How could there be ice forming on our AC unit at this time of year?

Dear Doctor,

My husband and I live in a detached 1800 sq ft home in Streetsville. It’s our little nest–we’ve lived here for the last 10 years.

Of course, homeownership does come with its ups and downs. That being said, we’ve been quite lucky with our heating and cooling since we moved in  – until recently! The other day I was out in the backyard watering my flowers, and as I was pulling the hose around our central air conditioner, I saw something white growing around the line connecting it to the outside wall of our home. At first, I thought it was some kind of fungus, but would you believe it, it was ice on the lines going into the house! On a beautiful 25 degrees day! My jaw nearly dropped. If I was already sweating under my sun hat, I couldn’t imagine how there could be ice forming on our AC unit at this time of year. Also, our Central AC has a 10 SEER rating if that helps at all.

We could really use an expert’s opinion, so we can fix this problem!

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Hey Maggie – thanks for reaching out to us.

HVAC Expert, Andrew

There could be a number of reasons why you’re having problems with your A/C system, and it’s always best to have a qualified professional take a look. That being said, let’s go over a few of the possible issues. 

First of all, visible ice build-up on your Central AC (especially in the warmer months) is a problem that should get looked at right away. The ice build-up is a symptom of an improperly working unit, and you’ll probably notice your house isn’t cooling down like it used to (or in severe cases, not at all).

There are two main reasons most Central AC systems form ice. They either have (1) a clogged filter, or (2) a leak somewhere. A clogged filter in your coil unit (usually on the side of the furnace) is something you can probably locate and resolve on your own. A leak, however, can lead to low refrigerant and you’ll need an HVAC professional with special testing tools to properly fix the issue.

Clogged filters are relatively easy to change and keep clean. Get in the habit of performing a visual inspection every month, and replace the filter when it’s noticeably full of dirt, hair, or other debris. Guidelines vary, depending on the type, size, and quality of filter you have, but it’s generally recommended to change them out every 30-60 days or so. If you don’t feel comfortable with this, usually most HVAC maintenance plans include this as part of their check-ups.

If we do find a leak and are able to fix it, you might be able to simply replace the refrigerant, as long as your Central AC runs on the newer R410A type. If it’s 10 years or older and your system runs on R22, unfortunately, a repair is not available. Canada (and most countries around the world) stopped producing R22 because of its harmful effects on the ozone.

It sounds like your specific unit is running with a 10 SEER rating (Seasonal Energy Efficiency Ratio).  Without knowing the full details, it may be time for an upgrade. Like cars, the SEER deteriorates over time without regular annual maintenance. This causes your AC to use more energy in order to run, and also take longer to cool your house down. As of 2022, the Canadian standard is 13 SEER (which is more efficient and will save you money) and some units run as high as 22 SEER.

Hope this helps, Maggie!

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