If you’ve been considering a commercial HVAC maintenance agreement or you’ve scheduled a service visit and want to know what to expect, this guide is for you. Business owners often aren’t sure what a maintenance technician actually does during a visit — and that uncertainty sometimes makes the investment feel abstract. Understanding what’s covered during a professional commercial HVAC maintenance visit makes it easier to see the value and ask the right questions when evaluating service providers.

Smith Mechanical has been maintaining commercial HVAC systems across Whatcom County for more than 35 years. Here’s a detailed look at what a thorough commercial HVAC maintenance visit includes and why each element matters.

Filter Inspection and Replacement

Filter service is the most basic element of HVAC maintenance, but it has an outsized impact on system performance. Clogged filters restrict airflow through the system, reducing the efficiency of heat and cooling transfer, making the fan work harder, and in severe cases causing the system to overheat or freeze up. Commercial systems often have multiple filter locations — in air handling units, at return grilles, and in some cases in pre-filter stages before the main filtration media.

During a maintenance visit, technicians inspect all filter locations, note the condition of current filters, and replace them according to the service schedule. For businesses in settings with higher-than-normal dust or particulate levels — woodworking shops, bakeries, facilities near agricultural operations — more frequent filter service may be necessary, and a good service provider will tailor the maintenance schedule accordingly.

Coil Cleaning

The evaporator and condenser coils in commercial HVAC equipment are heat transfer surfaces — they’re how the refrigerant circuit moves heat in or out of your building. Dirty coils are dramatically less effective at heat transfer, which forces the system to run longer cycles and consume more energy to achieve the same result. Over time, heavy coil fouling can cause compressor damage from elevated operating pressures and temperatures.

Cleaning commercial coils properly requires the right equipment and cleaning agents. Technicians use coil brushes, foaming coil cleaners, and in some cases commercial pressure washing equipment to remove accumulated debris, pollen, grease film, and mineral deposits. Evaporator coils inside air handling units are cleaned carefully to avoid damage to the fin structure, while condenser coils — typically outdoors on rooftop equipment or in condensing unit enclosures — may have heavier debris buildup from exposure to the environment.

Refrigerant Level Check and Leak Inspection

Refrigerant is the medium that makes air conditioning and heat pump heating possible. A system with low refrigerant charge operates inefficiently, struggles to meet temperature setpoints, and places excessive stress on the compressor. Over time, continued operation with low refrigerant leads to compressor overheating and failure — one of the most expensive HVAC repairs there is.

During a maintenance visit, technicians check the system’s operating pressures and temperatures to evaluate refrigerant charge. If the system shows signs of low charge, they’ll investigate for the source of the leak — because refrigerant doesn’t get used up, it can only escape through a leak. Finding and repairing the leak is as important as topping off the refrigerant, as a system that keeps leaking will end up in the same position in a few months.

Electrical Component Inspection

Commercial HVAC systems have numerous electrical components that are subject to wear and failure — contactors, capacitors, relays, control boards, wiring connections, and motor windings. Many of these components can be tested or inspected to identify ones that are beginning to fail before they actually do so.

Capacitors, for example, can be tested with a capacitor meter. A capacitor reading significantly below its rated microfarad value is likely to fail soon and should be replaced proactively. Contactors — the electrical switches that connect line voltage to compressors and fan motors — can show visible signs of wear or arcing that indicate they should be replaced. Electrical connections that have loosened over time create resistance that causes overheating and can eventually lead to wiring failures or fires.

A thorough electrical inspection during a maintenance visit catches these warning signs while the equipment is still running, rather than after it has failed.

Lubrication of Moving Parts

Fan motors, bearings, and other moving components in commercial HVAC equipment require lubrication to operate correctly and avoid premature wear. Many modern motors are permanently lubricated and sealed, but others have ports designed for periodic lubrication. Technicians identify and lubricate all applicable components during a maintenance visit.

Motor bearings that run dry develop noise, heat up, and eventually fail — often causing the motor to burn out. Catching and addressing lubrication needs during scheduled maintenance is far cheaper than replacing motors and dealing with the collateral damage a failed bearing can cause.

Thermostat and Controls Verification

Commercial HVAC controls range from simple programmable thermostats to sophisticated building automation systems with multiple zones, demand-controlled ventilation, and remote monitoring capabilities. Whatever level of controls your facility has, verifying that they’re operating accurately and as programmed is an important part of maintenance.

Temperature sensors can drift over time, causing the system to heat or cool to the wrong setpoint. Programming can be inadvertently altered, leaving equipment running when it shouldn’t or failing to reach setback temperatures during unoccupied hours. Zone dampers can fail open or closed, sending conditioned air to the wrong areas. A controls verification during maintenance catches these issues that might otherwise quietly waste energy for months without anyone realizing it.

Safety Control Testing

Commercial HVAC equipment includes numerous safety controls — high-pressure cutoffs, low-pressure switches, high-temperature limit switches, combustion safety controls on gas-fired equipment, and more. These controls exist to shut the equipment down safely if an abnormal operating condition develops. If a safety control fails in the open position, the system may continue operating in a condition that could damage equipment or create a safety hazard.

Testing safety controls during maintenance verifies they’re functional, which is particularly important for gas-fired heating equipment. A failed limit switch on a gas furnace could allow the unit to overheat — a situation that can cause heat exchanger damage and, in extreme cases, pose fire risks.

Drain Pan and Condensate System Service

Air conditioning systems remove moisture from the air as part of the cooling process, and that condensate has to go somewhere. Commercial HVAC equipment includes drain pans and condensate drainage systems to carry this water away from the equipment. When these systems are neglected, drain pans can overflow, causing water damage to ceiling tiles, building structures, and equipment. Biological growth — algae, mold, and bacteria — can colonize drain pans and condensate lines, causing clogs and contributing to indoor air quality issues.

During a maintenance visit, technicians inspect and clean drain pans and flush condensate lines to ensure they’re clear and draining properly. Condensate overflow sensors — where installed — are verified to be functional.

System Performance Documentation

A professional maintenance visit doesn’t end with the last item on the inspection checklist — it concludes with documentation. Smith Mechanical technicians record the results of each maintenance visit, including measurements taken, components replaced, issues identified, and recommendations for future attention. Over time, this documentation builds a performance history for your equipment that helps identify trends and plan proactively for end-of-life decisions.

When a technician notes that a compressor’s operating temperatures have been creeping upward over three consecutive visits, that’s actionable information that allows you to plan for potential replacement rather than waiting for an unexpected failure.

Scheduling Your Commercial Maintenance Visit

If it’s been more than a year since your commercial HVAC systems were professionally serviced — or if you’re not sure when they were last maintained — now is a good time to get a visit on the schedule. Smith Mechanical serves commercial clients throughout Bellingham, Ferndale, Lynden, Blaine, Birch Bay, Sumas, and the rest of Whatcom County. Call us at 360-384-3203 or contact us online to schedule a commercial maintenance visit or discuss a maintenance agreement for your facility.