The AC unit is an important aspect of indoor home comfort when the weather is hot outdoors. But, air conditioning systems will gradually lose efficiency over time, and this is equally applicable to the heating parts of an HVAC system. Regular preventative maintenance is the key to preventing much of the performance and energy efficiency losses. During maintenance, the HVAC technician will carry out some cleaning. Between these visits, you can clean the AC system yourself, following the steps detailed below.

 A  Brief AC Unit Primer

This is a lengthy process, and you will need around half a day to complete the cleaning. Certain aspects of the cleaning require precision and dexterity, and it’s easy to make mistakes if you don’t know what you’re doing. Some specialized tools are required before you get started to prevent unnecessary downtime.

The air conditioner has an indoor and outdoor component and each contains a different type of coil. The indoor element has an evaporator coil, which absorbs heat as the refrigerant evaporates from a liquid to a gaseous state. The refrigerant then transfers the warm collected air to the outdoor AC unit, where it passes through a compressor to the condenser coil. The compressor turns the refrigerant back to a liquid state, and the condenser coil releases the collected air with the exhaust fan.

To properly clean the AC system, the indoor and outdoor components must be cleaned, and this is a complex task. In summary, this task is best left to your local HVAC technician, but if you’re determined to go ahead, follow these steps in order for the indoor and outdoor unit.

The Indoor Unit

1.   Turn off the AC Power

Safety should be the primary concern. Turn off the AC system and the power at the breaker box. You will need light to work; if the indoor unit is an attic, you will need some additional lighting.

2.   Open the AC Unit

You may need to remove some foil duct tape to access the evaporator coil through an access door on the blower unit. There are likely to be some bolts or screws to remove to get the access door open.

3.   Clean Evaporator Coils

Remove the surface dust with a soft brush, and wear gloves and a mask as you clean because the dust will contain: bacteria, pollen, dust mites, and other contaminants. Then use a  no-rinse coil cleaner, spray the coils, and the foam will remove the remaining dirt and dust. Spray evenly and ensure that you get all those areas that are hard to reach by hand. The excess coil cleaner will drip into the drain pan, and from there, it will drain away. The ideal time to clean the evaporator coils is on a warm day because the AC condensation will rinse the coils clean when you turn the system on.

4.   Clean the Drain Pan

Use a 50/50 mix of water and unscented bleach and pour this solution into the drain to clear and sanitize the drain line. If this washes down easily, you’re ready to move onto step 5, but if the drain is sluggish, you may have a plugged drain.  A lack of regular preventative maintenance can cause clogs to form in the drain, which may contain algae and mold growth. Find the end of the drain line outside and use a wet/dry vacuum to suck out the clog. Create a tight seal around the vacuum and the drain line with duct taps to improve the suction. This takes 2-3 minutes to clean out the clog and other accumulated crud that may be lurking in the drain line. After the cleaning, you can pour a second bleach solution into the drain pan to sanitize the drain line.

5.   Finishing Up

Replace the access pane, screw it in place and seal the top and bottom with metal foil tape. Don’t cover the manufacturer label; this will be needed if an HVAC technician needs to maintain or repair the unit. Now it’s time to move to the outdoor unit.

The Outdoor Unit

1.   Turn off the AC Power

The power should still be disconnected, but if you’re cleaning the outdoor unit on a different day, turn the power off now.

2.   Remove the Cover

Most AC units have sheet metal screws to hold the cover in place; remove them and keep them safe. Lift the fan unit, remove the grille, and set the top aside against the wall. There should be sufficient slack, and the wires can stay connected.

3.   Clean the Debris

There will be debris at the bottom of the AC unit, including seeds, twigs, leaves, and more. Scoop this debris out by hand and use the wet/dry vacuum to get the smaller pieces.

4.   Clean the Condenser Coils and Fins

You will need a commercial coil cleaning solution that you can find at most home improvement stores. This is a caustic liquid that emits dangerous fumes, so wear gloves, a mask and goggles when you handle this cleaner. This product is only for the outdoor coils; if it’s used on the indoor coils, it will damage them, so take care. Follow the instructions carefully, put the solution in a pump sprayer and spray it on the coils. It will foam up; leave it for the required time and then wash it off with the garden hose. Don’t use a pressure washer for rinsing because it may damage the delicate fins.

5.   The AC Fins

Any bent fins will degrade the airflow; an inexpensive fin tool has teeth that you can use to comb the fins into their correct position. The correct number of fins per inch for the unit must be used to prevent damage.

6.   Clean the AC Unit Exterior

Replace the fan cage and cover with the screws and clear the area around the AC unit up to a distance of at least two feet. Move exterior furniture, tools, ladders, and other outdoor items to a better location. Trim back trees, shrubs, and other vegetation, and the airflow will be improved.

7.   Level the AC Unit

If dirt and debris under the unit have caused it to tip in one direction, it should be leveled now. If the AC system is not level for a prolonged period, it may fail earlier than expected, and there could be frequent repairs. Shims can be used to get the outdoor AC unit back to a level position.

If you want to schedule essential preventative maintenance and cleaning for your HVAC system, contact your local heating and cooling specialist today.