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Ice on the AC Coil: Why This Shouldn’t Happen

In our last blog postice-on-glass, we explored some issues that can affect an air conditioning system over the summer. Knowing the ways an air conditioner might break is an excellent way to both catch problems early and possibly help prevent them from happening in the first place. Nothing is better at problem prevention than regular maintenance service, and it’s still not too late to have it done. Sign up for maintenance in Paramus, NJ or elsewhere in the Tri-State area today.

In this post, we’re going to look at a specific symptom of air conditioning troubles. It’s one of the most frequent warning signs something has gone wrong with an air conditioner, but it’s also one that leads to some confusion: ice along the indoor evaporator coil.

Why Ice Isn’t Normal on an AC…

The confusion people often have about seeing ice on an air conditioner is that it seems like it’s normal. Cold air comes blowing from the vents in the house when the AC is running, so why shouldn’t there be ice somewhere in the system?

This comes from a misunderstanding of air conditioning operation. An AC doesn’t use ice to cool down air. What it does is shift heat from inside the house to the outside using refrigerant, a process called heat exchange. The refrigerant is cold when it passes through the indoor coil, but it draws heat from the air through evaporation, and this warms up the refrigerant. After passing through the compressor, the hot refrigerant releases heat outdoors and cools down. If the air conditioner is working properly, no ice will form during this process.

…And Why It Might Form Anyway

What can go wrong with an air conditioner that will cause the growth of ice? The basic reason for ice to appear is that the refrigerant in the coil isn’t warming up and is remaining at sub-freezing temperature. The moisture along the evaporator coil will then turn to ice—and the ice will make it harder to absorb heat, leading to further ice.

There are a couple of reasons why the refrigerant might remains too cold in the coil:

  • There isn’t enough refrigerant: The refrigerant in an AC should remain constant through the system’s lifespan. But leaks can happen, and if there isn’t enough refrigerant moving through the coil, it won’t be able to effectively absorb heat—leaving the remaining amount too cold. This needs repairs right away to seal leaks and recharge the refrigerant, otherwise the whole AC is in danger of a catastrophic breakdown.
  • The air filter is clogged: A clogged filter will cause numerous troubles for an air conditioner, such as preventing enough warm air from crossing over the coil to warm up the refrigerant.
  • The coil is dirty: A layer of dirt and grime over the coil creates an insulating layer preventing the refrigerant from absorbing heat properly.

Regardless of the cause of the ice on the coil, don’t attempt to chip or scrape it off on your own. This doesn’t address the cause of the problem, and it risks doing damage to the coil and fins. Call for HVAC professionals to do the necessary repairs.

Advanced Mechanical Services offers air conditioning repairs 24/7 throughout the Tri-State Area.

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