Calgary winters are long enough that most commercial cooling systems sit idle for five or six months. When spring hits and temperatures start climbing, turning on the AC for the first time is where a lot of problems surface. Compressors that were fine in October may not start cleanly in April. Coils that looked passable last fall are now packed with a winter's worth of debris. Controls that lost programming during a power event have been sitting wrong for months.
A spring startup is not about finding problems for the sake of it — it is about catching the easy stuff before it becomes an expensive mid-July emergency when every HVAC company in the city is booked out.
Clean the condenser coils
This is the single most impactful thing you can do for a rooftop unit or split system heading into summer. Condenser coils collect dust, cottonwood, grease exhaust, leaves, and general debris. A dirty coil forces the compressor to work against higher head pressure, which reduces cooling capacity and increases energy costs. In severe cases it causes the compressor to overheat and shut down on safety.
On rooftop units, the condenser coil is usually accessible through removable panels. If you can see matted buildup on the coil surface, it needs cleaning. A proper coil wash with the right chemical and rinse pressure makes a noticeable difference in performance.
Check and replace filters
Air filters should be checked at every seasonal changeover. A restricted filter reduces airflow across the evaporator, which can cause icing, poor comfort, and higher energy use. In restaurants and retail spaces where foot traffic and cooking generate more particulate, filters may need replacement more often than the manufacturer suggests.
Inspect belts and blower components
Belt-driven blowers on rooftop units can develop cracks, glazing, or stretch over the winter. A belt that was borderline in the fall may snap on the first hot day when the system runs continuously. Checking belt tension and condition takes a few minutes and prevents a no-cool call later.
While you are at the blower, check the motor bearings and the wheel for buildup. A dirty blower wheel reduces airflow just as much as a clogged filter.
Verify thermostat and controls
Programmable thermostats and building management systems can lose schedules during power events or seasonal shutdowns. Confirm that the system is set to cooling mode, the schedule matches current occupancy, and the setpoints are reasonable. If you have a staged system, make sure all stages are enabled and responding.
Test the system before you need it
Run the cooling system on a mild spring day when you do not actually need it. Let it run for 20 to 30 minutes and check that cool air is coming from the supply vents, the compressor is running without unusual noise, and the system cycles off when the setpoint is reached. Finding a problem in April gives you time to schedule a repair on your terms instead of scrambling in a heat wave.
Check refrigerant lines and electrical connections
Refrigerant leaks do not fix themselves over the winter. If the system was low on charge last season and was not repaired, it will still be low. A technician can check pressures and identify leaks before the system is under full load. Electrical connections can also loosen over time due to thermal cycling — a quick tightening pass on contactors, terminals, and capacitor connections reduces the risk of intermittent failures.
Schedule maintenance before the rush
The best time to book a spring AC startup is before everyone else does. By mid-May, most HVAC companies are deep into cooling-season service calls and availability tightens. Getting ahead of that curve means better scheduling options and less downtime risk.
YYC Mechanical provides seasonal startup and commercial HVAC maintenance for Calgary businesses. If your rooftop unit has not been touched since last fall, now is the time to get it checked.