How to Service and Maintain Your Air Conditioner

hands with screwdriver working on air conditioner
  • 1-2 hours
  • Beginner
  • 15-50
What You'll Need
Garden hose
Fin comb
Dust brush
Fan motor oil (specified by your manufacturer)
What You'll Need
Garden hose
Fin comb
Dust brush
Fan motor oil (specified by your manufacturer)

A good air conditioner maintenance routine will save you money while keeping you cool. For many folks, air conditioner service is critical to summer comfort, and even survival.

While significant AC service repairs are best handled by professionals, many basic fixes and regular maintenance tasks are easy once you understand the systems. Keeping your maintenance on a regular schedule will help you keep your home a comfortable oasis away from the heat.

Understanding the Important Parts of Your Air Conditioner

Whether you have a window AC unit or are one of the lucky homeowners to possess central air conditioning, some essential parts are included in every AC system to maintain cool comfort during the hottest days.

If you need to order replacements, you can usually find what you're looking for at your local hardware store, heating and cooling supply store, or online. When you order your parts, you double-check their compatibility with your system.

Condenser Unit

The condenser unit of your AC system will house many of the other components. It's a bit like the tower on your desktop computer, and you'll find nearly all the moving parts for your air conditioning system within this unit.

Air Compressor

This part of the system uses compressed air to move the refrigerant from its internal components out to the outer sections through the condenser coil, lowering the air temperature before pumping it back into your home.

Condensing Coil

The condensing coils move the refrigerant through the system allowing it to expand and cool. The fans blow the warm internal air over the coils, creating condensation, while the now cool gasses continue to flow through the coil.

Fan and Belts

The fans are the number one cause of issues cooling your space. Without the movement of warm air out and the cool air in over the condensing coil, the air conditioner wouldn't be able to cool the building.

If your fan belts are loose, frayed, cracked, or stretched, they'll cause the fan to work less efficiently and reduce the air conditioning unit's ability to cool your home.


person holding air conditioner filters

Air filters help keep outdoor pollutants out of your home by filtering them out as the warm inside air is pushed out and the outside air is brought in. Pollutants can be things like dust, pollen, smoke, and exhaust from the neighborhood cars. Air filters are the easiest part of the system to check and change.


The central thermostat controls the temperature inside your home. This device directs your air conditioner to work harder to cool a space or ease down and let the ambient air warm the room a bit. Most modern thermostats are digital, and the programming can cause issues if not up to date.

Air Conditioner Maintenance Checklist

Clean the Vents

Before you start your AC for the first time in a season, you'll want to ensure all the vents are cleared of dust and debris. A vacuum hose can help with this process, and wipe down vent faceplates with a damp washcloth.

Avoid using cleaning chemicals, as they can damage your system's filter, belts, and moving components.

Clean the Filters

hands holding clean air conditioner video

You should clean your filters every 12-18 months. You can run the filters under gentle warm water with some mild soap, rinse them clean and let them dry before putting them back in. While you've got the system open, wipe down and gently vacuum the condenser coil and housing.

Fix Drip Pans

Not all AC units will have a drip pan, but they should have one way or another to divert the condensation away from your home's foundation. The act of blowing warm air across the condenser with the coolant will cause the moisture in the air to condense into water on the pipes, and this water drips into a pan or a diversion pipe to drip outside.

If you need to repair your drip pan, the cost can be prohibitive to hire a professional when the job is relatively easy. With some time, a washcloth, and some silicone caulking, you can have the pan fixed and in working order in an afternoon.

Check the Belts

Replacing broken and frayed belts will prevent the AC unit from busting during the summer heat. Like the motor belts in a car, these are critical for cranking the fan and moving air across the condenser.

In the summer, this part is harder to come by, as it's one of the parts that are often overlooked, so they are in higher demand when they break mid-season. Adding this maintenance step to your annual checkup will prevent emergency runs to the hardware store when the thermometer reaches highs.

Check the Fans

air conditioner in need of repair

The fan or blower is a critical part that can cause mild inefficiency or catastrophic failure of your AC system. Without a properly working fan, your system can't exchange the air across the condenser, therefore can't cool the air, and once it's created the cool air, it won't be able to push that air into the building.

Ensuring the fan isn't chipped, cracked, or bound at the motor will help you prevent motor burnout and overheating. A broken fan doesn't push air or maintain balance, and you should replace the fan if there is any damage to the blades.

If there is string, hair, or excessive dirt and dust around the motor housing, take the time to clean it out with a damp cloth and vacuum.

Lubricate the Fan Bearings

You may want to dab a bit of mechanical oil into the bearings that the fan spins on but check on the manufacturer's instructions first. A dirty or bound fan motor can cause condenser issues, burnout, belt damage, rattling, etc. Keeping it clean will prevent most of these common issues.

Common Air Conditioner Problems

person holding air conditioner system for repairs


The condenser coil naturally creates water, which can pool and leak if the drip pan or diversion pipe isn't properly installed or repaired. Identify the leak, and the fix should be pretty evident. The fix may be more complex if the air conditioner is leaking other liquids or gasses.

Weak Blowers/Fans

As mentioned in the preventative maintenance section, fans can get gummed up and cause overheating and burnout in motors. You might be able to repair them by taking them apart for cleaning. If they're damaged, though, you'll probably have to replace them.

Low Freon

If you've ever heard the term "recharge your air conditioner," the person who said it was likely referring to adding the refrigerant to the system. While Freon isn't a gas that tends to escape the way many others do, it can leak slowly over time and reduce your air conditioner system's ability to cool the air.

This task can seem overwhelming, but once you look inside the system, it's a relatively easy project to finish. However, replacing your own freon is also illegal in many places, since it's a dangerous material to handle, and it's also a controlled substance.

Because it's both an environmental hazard and a dangerous drug, freon is declining as an AC coolant, and will eventually be replaced by a refrigerant called Puron.

Excessive Noise

If you're getting a lot of noise from your window AC unit, it could be several causes. Anything from a damaged or gummed-up fan to the mounting bracket not being correctly aligned and causing a rattle.

Start by checking for proper installation, and then continue troubleshooting by checking the fan, belt, and condenser coil. Sometimes the fix is as easy as wiping the parts down and vacuuming any dust bunnies.

Mold and Pests

Over the winter, you can develop mold, mildew, and other microorganisms in your air conditioner unit if it isn't properly winterized. To prevent this, remove your system from the window for the winter, or cover it with a weatherproofing plastic cover to prevent sitting water and weather damage.

In some environments, pests like bees, wasps, hornets, and other creepy crawlies can choose your air conditioner as a landing pad and base for their home. Part of it is the shelter it provides and the water created by the condenser process.

The only way to prevent pests is to identify the cause and eliminate the possibility of new infestations. Clear out the debris built up in and around the air conditioner unit. Using an air compressor and shop vac, remove all the little pieces of dust and bug parts around the condenser.

Place a small pest trap related to the pests you're dealing with within the system, and close it up. Ensure the space you put in the trap isn't going to get disturbed by moving parts within the system.

Clogged Drain

Relating to the leak issue mentioned above, your system should divert that condensation outside and into the ground near the home. Many people use this diversion to water plants or top-up water features in their landscaping. If there is no drainage, it's relatively straightforward that there's a clog in your drain.

You can start the troubleshooting process by locating your external drainage pipe. Do your best to clear out the tube from the outside, and try the system. If it starts dripping in the first 5-10 minutes, you've solved the clog.

However, you'll need to clear farther up the drain and prevent future clogs by adding this step to the annual maintenance routine.

Preventative Maintenance and Cost Cutting Tips

Install the AC System in the Shade

air conditioner compressor in shade

You can save a lot on the energy costs to run your system by installing your air conditioner condenser unit in a shaded area or undercover from the direct sun. When the condenser works extra hard to cool the pressurized freon, you're burning electricity and racking up those kilowatts.

Clean the Spaces around the AC Unit

When debris gets into the filters, drains, and fans, it promotes pests, causes mold and fungus, and encourages rodents and insects. Add a deep cleaning to your annual maintenance routine and light cleaning every month through your warmest season.

Cover Your AC Condenser Unit

Protect your external HVAC unit during the off-season to prevent damage from harsh weather and kids playing near it and keep debris and pests out of the system. When you prevent damage, you save money and time on future repairs.

Schedule Your Maintenance

Upkeep your AC as part of your spring cleaning routine, and you'll ensure your air conditioner lasts far longer than the base warranty. An average DIYer can do most tasks with an HVAC system with a bit of research, but some jobs may require the help of a professional technician.

Don’t Forget to Winterize Your AC System

Since water can pool and collect in and around the pipes in your AC unit, you'll want to ensure you drain it, dry it out, and cover it adequately to prevent freezing and potentially cracking lines.

Suppose it's a central air heating and air conditioner. You won't need to worry about winterizing, but if you have a window unit, a specific cooling system, or a swamp cooler-based air conditioner, winterizing is a requirement.

When to Call an HVAC Specialist

While most tasks in this home maintenance project are at a DIY level, there comes the point when you should call a specialist to avoid significant (and expensive) problems in the long run.

Consider calling an air conditioning servicing professional when the situation involves electrical wiring or replacing a major component. Tasks you should call an HVAC tech for include:

  • Replacing a burnt-out motor, air compressor, or condenser coil
  • Replacing or repairing ductwork and piping through walls and other building structures
  • Any work that has to do with electricity or connection to plumbing or natural gas

Your family's safety is more important than saving a buck or two. An improperly repaired AC unit can cause electrical shorts and spark fires. Some air conditioner repairs can void warranties and reduce the coverage of your homeowners' insurance cover damages caused by malfunctions.

Consistent checkups and maintenance will prevent frequent repairs, reduce the cost of professional attention and excessive energy, and keep your air conditioning system operating in tip-top shape.

How to Service and Maintain Your Air Conditioner

How often do AC units need to be serviced?

On average, you should have your AC unit serviced about twice a year. A good rule of thumb is to have it serviced once in the fall and once in the spring, at the end and the start of the summer season when you're using the AC all the time.

During this regular maintenance checkup, the service technician will make sure the unit is clean, that all the parts are in good working order, and that the unit is operating properly.

How often should you clean your outside AC unit?

Clean the outside AC unit twice a year, once in spring and once in fall. This will help prevent clogging that can compromise the unit's cooling power.

How often should AC filters be changed?

Your AC filter should be changed often to help prevent hair, dust, and debris from getting into your HVAC system and keep the AC functioning at its peak. Change this filter every 45 to 90 days to keep your AC working at max efficiency.

How often does Freon need to be added to AC?

Freon is the cooling fluid that essentially creates the chilly air that is emitted by air conditioning systems. You will need to replace this fluid in your system every two to five years.

Only a professional can replace the Freon in your unit. This fluid is dangerous to work with and there are strict federal regulations in place for handling Freon, so this is one task you cannot perform as a DIY.

What happens if you don't clean your AC?

If you aren't cleaning your AC, it's going to be affected by dirt, dust, hair, and grime. This will keep the AC from providing the cool air you want and make the AC work a lot harder, which only burns more fuel.