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Whether you have a whole-house or one-room air conditioner, don’t make it work harder than it should. Follow these tips for keeping your AC running smoothly, so your home will stay cool all season long.

1 / 21

Understand How Your Air Conditioner Works

Most central air conditioners have two basic parts: an outdoor unit (compressor/condenser) that sits next to your home and an indoor unit (evaporator) that’s located in a central duct near your furnace. If you have a heat pump instead of a furnace, the indoor unit will be in the air handler. Use the same maintenance steps we show here. If your furnace looks different from the one shown or you have a heat pump, use the owner’s manual to find your way around it. The basic parts will be the same.

2 / 21

fixing ac fins with butter knife

Fix Fins in the Condenser

Realign bent or crushed fins with gentle pressure from a dinner knife. Don’t insert the knife more than 1/2 in.

3 / 21

vacuum air conditioner

Keep it Clean

Cleaning an air conditioner in the spring, before you start running it, will help it perform better through the dog days of summer. To start, vacuum the fins of your AC unit clean with a soft-bristle brush. Note: they’re fragile and can easily be bent or crushed. On many units you’ll have to unscrew and lift off a metal box to get at them. Check your owner’s manual for directions and lift off the box carefully to avoid bumping the fins.

4 / 21

sinking air conditioner pad

Fix a Sinking Home Air Conditioner Pad

The concrete pads under home air conditioner and heat exchanger units tend to settle over the years. As long as there’s no strain on the copper coolant tubes and electrical lines, and the unit stays dry and level, it’s OK that the pad has sunk. But if it continues to sink and pulls the lines tight, or if water puddles around the unit, you’ll need to fix the sinking air conditioner pad.

5 / 21


Get a Programmable Thermostat

A programmable thermostat is a must-have in today’s state of AC technology. Programmable thermostats allow you to set temperatures for various times throughout the day and automatically lower the temperature when you most need it to help you save money and manage your cooling without constantly hovering over the dial. Installing a programmable thermostat is an easy DIY task you can complete in less than a day.

6 / 21

duct booster for AC

Add an In-Line Duct Booster for Home Air Conditioning Units

If you have forced-air cooling but there’s still a room that’s hotter than all the rest, a duct or vent booster fan can increase the flow of cool air into that room. Two types of booster fans are available. An in-line duct booster fan (shown) fits inside the duct of the room you’re trying to cool. You mount the fan near the outlet and it automatically kicks on when your cooling system runs.

Vent and register booster fans sit directly on top of or replace ceiling, floor or wall registers. Depending on the model, you can set it to operate automatically, control it with a switch or operate it by a remote control.

7 / 21

noisy air conditioner fix

Quiet a Noisy Air Conditioner

If you already have a newer condenser, the worst noise is probably coming from the compressor. (Fans on newer units are very quiet.) One of the most common fixes for a noisy air conditioner is a sound blanket. Contact the manufacturer to find a sound blanket for your model or buy a universal blanket. Installation is easy. Don’t bother putting a blanket on an old unit—you’ll still hear the noisy fan.

8 / 21

Unclog the Condensate Drain Tube

When you see water puddling around the furnace with the AC running, you have a clogged condensate drain tube. Condensation from air conditioning coils contains bacteria that can form slime and clog the condensate pan drain tube.

9 / 21

air conditioner outside of house

Warm Season Checklist

Make sure your AC is in good working order to keep you cool. When it gets hot outside, you want it to be nice and cool inside your home. Use this handy inspection checklist to assess your HVAC system and then schedule an appointment for any needed AC maintenance or repairs before summer heats up.

10 / 21

change furnace filter

Replace the Filter

Turn off the power to the furnace at a nearby switch or at the main panel. Then pull out the furnace filter and check it for dirt buildup. Change it if necessary.

11 / 21

air conditioner with landscaping

Is Your AC Unit the Right Size?

AC units are carefully sized to the amount of cubic feet they need to cool. That’s particularly important when you are purchasing a new AC unit or renovating your house. If an AC unit is rated for a smaller space than you have, it will work too hard to cool the air, wear out more quickly and struggle to meet the demands of the thermostat. Looking for a sustainable option?

12 / 21

whole-house fan

Consider a Whole-House Fan

Whole-house fans have helped cool homes for a century. The basic design is simple: An attic-mounted fan pushes hot air out through attic vents and draws cooler, outside air in through open doors and windows. This rapid air exchange—large fans can purge a house of hot air in two to three minutes—not only removes built-up heat but also creates a pleasant breeze.

13 / 21

Forgetting About Your Windows

Control Heat Through Windows

A lot of heat enters the home through windows, especially open windows. If you really want to control heat in your house, pay attention to your windows, too. Keep them closed and covered with blinds or drapes during the hottest parts of the day—especially windows that are currently facing the sun.

14 / 21

opening top of air conditioner

Troubleshoot Repairs Yourself

When central air conditioning service fails during a heat spell, you may have to wait days for an HVAC repair technician to show up, and you’ll probably pay at least several hundred for the repair. But if you’re comfortable working around electricity and are willing to spend about $50 on parts, you can probably repair your air conditioner yourself in about two hours and save a lot of money on parts markup and labor.

15 / 21

insulation around outdoor AC lines

Check the Insulation

Condensation that forms on your outdoor AC lines reduces efficiency and raises your energy costs. But you can improve your unit’s efficiency by replacing insulation that’s damaged or rotted around your outdoor AC lines.

16 / 21

fin comb for air conditioner maintenance

A Fin Comb Comes in Handy

Fin combs work perfectly for separating bent fins on a small room air conditioner. Be sure to wear gloves to protect your hands from getting cut!

17 / 21

cleaning window air conditioner

Deep Clean with a Brush

Scrub crud off of a small room air conditioner using a plastic bristle brush and foam cleanser.

18 / 21

room air conditioner in trash can

Time for a New Unit?

Don’t just assume you can toss your old AC unit in the trash. There are likely rules about proper disposal in your city. Contact your local waste management organization to dispose of your AC unit properly.

19 / 21

room air conditioner in garage

Simple Way to Cool Your Garage

Don’t let summer heat slow down your DIY projects. Keep cool in your garage workshop by installing a room air conditioner. It’s easy to do yourself.

20 / 21

Find Air Leaks in Your Home

Close all the windows in the house, turn off all the fans and exhaust fans, and shut off the furnace. Light some incense and walk slowly around the outer walls of the house. Anywhere you notice the smoke blowing away from something or being sucked toward something, there’s probably an air leak. Now that you’ve found it, seal it! Here’s how.