Why You Have a Frozen Air Conditioner and What to Do About It
By: Brian Schutt | July 18, 2016
A few weeks back, we shared in this space why a frozen air conditioner isn’t so cool for your home or your budget. There, we focused on potential issues within the unit that might cause a condenser to freeze.
But as the good guys at Ask This Old House point out in the video below, there may be another reason—the wrong-sized unit for your home.
How to Determine the Right A/C Size for Your Home
On the first Homesense in-home appointment, our design technician performs a full inspection of your house to determine the proper unit—including the inspection of ducts, windows and insulation and measuring and calculating the overall square footage and ceiling height, which allows for the industry calls a load calculation.
It gets pretty complicated after that—as many other factors can more accurately determine the proper size—but below’s a simple chart to help you quickly guess at the size you’ll need:
Square Footage
Capacity Needed
100 to 150 square feet
5,000 BTUs
150 to 250 square feet
6,000 BTUs
250 to 300 square feet
7,000 BTUs
300 to 350 square feet
8,000 BTUs
350 to 400 square feet
9,000 BTUs
400 to 450 square feet
10,000 BTUs
450 to 550 square feet
12,000 BTUs (1 ton)
550 to 700 square feet
14,000 BTUs
700 to 1,000 square feet
18,000 BTUs (1.5 tons)
1,000 to 1,200 square feet
21,000 BTUs
1,200 to 1,400 square feet
23,000 BTUs
1,400 to 1,500 square feet
24,000 BTUs (2 tons)
1,500 to 2,000 square feet
30,000 BTUs (2.5 tons)
2,000 to 2,500 square feet
36,000 BTUs (3 tons)
Why the Proper Air Conditioner Size Matters
In addition to potentially freezing out your system, a unit that’s too large for your house can actually do half the work it was designed to do. How so? Central air conditioners are charged with both cooling down your house and removing humidity. Oversized air conditioners cool your house down too quickly and, therefore, shut off before running an entire cycle. And as a result, they do not complete the second phase of demudifying your house.
And more understandably, if the unit’s too small it will run and run and run trying in vain to cool your entire home–causing it to
