Why is there Ice on Your AC?
For some people it’s counterintuitive that it is bad for a system that is supposed to cool you down to have ice build up. More ice is more better, right? 🤪 Wrong 🤓
Ice build up on either the evaporator coil, the condensing unit coils, or both, is a sure sign that your air conditioning system is not working properly. Continuing to run it in this condition can cause significant and permanent damage.
If your AC has ice build up on it right now, or even its blowing warm air, turn it off. You’re going to have to finish this blog with no AC.
First I am going to bore you with how an AC works
I won’t go into the nitty gritty technical stuff though. Your air conditioner doesn’t cool your air per se. It moves the heat from your indoor air to the exterior…blah blah blah.
Your air conditioner is made up of 6 main components – the condensing unit which is the outside unit has a large fan blowing air upwards; the compressor which is located inside this unit compresses refrigerant in gas form; there are coils which wrap around the condensing unit; the evaporator coil which is inside the air handler cabinet that is indoors; the blower inside the air handler cabinet which blows air through the ducts; and the line set that connects the indoor and outdoor coils together.
Another important component is good airflow, but we will touch on that more in a bit.
A super simple explanation is that the compressor circulates the refrigerant between the outdoor and indoor units.
Outside the fan cools the refrigerant enough to change it from gas to a liquid.
An expansion valve cools the refrigerant further
The cold refrigerant passes through the indoor evaporator coil
The blower blows air across the indoor evaporator coil
The heat from the air is transferred to the evaporator coil
Cool air is distributed to the home through the ducts and vents
The refrigerant travels back to the outdoor compressor and the process repeats
Super simple, right?
What are the Symptoms of Ice Build Up in Your HVAC System?
If you haven’t actually taken a look at your evaporator coil, or condensing coil, and you’re just wondering if you have ice build up, there are some tell tale signs.
One is lack of airflow at your supply registers. When you have a frozen evaporator coil, the blower fan won’t be able to push as much air across it.
Another symptom may be warmer air and low air flow. Even though your evaporator coil is a solid block of ice, evaporator coils are designed with a lot of surface area to maximize the amount of heat that can be transferred to the coil from the air.
Why is taking so long to just tell you why there is ice on your unit?
Ok, Ok, don’t rush me
Ok, so the most common reason for ice build up on your AC is a dirty air filter. Yep, your negligence is the reason why you’re hot and sweaty right now.
The first thing you want to do if you have ice build up is to turn the AC off, and check your filters. Replace your dirty filter (obviously).
Dirt blocks airflow. If there is low airflow across your ac’s evaporator coil, then there isn’t as much heat being transferred to the evaporator coil . This throws the whole system out of whack. The lack of heat being transferred to the coil causes ice build up and poor airflow into the home.
You need to let the ice thaw before turning your AC back on though. Run it in fan only mode to help the ice thaw quicker. YOU NEED TO KEEP AN EYE ON IT THOUGH TO MAKE SURE THE THAWING ICE WATER DOESN’T LEAK EVERYWHERE.
Once it’s thawed, you can turn your AC back on there should be cold air flow from your supply vents.
Dirty Evaporator Coil
Dirty coils have a similar effect to dirty filters. Evaporator coils can act as a filter when there is no filter, the filter is dirty, or there is a lot of filter bypass. They will catch all the dirt and dust that bypasses the filter.
It should be apparent at this point how important regular maintenance is. Both of these issues could have been prevented with regular maintenance.
If you’re handy you can clean the evaporator coil yourself. Again turn off the system and let it thaw. Spray the indoor and outdoor coils with coil cleaner sold at any home improvement store. Follow the directions on the can.
Too many closed registers
It is common for homeowners to want to save on their energy bill by closing off vents to unused rooms. This is generally a bad idea. Blocked registers build up pressure inside the air ducts and cause insufficient air flow.
I don’t think I need to explain how to fix this one, do I?
Dirty or Faulty Fan
If you’ve been following along closely, you should have realized that if there is not enough air flowing across the coil, it will ice up. Obviously a dirty, or broken fan will reduce air flow.
If it is broken, you have probably crossed from the DIY realm into the professional AC repair realm. Unless you are capable of testing and replacing fans and blower motors, you should leave this to the professionals.
This is probably worst case scenario. An AC system low on refrigerant is going to have all kinds of problems. One of them is definitely build up of ice on the coils.
The only way to address this to call a professional HVAC contractor to find the leak, repair, and add refrigerant.
If your system is older and uses r-22 refrigerant this is even worse. Older systems with a low level of refrigerant are not worth repairing. As of January 2020 it was illegal to produce and import this refrigerant.
Any of this refrigerant left is very expensive. A refrigerant charge is often more expensive than just replacing the unit.
Buildup of ice is bad and a sign that you need to service your system
Your AC needs proper airflow to work and insufficient airflow can wreak havoc on your system and wallet
You may be able to address the issue yourself, or you may need to call in a professional
Keep up with your maintenance and regular tune-ups to prevent bigger and costlier issues
It’s a good idea to keep a window air conditioner (or two) on hand in case of emergencies.
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