Like any mechanical system, air conditioners (AC) need regular care to run smoothly. Luckily, air conditioner maintenance includes many tasks you can tackle on your own. In this guide, we go over the specific types of maintenance a residential air conditioner needs along with tips for taking care of this important home system.
What Maintenance Does an Air Conditioner Need?
We asked This Old House plumbing and heating expert Richard Trethewey to share his air conditioner maintenance tips for central air and window units.
1. Change Your Filters
Dirty filters kill your AC’s efficiency, so it’s best to install a new one every month during the cooling season for central and window units—or clean them if you’ve got the washable type. “You can’t change them often enough,” adds Trethewey.
Look for the filter’s minimum efficiency reporting value, or MERV, which ranges from 1–12 for home AC units. The higher the number, the better filtration it provides.
2. Fix AC Leaks
Ducts can lose up to 30% of airflow through leaks, and window AC units are notoriously tough to seal properly. You can find leaks using the old “smoke trick.” For window units, light a stick of incense and hold it where the unit and the window frame meet. For central AC, hold the stick near duct connections. If the smoke blows around, you’ve got leakage.
For ductwork, use foil tape to seal small gaps and duct mastic for larger ones. For window AC units, stuff foam between the device and the window frame with tape as needed.
3. Use a Timer
There’s no need to blast the AC at full tilt while you’re at work. For central units, install a programmable thermostat that lets you set higher temps when you’re gone and cooler temps when you’re home.
Newer window units have built-in timers and adjustable thermostats, or you can buy a timer at any home store for $10—$20—just make sure it matches your device’s voltage. Unless you’re going on vacation, don’t shut off the system. Otherwise, the air compressor will need to work harder to cool your house later.
4. Insulate To Keep Air Cool
Another AC tip is to keep your ducts insulated. “When ducts run through an uninsulated attic or crawl space, all that expensive conditioned air inside them warms up, and the likelihood of condensation collecting on the duct walls skyrockets,” says Trethewey.
Wrapping ducts in hot attics or crawl spaces can help keep the air within them cool. You can use spray foam, batt insulation, or rigid-foam insulation. Seal batt and rigid insulation with foil tape—not duct tape. For tight spaces, wraps like Reflectix offer some degree of insulation.
5. Service Your Compressor or Condenser
A central AC system’s air compressor and condenser are usually located outside the house close to your foundation. This component works best when there’s about 24 inches of clear space in all directions, so get rid of nearby shrubs, tall grass, leaves, and hanging branches.
6. Keep Your AC Unit Cool
Extend the life of your AC system by keeping blinds or shades down during the day. You can also install awnings to shield south-facing windows from intense sun. Consider running the AC alongside floor or ceiling fans to circulate cooled air more effectively.
7. Perform Annual AC Maintenance
The contractor who installed your central AC can help put you on a yearly cleaning schedule that goes beyond just cleaning the filters. Schedule this checkup before the cooling season starts and make sure it includes the following tasks:
- Cleaning and inspecting coils
- Cleaning or replacing filters
- Adjusting and replacing fan belts
- Lubricating motors and bearings
- Cleaning and checking blowers and fans
- Inspecting controls and safeties
- Checking refrigerant and pressures
- Verifying operating temperatures.
8. Get Airflow
Shutting too many interior doors causes central AC systems to go out of balance, meaning there’s less airflow in the entire house. If you want some privacy, keep doors slightly ajar instead.
9. Upgrade for Efficiency
Federal laws require AC units to operate a lot more efficiently than they did a decade ago. For central AC, look for the seasonal energy-efficiency ratio (SEER) ratings to determine efficiency. For window units, the efficiency measure is called the “energy-efficiency ratio,” (EER). Current standards mandate a SEER rating of 13 and an EER rating of 8, but units with higher numbers should cost less to operate.
Bonus: Consider a Home Warranty
Looking for financial protection if your cooling system suddenly stops working? A home warranty may help.
