Ice Ice…Maybe? A Frozen AC Unit Could Be a Sign of HVAC Problems

frozen ac unit

When was the last time you saw ice here in the Valley? You have to get up pretty early if you want to: Even when it freezes overnight, it often only does so in December and January, and it’s almost always melted by sunup! In fact, you might have a better chance of seeing frost in summer than in winter here. That’s because one of the most common places to see frost and ice is on your air conditioner when it’s running. We’ll tell you why you might be seeing ice or frost on your unit, and when you should call the HVAC guys.

 Frozen AC Unit: Why and When

You may see frost or ice in several places. The exterior AC unit is a common place, as are any lines going to or from it.[1.] And the interior AC unit may show ice as well. There are some simple physics at work, which boil down to this: if a gas expands and its pressure goes down, it will cool down–and cool down anything around it as well. The molecules move slowly because there’s nothing to stop them and because of that, the temperature drops. In this regard, molecules are a lot like people: They don’t get cold when they’re running around but as soon as they slow down the blood slows a bit and chill can set in.

That’s normal–in fact, your AC depends on just that happening! But that air shouldn’t expand too much, or depressurize too much. If it does, then something is out of whack–and the first sign of that will be the AC unit icing over!

It’s especially common if you use your AC later into the winter months, which we’ve all been guilty of from time to time. If it’s below 70 degrees out and you run the AC, there’s a much higher risk of the exterior unit icing over. It’s just the last nudge the system often needs.

Common–But Not Ideal

It’s not necessarily the end of the world; ice on air conditioner components is actually not uncommon, and it doesn’t necessarily mean your system is permanently broken or even damaged. That said, any time you see ice or frost on any part of your HVAC system, you should call your HVAC contractor. Frost is the warning sign of a host of problems that could be occurring, some of which are more serious than others.[2.]

If the unit isn’t able to move as much air as it needs to, this may cause the system to become chilled. After all, the whole point of an AC system is to cool air. But it shouldn’t be able to chill the air to below freezing, because the air should be moving out and warm air taking its place. If the flow is restricted, the cold air may stay too long and the system temperature will drop, allowing parts to freeze. This could be the result of mechanical failure, dirty filters, or improperly sized ducts. Freezing could also be the result of low freon levels. But no matter what the cause, ice can cause real damage to a system.

What to Do When Your AC Freezes Up

The first step is to turn off the air conditioning. That will prevent further damage while you take the next steps to get the system back on track. After you’ve turned the system off, take a look at the air flow. Are your filters filthy? Do you have a lot of vents shut off around the house? Try opening all your vents up around the home and change your filters. This will make a big difference no matter what, and just might solve the problem!

We’ve had clients whose systems iced over a lot and never bothered to get it looked at, and we’re always happy when we don’t find permanent damage. The fact is, though, the longer you let this go the worse it will hurt your system! A tune-up and recharge is a lot cheaper than a new air conditioner–take it from us!

Professional Help

Generally speaking, ice or frost on the AC unit means you need to give an HVAC pro a call. Sometimes the answer is as simple as filters or vents being closed, but usually it’s more in-depth than just that. The fact is, air conditioners shouldn’t freeze up if they’re operating correctly–and if they do, it means there’s a problem likely rooted in mechanical error of some kind. That’s where a great HVAC tech comes into play–they’ll diagnose the issue and give you a quote that will let you know what you’re dealing with!