When Do I Replace My AC Unit?

ac in backyard

The central air system is a simple pleasure of everyday life. Your home should be a place where you can relax. On a 90-plus degree summer’s day in Missoula, MT, cool air is essential to your relaxation. If you take good care of your AC unit, with annual inspections and monthly filter swaps, it should last 10-15 years.

“How do I know when to replace my unit, or just have it repaired?” is a question we’re frequently asked at Design Air. 

We’ve identified three key factors you should keep in mind to inform your decision: Humidity, Age, and Temperature (or H.A.T.). 


Besides keeping you cool, air conditioning acts as a humidity regulator. If you notice that your house is too humid, your AC might not be doing its job properly. This, especially combined with other symptoms, may mean it is beyond repair.


Just like a car with high milage, an older air conditioner tends to run less efficiently, and may need increasingly frequent repairs.

If you find that your AC unit is incurring extra costs (increased electric bill, increased repairs) it may be time to replace it soon. If it needs to be repaired annually, it might not need to be replaced right away, but it’s definitely a sign that its expiration date is approaching. 

It’s important to be wary of how your AC unit is holding up, and how much money it’s costing you. An old system that frequently falls into disrepair may end up costing you more than a new unit in the long run, and won’t cool your home properly.

Replacing your unit will save you money in the long run, improve the air quality of your home, and reduce your carbon footprint. 


Pay attention to the stability of the temperatures in your home. Temperature inconsistency doesn’t always mean your AC unit is totaled. But, if your unit is older and you’re experiencing erratic changes in the air temperature, it may be time for you to replace it.

Call Your AC Professionals Today

Our team of trusted professionals at Design Air can give your underperforming HVAC unit an honest diagnosis. We’ll be able to tell you whether replacement or repair is a better choice. We take pride in helping our customers find the best option for a fair price. We’re just a phone call away at 406-251-7997.

Need HVAC Service?

Contact the experts at Design Air.

Call us at 406-251-7997!