Service Clinic Extra: Commercial Split SystemComponent Maintenance

May 11, 2010
To protect performance during the cooling and heating seasons, split system components should be serviced twice a year, Lennox sources say.

Contaminant build-up and neglected maintenance are the two top causes of HVAC inefficiency and failure. Letting dust collect on coils and filters and delaying regular maintenance can lead to higher energy bills and service costs while compromising the quality of the building’s indoor air. To protect performance during the cooling and heating seasons, split system components should be serviced twice a year.

The experts at Lennox Industries offer this checklist for maintaining HVAC split system equipment.

Remove dust and grime
from evaporator and condenser coils. Dirty coils reduce the equipment’s ability to cool your building and cause the system to run longer, increasing energy costs.
Outdoor coils.
Turn off power to the unit. Remove any loose debris from the area, and flush the coil with a water hose. If the coil has a screen, wire cage or louvers and water alone won’t remove the debris, you must remove the top of the unit or open or remove louver panels. Blower components should be cleaned regularly and adjusted to maintain proper airflow for comfort and energy efficiency. Airflow problems can reduce system efficiency by up to 15%, according to ENERGY STAR®.
Air filters
should be inspected once a month during the operating season, and cleaned or replaced as needed. Dirty filters can damage equipment and cause it to run longer and draw more energy which may reduce equipment life. Inspect the condensate drain lines and drain pan and clear if necessary. A plugged drain can cause high humidity and may lead to leaks and water damage.
Heat exchanger,
furnace burner assembly and ignition system should all be inspected, and cleaned if needed.

Test thermostat settings to make sure heating and cooling turn on and off at the programmed temperatures.
Check equipment starting cycle to be sure the system start will operate and shut off properly.
Adjust refrigerant charge if necessary. An improper charge will cause the system to work harder and use more energy, as well as reduce the life of the equipment.
Tighten electrical connections and measure all motors’ current draw. Inspect the entire control box including contactors, relays, circuit boards, capacitors and other accessories for damage or wear.
Check for leaks in ductwork. Inspect fan motor and blades for damage, rubbing noise or vibration. Visually inspect connecting lines and coils for oil or refrigerant leaks. Be sure the flue system is properly attached to the furnace and repair any damaged parts.
Check heat exchanger for any signs of corrosion. Replace if necessary.

Adjust blower speed for cooling. Measure the pressure drop over the coil to determine the correct blower CFM stated in the unit’s service manual.
On belt drive blowers, check for any belt wear and replace annually or as necessary and adjust tension. If the unit is an older model that is not pre-lubricated and sealed, make sure all moving parts are fully lubricated. Otherwise, friction can increase energy usage.
While the system is operating
, monitor its startup and listen for any unusual noises or odors. Measure outdoor dry bulb temperature and indoor dry and wet bulb temperature across the coil.

To learn more about maintaining split system HVAC equipment, or about Lennox HVAC systems, visit or call 1-800-9-LENNOX.