With the Spring and Summer seasons just over the horizon, it’s a good idea to take a look at your AC unit to make sure all is in order before you have to start relying on it to keep your house comfortable.  Cleaning up your AC unit will not only save you money on energy costs, but it will extend the life span of your HVAC unit as well.


Step 1:

Turn off the power to the unit.  Locate the correct switch on your breaker box inside and also hit the main shut off box outside by the unit.  This will ensure that you don’t have any electrical accidents and will keep the system from kicking on while working on it.


Step 2:

Remove any rubbish located on or in your unit.  Using a screwdriver or wrench, remove the fan cage from the top of the unit.  By hand or with a shop vac, remove any leaves or other debris that has accumulated from the interior.


Step 3:

If you are using a shop vac, use the brush attachment to remove any outside dirt on the unit.  Next we will use a standard garden hose to spray both the inside and outside of the unit.  Never use a power washer when cleaning an AC unit, the pressure can damage the fins and reduce ventilation.  There are fin cleaning sprays available if you want to be thorough, but standard water from the hose will get the job done.


Step 4:

If your unit has bent fins then take the time to straighten them out.  Bent fins will reduce the efficency of your unit.  A butter knife has always worked well for me but any flat tool could get the job done.


Step 5:

Once you finish getting the top cage fascened back on, cut any vegetation in a 2ft radius around your unit.  This will provide optimal air flow for your unit, ensure top efficency.  It is recommended to cover the top of your unit with a piece of plywood in the winter months to keep debris out.  Do not cover the sides of the unit so moisture can be evaporated quickly to reduce corrosion.


Step 6:

Now we will bring our attention inside.  On the inside of the blower/furnace unit, find the evaporator coil.  Use a nice soft brush to dust it off and then spray on some no-rinse coil cleaner.  The foam from the spray will drip down in the the drain pan.  Take the drain pan out and give it a good cleaning.  You can put a drain pan tablet in the pan to prevent algal growth.


Step 7:

Check to see if your evaporator drain is plugged.  On the interior, warm, humid air from your home’s interior is blown through the evaporator coil. The cold coil absorbs heat from the air, cooling it, before the air is circulated back into your home. The humidity in the air condenses on the cool surface of the evaporator coil as liquid water, dripping into a pan below. From the pan, the water flows into a drain tube which is typically routed into a basement floor drain, utility sink, or outdoors.

Over time, algae and mold can build up and potentially plug the drain, so if the drain is either not flowing or flowing very slowly, it will need to be unplugged. A plugged drain can either cause damage by flooding onto the floor or, if the system is equipped with a drain float, cause the system to stop cooling in order to avoid flooding.

First, find the drain line where it leaves the evaporator coil enclosure. The drain is usually a one-inch PVC pipe. Follow it to the end where it drains. Often the line drains outside near the condenser unit, but it can also drain into a utility sink or basement floor drain or, in the case of attic units, down an outside wall.

Once located, use a wet/dry vacuum to clear the drain. It’s best to remove the paper filter from the wet/dry vacuum so as not to ruin the filter. Hold the hose of the wet/dry vacuum to the end of the drain line. You can use duct tape or simply hold a rag around the gap. Turn on the vacuum for 2-3 minutes then turn off. This will clear the drain of any growing biological matter.


Step 8:

The filter in your HVAC system should be changed at least twice a year; once just before the heating season begins and once before the cooling season begins. If you live in a particularly dusty area, you may want to change it more often. Always replace the filter with a new filter that has the same airflow rating. Be careful with air purifying or HEPA filters.  They can reduce airflow in the home and cause the coil to freeze.

Locate the filter enclosure on the indoor furnace/AC where the large fresh air return duct enters the unit. You may need a screwdriver to turn the latch to open the door to the filter enclosure. Remove the old filter and install the new filter, matching the air-flow direction arrows on the filter to the arrows on the unit. Close and latch the door.


Step 9:

Just as easy as the first step…. turn the power back on in both the outside and indoor locations.


Now your AC unit is ready to run with high efficency.