Central Air Conditioner and Heat Pump Maintenance
The condensing unit of a central air conditioner or heat pump resides outside throughout the year and needs at least annual attention just as any other aspect of your home’s Heating, Ventilating and Air Conditioning (HVAC) system.
Annual maintenance should include:
- Cleaning dirt, leaves, and other debris from the condensing coils
- Checking condensing coil fins for damage
- Lubrication of fan bearings
- Inspection of fan for damage
Let’s review how to maintain a central air conditioner or heat pump condensing unit:
Needed Tools and Materials
- Phillips Head and Flat Blade Screwdrivers (if necessary to remove grilles)
- Small socket wrench or socket driver (if necessary to remove grilles)
- Adjustable Wrench
- Soft Brush
- Shop Vacuum
- Garden Hose and Spray Gun
- Fin Comb
Shutting Off Power to the Unit
Shutting off the power to the condensing unit will involve locating what’s called an electrical disconnect switch and turning off the 240-volt power at that point. The disconnect is a weatherproof metal box located near the condensing unit.
To turn the power off proceed as follows:
- Open the disconnect switch box and depending on its design, remove the power plug which activates the box, or turn the power off with the shutoff handle or remove the fuse plug.
- Also turn off the power to the unit at the main electrical service panel.
- Wait a few minutes before proceeding with any further maintenance steps. This will allow any stored electrical charge that may reside in the unit’s capacitors to dissipate.
Remove Protective Grilles and Lubricate Motor
To access the outside and inside of the condenser coil you must remove the protective side grille. You also need to remove the top panel that protects the fan, motor, and interior of the condensing unit.
To remove the grille proceed as follows:
- Remove the screws holding the side and top panels in place using a Phillips head, flat blade screwdriver or socket driver as required and place the screws in a secure area.
- With care, pull the side grill away from the unit and lift the top panel which may also support the fan motor.
- Carefully support the top grille with the motor and fan making sure not to stress any electrical wiring connections.
- Locate the fan motor oil ports above the fan blade and place a few drops of lightweight household oil into each port.
Clean Condenser Coils
Cleaning the coils of debris is the first step. When cleaning the coil fins, be careful not to bend them. You’ll be cleaning the coil from the outside and the inside. Once the power is shut off proceed as follows:
- Clean the outside of the coil of any sticks or debris.
- Vacuum the outside of the coil fins using a soft bristle brush attachment. You do not want to bend the fins when vacuuming.
- Once the outside is relatively cleaned, turn your attention to the inside of the condensing unit. Using a hose with a spray gun, spray water from the inside of the coils through to the outside of the coils which will remove stuck debris.
- Do not spray the fan motor or wires.
- Vacuum out or remove by hand, any debris that is littering the inside bottom of the unit.
- If your unit has no bent coil fins, then replace the grille covers. If your unit has bent fins, then proceed to the next step.
Straighten Bent Coil Fins
If your condensing unit has coils that are bent, they should be straightened out as much as possible for proper performance of the unit. You cannot straighten the fins properly without a special tool called a fin comb. These tools come in a variety of styles including single, multiple or interchangeable heads having different fin comb sizes and counts to best match the coil fin size of the repaired unit. Some six-sided head models will work for 8, 9, 10, 12, 14 and 15 fins per inch coils.
- To straighten the bent fins, match the teeth count of the comb to the fins per inch of the coil. Then carefully draw the comb across the bent coil fins straightening them out in the process.
- Replace the grille covers and screws.
Making Sure the Condenser Unit is Level
The condenser must be level for proper operation. If it is not, then problems with drainage and premature wear and tear will occur. To check for level, proceed as follows:
- Take a level and lay it on the top of the condensing unit in north/south and east/west orientations.
- The unit should be level in both orientations.
- If it is not, adjust the height and level the unit by adjusting the leveling feet or by shimming the feet with wood shims slightly to achieve level.
- If the unit is seriously out of level, then repair or replace the concrete slab block the unit sets upon.
Power On Sequence
To power the unit back on after it has been shut off more than three hours, proceed as follows:
- Switch the thermostat inside your house to the “off ” position.
- Restore power at the outside electrical disconnect box and service panel.
- Turn the thermostat to “cool” to power the unit back on.