When the school year ends, the HVAC systems that kept classrooms comfortable for nine months face a sudden shift in demand. A seasonal strategy for school situations isn't just about flipping a switch from "cool" to "off." It's about protecting expensive equipment, preventing emergency repairs during the hottest months, and ensuring the building is ready for the next academic year. Getting this wrong can lead to mold outbreaks, compressor failures, and a frantic call to a senior tech in August when the superintendent is touring the building.

Why a Dedicated Seasonal Strategy for Schools Differs from Commercial Buildings

Schools present a unique set of challenges that standard commercial buildings don't. The occupancy pattern—intense use for nine months, followed by three months of minimal activity—creates specific stress points. Additionally, the building envelope in many schools is older, with single-pane windows and insufficient insulation. A seasonal strategy must account for these factors to prevent costly damage.

Extended Idle Periods and Equipment Degradation

HVAC equipment that sits idle for weeks or months can suffer from seal drying, belt cracking, and bearing corrosion. Unlike a retail space that sees daily traffic, a school's rooftop units (RTUs) may not run at all for 60 to 90 days. Without a proper shutdown procedure, the first startup in August can cause a refrigerant leak from dried-out gaskets or a seized compressor from stagnant oil.

Budget and Procurement Cycles

School districts operate on fiscal years that often end June 30. This means repair budgets are tightest in the summer, exactly when the system is most vulnerable. A seasonal strategy that includes proactive maintenance in late spring can catch issues before the budget freeze, allowing for parts procurement during the school year's final quarter.

Indoor Air Quality (IAQ) Risks

Empty classrooms with stagnant air are breeding grounds for mold and bacteria. The EPA has documented that poor IAQ in schools can lead to health complaints from staff working during the summer and students returning in the fall. A seasonal shutdown must include a plan for maintaining ventilation and humidity control, even when the building is unoccupied.

The Pre-Shutdown Inspection: What to Check Before Summer Break

The seasonal strategy begins two to three weeks before the last day of school. This is the window to identify issues that need immediate attention versus those that can wait for the summer maintenance schedule. A thorough inspection at this stage prevents the "panic call" in July when a critical unit fails.

Refrigerant Circuit Integrity

Check all accessible refrigerant lines, especially on RTUs and split systems. Look for oil stains, which indicate a slow leak. Use an electronic leak detector on all service valves and Schrader cores. A slow leak that goes unnoticed over the summer can result in a completely empty system by August, requiring a full evacuation and recharge. Document the subcooling and superheat readings for each circuit as a baseline for the fall startup.

Condensate Drain and Pan Condition

The number one cause of summer mold in schools is a clogged condensate drain. When the system shuts down, standing water in the pan becomes a breeding ground. Clear the drain line with compressed air or a wet/dry vacuum. Pour a cup of distilled water with a few ounces of bleach or a commercial algaecide into the drain pan to kill existing growth. Inspect the pan for rust or cracks—if it's compromised, replace it during the summer, not when it leaks through the ceiling in September.

Electrical Connections and Contactors

Cycling equipment off for months can cause contactors to weld shut or become pitted. Inspect all contactors and relays. Check capacitor microfarad readings against the nameplate rating. A capacitor that is 10% or more out of spec should be replaced now, not when the compressor fails to start in the fall. Torque all electrical connections to manufacturer specifications—loose connections are a fire risk in idle equipment.

Step-by-Step Summer Shutdown Procedure

This is the core of the seasonal strategy. Following a standardized shutdown procedure ensures no step is missed, regardless of which technician performs the work. Document each step on a checklist and file it with the equipment log.

  1. Set the thermostat to "Off" and "Heat" or "Cool" to "Off"—do not just raise the setpoint. The system must be fully disabled to prevent short cycling during unoccupied periods.
  2. Disconnect power at the disconnect switch—do not rely on the breaker alone. Lock out/tag out (LOTO) the equipment per OSHA standards.
  3. Clean or replace all filters—a dirty filter left in place over the summer will grow mold and restrict airflow on startup.
  4. Inspect and clean evaporator and condenser coils—use a non-acid coil cleaner. Rinse thoroughly. Coils left dirty will corrode faster in humid conditions.
  5. Lubricate all fan and motor bearings—use the correct grease for the application. Over-greasing can cause bearing failure.
  6. Check and tighten all belt drives—replace belts that show signs of cracking or glazing. Leave belts slightly looser than operating tension to relieve stress during idle time.
  7. Close the outdoor air damper—this prevents humid outside air from entering the building and reduces the load on any dehumidification systems that may run.
  8. Secure all access panels and covers—use tamper-resistant screws if possible. Rodents and birds can cause extensive damage in an open unit.
  9. Document the shutdown—take photos of the unit, the thermostat setting, and the disconnect status. Note any abnormal findings in the maintenance log.

Managing Humidity and Ventilation During the Summer

Even with the system shut down, humidity control is critical. Many schools have dedicated dehumidification units or building automation systems (BAS) that can run exhaust fans on a schedule. A seasonal strategy must address how to keep relative humidity below 60% to prevent mold growth.

Using Building Automation Systems (BAS) for Summer Mode

If the school has a BAS, program a "summer unoccupied" schedule. This should run the supply fan for 10 minutes every two hours to circulate air and prevent stagnation. If the system includes a dehumidification cycle, enable it to run when the indoor humidity exceeds 55%. Ensure the BAS is set to override the thermostat's "off" command for the fan only—do not let the compressor cycle on unless absolutely necessary.

Portable Dehumidifiers for Problem Areas

In schools without a BAS, place portable dehumidifiers in known problem zones: basements, locker rooms, and rooms with exterior walls. Set them to drain continuously into a floor drain or use a condensate pump. Check and empty the reservoirs weekly—a full reservoir that shuts off the unit defeats the purpose. This is a task that can be assigned to summer custodial staff with proper training.

Monitoring and Alerts

Install wireless temperature and humidity sensors in at least three locations per building: one on the ground floor, one on the top floor, and one in the basement or crawl space. Many affordable systems send alerts to a smartphone if humidity exceeds 65% or temperature drops below 50°F. This allows a technician to respond before mold becomes visible.

Common Mistakes Technicians Make During School Shutdowns

Even experienced technicians can make errors during the seasonal transition. These mistakes are common and can lead to expensive callbacks or equipment damage.

Leaving the Thermostat in "Cool" Mode with a High Setpoint

This is the most frequent error. A thermostat left in "Cool" mode with a setpoint of 80°F will still call for cooling if the building temperature rises above that. On a 95°F day, the system may cycle on and off, causing short cycling, compressor overheating, and unnecessary wear. Always set the system to "Off" at the thermostat and the disconnect.

Forgetting to Secure Outdoor Units

Condenser units on the ground are vulnerable to lawn equipment, vandals, and animals. After shutdown, install a lockable cover or chain-link enclosure. At a minimum, place a heavy-duty mesh screen over the coil to prevent debris accumulation. Many technicians skip this step, only to find a damaged coil in the fall from a weed whacker or a nest of mice.

Neglecting the Economizer

Economizer dampers that are left open or partially open will allow humid outdoor air to enter the building. This increases the load on any dehumidification equipment and can cause condensation on cold surfaces inside the building. Close and lock the economizer damper. If the damper actuator is motorized, disconnect it to prevent accidental opening during a power surge.

Failing to Document the Shutdown

Without documentation, there is no way to verify that the shutdown was performed correctly. A technician returning in the fall may assume the system is ready to start, leading to a startup failure. Always complete a written checklist and attach it to the unit or store it in the building's maintenance file. Digital photos of the thermostat setting and disconnect status provide irrefutable proof.

When to Call a Senior Technician or Inspector

Not every issue can be handled by a junior technician during a seasonal shutdown. Recognizing the limits of your training and experience is a sign of professionalism, not weakness. Call for backup in these situations.

Refrigerant Leaks That Require EPA Certification

If you find a refrigerant leak that requires repair, you must comply with EPA Section 608 regulations. Leaks in systems with 50 or more pounds of refrigerant must be repaired within 30 days if the leak rate exceeds the threshold. A senior technician or certified refrigerant handler should oversee the repair and documentation. Do not attempt to patch a leak without proper certification—it violates federal law and can result in fines.

Electrical Panel Issues or Arc Flash Hazards

If the disconnect switch or electrical panel shows signs of arcing, burning, or excessive heat, stop immediately. Arc flash hazards require specialized training and personal protective equipment (PPE). A senior technician or an electrical contractor should evaluate the panel. Do not attempt to replace a breaker or repair a bus bar without the proper qualifications.

Structural Damage or Water Intrusion

If you find water stains on the ceiling near an air handler, or if the condensate pan is rusted through, the issue may be more than a clogged drain. Water intrusion can indicate a roof leak, a failed drain pan, or a cracked coil. An inspector or a senior technician should assess the extent of the damage before any repairs are made. Improperly addressing water damage can lead to mold remediation costs that dwarf the original repair.

Building Automation System (BAS) Programming Errors

If the BAS is not responding to commands or is showing erratic behavior, do not attempt to reprogram it without training. A misprogrammed BAS can run the chiller on a 90°F day or leave the building unventilated for weeks. Call a senior technician who is certified on the specific BAS platform. Many manufacturers require specific credentials to access the programming interface.

Fall Startup Checklist: The Reverse of Shutdown

A seasonal strategy is not complete without a plan for the fall startup. The same discipline applied to shutdown must be applied to bringing the system back online. Rushing this step can cause equipment damage on the first day of school.

  • Restore power at the disconnect—verify voltage and phase balance before closing the disconnect.
  • Check all safety controls—test high-pressure switches, low-pressure switches, and freeze stats.
  • Inspect belts and bearings—replace any belts that show signs of cracking from sitting idle.
  • Open the outdoor air damper—verify it operates freely and seals properly when closed.
  • Start the system in fan-only mode—run the fan for 15 minutes to circulate air before engaging the compressor.
  • Check refrigerant pressures and temperatures—compare to the baseline readings taken during shutdown.
  • Verify airflow—measure static pressure and adjust fan speed if necessary.
  • Test the economizer operation—cycle it through its full range of motion.
  • Document the startup—record all readings and note any discrepancies from the shutdown baseline.

Practical Takeaway

A seasonal strategy for school situations is about preventing problems, not reacting to them. By following a standardized shutdown procedure, managing humidity during the idle period, and knowing when to call for help, you protect the equipment, the building, and the budget. Document every step, communicate with the facility manager, and treat the summer shutdown with the same rigor as a critical repair. The result is a school that is ready for students in the fall, with no emergency calls and no surprises.