator coil is freezing.

1. Refrigerant Levels/Leaks

Refrigerant leaks are very common with regular use on the air conditioner. A low refrigerant level or a leak could be the reason your coil is freezing. Low refrigerant levels are a rather easy fix.  However, leaks pose a greater problem. If the leaks go untreated for too long, it can put a strain on the air conditioner. HVAC technicians can detect and fix leaks and add more refrigerant to fix this issue.

2. Drainage Issues

The condensation, especially in high humidity areas, needs proper drainage. The condensation needs to be draining properly to prevent this. A clogged drain pipe can cause too much condensation to develop on the coils, and thus, causing them to freeze.

3. Insufficient Airflow

Improper airflow coming in from the blower can cause the evaporator coil to freeze. Bad airflow can be due to a dirty air filter, a clogged drain, low fan speeds, closed registers, or a dirty evaporator coil. Air conditioner coils need to be properly maintained to guarantee proper efficiency and low cooling costs. Check out Trane’s Coil Maintenance page here for more coil tips.

What to Do When You Have a Frozen Evaporator Coil:

In conclusion, frozen evaporator coils need to be addressed early to avoid long term damage. Luckily, there are some easy things a homeowner can check before bringing in a professional. First things first, air conditioners with a frozen coil should not be running, as it can cause serious damage to the compressor. Turn off your air conditioner to thaw the coil. Nothing can be done until the coil is fully thawed, which can take several hours. Secondly, check the air filter to see if that needs a changed, then check to see if there is any closed registers in your home. If none of these were a problem, then call an HVAC technician. The technician will go through a troubleshooting process to detect and solve the problem. Regular maintenance of air conditioners allows technicians to catch these problems before they happen. Check out our blog for more info about why preventative maintenance is so important.