Why’s My Coil Freezing?

Well, it’s about to get hot in the beautiful Kentuckiana area. VanKleef Heating and Air Conditioning can assist.

When it gets hot, some of you will experience a frozen coil. The big line between the indoor and outdoor units is covered with ice. If you remove the coil panel, you would see a big blog of ice there as well. Next step is a big puddle of water under the furnace when you stop the unit from running.

So, what causes a frozen coil? Two things primarily cause it: low load and low refrigerant (R-22, R-410a, Freon, Puron, etc.) charge.

Low load. What is that? Well, it’s usually a dirty filter. That is why it is important to change your filters once a month. You can regulate this by one of your monthly bills. For instance, when you pay your cell phone bill, change your filter in your HVAC system.

The other cause: low refrigerant charge. Now, you may be thinking “when the refrigerant charge is low, the house gets hot. How can this possibly freeze the coil?” Well, here’s the answer.

Low refrigerant charge reduces the pressures of the indoor coil. The lower pressure corresponds to a lower temperature of the refrigerant as it enters the coil. The freezing process starts there. As the system runs and runs and runs, the ice builds and builds. It does take some time to build this ice block.

So, what causes a low charge? Two choices again: a leak or improper charge. All systems come charged from the factory with enough refrigerant for a 15′ lineset (the copper pipes between the units). The installing contractor has to add a certain amount of refrigerant for each foot of copper. If not, you’ll get a frozen coil when the unit runs long and hard in the first heat wave. The second would be if you have a leak. Replacing the Freon without fixing the leak would be like putting gas in your car knowing you have a leak, driving around and wondering why you are using so much gas. We can inspect your system, fix the leak and replace the Freon all in one call.

Well, I hope that you now understand a little better about the causes of a frozen evaporator (indoor) coil. If you have any questions, feel free to ask. Love to help you with questions 812-280-0510 – Werner VanKleef


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