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Peak cooling weeks turn packaged rooftops into all day assets. Filters that tolerated shoulder season loads cake quickly, coil faces collect cottonwood and mower dust, and economizer screens that looked fine in spring suddenly admit debris that shows up as afternoon comfort tickets on sales floors. Facility teams across the Southeast often dispatch HVAC vendors before anyone documents filter differential, coil intake condition, or whether the drain pan stayed dry through sustained run hours. These steps are for property and engineering staff who need a repeatable rooftop pass without opening refrigerant circuits on the first visit. Pair the checks with Garrett Mechanical commercial HVAC service and preventive maintenance when visual checks point past filter swaps alone.
If symptoms could be mechanical, plumbing, or electrical, start with the facility symptom priority quiz so this rooftop pass lands on the correct owner. If people are in danger now, pause and follow your emergency plan first.
Start with filter banks and differential notes
Open filter access on each packaged unit and photograph the dirty side before you swap. Note frame size, MERV rating if labeled, and whether bypass gaps show daylight around the media. If your team tracks differential pressure, write the reading with date and outdoor temperature. A filter that looks gray after two weeks of peak cooling is a different story from one that stayed clean through a mild May.
Keep spare media on the roof or in the mechanical room for the sizes you actually run. Emergency swaps with the wrong thickness leave gaps that pull unfiltered air past the coil. Pair filter work with preventive maintenance when multiple rooftops share the same calendar week.
Check coil faces and economizer screens
Look at the entering air face of the evaporator coil with a flashlight. Cottonwood, seed fluff, and mower dust pack the fins and cut airflow before the compressor ever fails. Note whether the coil looks wet and clean versus matted and dry. Do not bend fins with tools on a first pass. Call commercial HVAC when dirt is packed deep or you see ice on the coil during cooling.
Economizer screens and outdoor air intakes collect the same debris. Screens that stay clogged pull the unit toward recirculation only and raise afternoon comfort tickets on sales floors. Clear what you can reach safely. Photograph anything that needs a lift or lockout before the next visit.
Confirm drain pans stay dry through long run hours
Peak cooling fills condensate pans for hours. Look for standing water, algae mats, or stains beside the unit that track onto the roof. Clear visible debris from the pan and outlet if your lockout policy allows. A pan that overflows only on the hottest afternoons often points to a partial clog, not a new roof leak.
Inside the building, check the nearest ceiling tile or soffit for new stains under the same unit. Condensate and roof drainage can look alike in photos. Wide shots that show the unit, the pan outlet, and the nearest roof drain help the next technician start in the right place.
When visual checks are not enough
Filter and coil passes fix many afternoon warm complaints. They do not fix refrigerant issues, failed compressors, or control problems. If comfort tickets continue after clean filters and a clear coil face, schedule measured diagnostics through commercial HVAC and emergency service when occupied space is already uncomfortable.
Write unit tag numbers, filter sizes, and what you changed. Short notes beat vague tickets. Return to the cooling quiz when the loudest complaint might be plumbing or electrical instead of the rooftop.
What to bring to the next service visit
Save dated photos of filters before and after, coil faces, economizer screens, and any pan overflow marks. List which units you opened and which still need spare media. Gate codes, roof access rules, and preferred vendor windows belong in the same note so the visit does not stall at the door.
Contact Garrett Mechanical with that packet when you want filter and coil work on a steady calendar before the next heat stretch. Maintenance before peak weeks costs less than stacked comfort tickets when every floor runs cooling together.