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Air Conditioning Service – Freezing Coils Can Damage Your Central Air Conditioner

by Ben Wanner of Pro Service Mechanical

frozen AC coil

If your air conditioner coil above your furnace is freezing up you need to call your air conditioning service professionals to have your air conditioner checked. Turn off the air conditioner to prevent damage and let the coil thaw out. Frozen coils can cause catastrophic damage to your AC system’s vital components.

Typical Signs Of A Frozen Coil


  • AC not cooling your home properly
  • less airflow at the vents
  • system running continuously
  • ice buildup on refrigerant lines
  • unusual amount of condensate drainage


We will talk about a few simple things you can check if this is happening but again we recommend having it checked by a refrigeration technician as soon as possible. Call the Pros at Pro Service

Typical Causes of Frozen up Coils

Dirty Coils

dirty evaporator coil

You may not be able to access the evaporator coil above the furnace but if you have an inspection panel between the furnace and the indoor coil you can shut the power off to the system at the breaker and have a look with a light and mirror. It will be obvious that it is very dirty and it will likely have ice build up on it. We generally recommend you leave cleaning of the coil to your service technician.

Dirty Filters

dirty air filter

This is of course a simple thing to check and could certainly be the cause of your AC coil icing up. The coil is relying on your house air to bring down the temperature of the refrigerant inside the system. When there is no airflow from dirty filters or coils the refrigerant does not get heated up and freezes your coil. The problem could be this simple.

Low Refrigerant Levels

If we look at the image below we can see how the refrigerant coming to the coil expands to a low pressure liquid. If there is not enough refrigerant in the system then less refrigerant will expand more, reducing the pressure and reducing the temperature too much and causing the evaporator coil to freeze up. This will have to be checked by your technician to ensure the proper level of refrigerant is present.

Air Conditioner System

Mechanical Failure or Controls Problems

These type of problems will have to be addressed by your technician and we will not get in to depth on these specific issues.

Possible Damaging Effects Of Leaving Your System Running With A Frozen Coil.

  • If the evaporator coil freezes then the refrigerant may not heat up enough to turn back into a gas. This means the compressor may see liquid and it is only meant to handle gas. This will damage the compressor very quickly.
  • Premature wear of furnace fan motors are possible due to the restricted airflow that make the fan work much harder than it was designed to.
  • Possible damage to the furnace heat exchanger from moisture and rust. This could cause a safety issue over time.


If you have any other questions feel free to give us a call at (306) 230-2442

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If you are looking for service, repair, installation, drain cleaning or bathroom renovations in the Saskatoon area, then Pro Service has you covered with competitive pricing and that old style service. Some conditions apply. Give us a call today.


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If you have any other questions or concerns about Cooling, Heating or Plumbing call the pros from Pro Service at 306-230-2442. We have 24/7 365 emergency service and we are always here to help.

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