My Evaporator Coil Is Frozen: WHy?

It’s a sweltering day outside, the humidity is high, and worst of all your A/C isn’t keeping up. But when you go outside to see if your system is running, you see ice on your lines and coil. How is that possible?

If this happens to you, then your evaporator coil is most likely frozen, which means that all that freezing cold refrigerant is flowing into the outdoor lines (causing them to also be covered in ice).

First thing’s first: Turn off your A/C and turn your fan setting to “ON”.

This will force warmer air over the coil and help it thaw faster. Even more importantly, interrupting the cooling cycle will help prevent any further damage to the compressor, which basically serves as the system’s “heart” by pumping refrigerant throughout the system..

While you may be tempted to try and break that ice off by hand, it is very important that you resist that urge! The copper lines and metal fins on your system are easily damaged, which means forcefully removing the ice that’s formed on them could do more harm than good.

It’s also important to note that defrosting your coil and lines is not a permanent solution to your problem. Unless you have a professional determine the root problem, your A/C will continue to freeze up every time you turn it on..

So, to save you time (and maybe a bit of money), here is some information that may help you out:

  • Why evaporator coils freeze
  • Quick tips for fixing a frozen A/C
  • What might really be going on (if those earlier tips didn’t work)

Why do evaporator coils freeze?

Your evaporator coil is made up of a group of copper tubes with refrigerant inside them. As air flows over the coil, the refrigerant absorbs the heat and carries it away towards the outdoor condenser coil. However, when the tubes get too cold, moisture in the surrounding air can condense and freeze onto the coil, which can make it really hard for your system to do its job.

Generally speaking there are a few things that can make the system freeze including:

  • Insufficient airflow
  • Low refrigerant levels
  • Mechanical issues

So now that we know what might be happening, here are a few things to try before calling a professional.

What to do before picking up the phone:

  1. Check your air filter – A dirty filter makes your system work harder by reducing the air flow over the coil. Less air flow makes it easier for moisture in the air to collect on the coil and freeze. A/C Masters recommends checking your filter at least once a month and replacing it whenever it appears dirty or clogged.
  2. Look for closed supply vents – Closing supply vents reduces air flow over the coil by forcing your system to circulate air in a way other than intended. Even when rooms are unoccupied or unused, it’s important to keep those vents open!
  3. Check your return – A return is the vent where air is sucked into your system. Typically, your air filter(s) is also located in the same place. Some houses have multiple returns, some only one, but either way it is important to make sure these airways remain open so that air can circulate unobstructed through your system. 

Unit still freezing up? It could be one of these issues instead:

  1. Refrigerant leak –HVAC lines are sealed systems, meaning that if you have low refrigerant, then you have a leak. That means that you will need a properly trained technician to evacuate the remaining refrigerant in order to find and – if possible – fix the leak.
  2. Malfunctioning indoor blower – An improperly functioning indoor blower will not deliver enough air to the coil, thereby causing it to freeze up.
  3. Dirty evaporator coil – Evaporator coils can often be clogged by dirt, hair, and other debris which (again) block airflow, thus causing the coil to freeze.
  4. Faulty contactor – When a living space reaches the correct temperature, the system should shut down until more cooling is called for by the controller (thermostat). A faulty contactor can prevent this from happening, and thereby cause the coil to freeze as increasingly cold air is passed over it, even when the thermostat is turned off.

If the quick fixes don’t work, and the A/C is still freezing up, it’s important to call a professional for help.

Air conditioners that continuously freeze will eventually lead to more severe problems, which means expensive repairs for you and no cold air when you need it most.

So act now, and let our certified technicians get your home back to where it needs to be: cool and comfortable.

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