When a building isn't cooling properly during a heat wave, facilities teams often ask the same questions: Why is my system running constantly? Why are some areas warmer than others? Is my equipment at risk of failure?
The answer often comes down to what happens when commercial HVAC systems face extended periods of extreme heat. Higher cooling demand, longer system run times and less overnight recovery can expose maintenance and performance issues that may not be noticeable during cooler months.
Below, our experts answer six of the questions we hear most often when summer is in full force.
One important note: No two facilities are exactly alike. Equipment type and age, facility use, occupancy, size and layout, control sequences, operating schedules, maintenance history and indoor requirements all shape what is happening in your building. Consider this a starting point rather than a diagnosis.
Short answer:
Uneven cooling, where some zones stay comfortable while others run warm, usually points to an airflow or air distribution issue rather than a system that is simply “too small” or “can’t keep up.”
Common contributors include:
Dirty coils or clogged filters restricting airflow.
Blocked or leaking ductwork.
Failing blower components.
Dampers and controls that are out of adjustment.
Summer heat makes the imbalance more noticeable because the system is already running near capacity, so any zone that is already struggling falls behind faster.
What your facilities team can do:
Track where and when hot spots occur.
Document comfort complaints by area.
Review building automation system (BAS) trends and alarms for recurring patterns.
Confirm thermostat settings and schedules match how spaces are being used.
Note any recent changes to occupancy or building operations.
“The best thing a facilities team can do is pay attention to the patterns," said Michael King, Service Tech III, HVAC at TDIndustries. "Track where and when hot spots show up, note comfort complaints by area, watch for alerts or trends in your building automation system, and make sure thermostat settings and schedules actually match how each space is used. That information helps us pinpoint the problem a lot faster."
When to call a qualified commercial HVAC professional:
Temperature differences between zones continue to worsen.
Occupant comfort issues become frequent.
Critical environments cannot maintain required conditions.
Airflow restrictions, control issues or equipment performance concerns are suspected.
The issue persists despite schedule and setpoint verification.
In mission critical settings like healthcare facilities, where temperatures and airflow must stay within a specific range, ongoing comfort issues should be looked at by a qualified commercial HVAC professional right away.
Short answer:
During a heat wave, longer HVAC run times are usually normal. Systems may need to operate nearly continuously to maintain the set point, depending on the equipment and building requirements.
What deserves a closer look is extended run time paired with any of the following:
A building that no longer reaches its target temperature.
Slow overnight recovery.
An increase in energy use that is greater than expected for the weather conditions.
Because HVAC systems are typically some of the largest energy consumers in a commercial facility, a struggling system often appears on the utility bill before comfort issues become noticeable. Common contributors include dirty coils and filters, low refrigerant levels or leaks, aging or improperly sized equipment, and control settings that keep systems running longer than necessary.
What your facilities team can do:
Your team can safely keep an eye on a few things:
Check the building automation system (BAS) for unusual operating patterns, such as equipment running after hours, frequent alarms, excessive runtime or spaces consistently missing temperature setpoints.
Compare current energy use to previous months and seasons.
Verify schedules and temperature settings are correct.
Document changes in occupancy, operating hours or building usage.
Track when performance issues occur and whether they coincide with spikes in energy consumption.
When to call a qualified commercial HVAC professional:
The building can no longer maintain target temperatures.
Overnight recovery becomes unusually slow.
Energy costs rise significantly beyond what weather conditions would suggest.
Equipment appears to be operating continuously without achieving desired results.
Refrigerant, compressor, controls or equipment sizing issues are suspected.
TDIndustries’ HVAC planned maintenance programs are built to keep systems running efficiently and help facilities avoid emergency repairs and premature part replacement.
Short answer:
A space can feel sticky even when the thermostat reads at a reasonable temperature, and that’s a signal worth investigating. Cooling and dehumidification are related but separate jobs. When a system is oversized, short-cycling or moving air too quickly across the coil, it can lower the temperature without removing enough moisture. Elevated humidity can affect occupant comfort, indoor air quality and building conditions.
During prolonged heat and high outdoor moisture, systems work harder to manage that moisture load, so borderline humidity problems become obvious quickly.
As Daniel Gullion, Service Manager at TDIndustries, explains, "People assume a cooler space is a drier space, but those are two different jobs. If a system isn't sized or running right, you can hit your temperature set point and still be fighting moisture all day."
What your facilities team can do:
Monitor indoor humidity levels and temperature trends.
Watch for condensation on windows, ductwork or other surfaces.
Note musty odors, damp areas or occupant complaints.
Confirm that ventilation schedules and control settings have not changed.
Document when and where humidity concerns occur.
When to call a qualified commercial HVAC professional:
Humidity remains elevated despite normal cooling.
Condensation or moisture-related issues persist.
Indoor air quality concerns develop.
Occupants continue to report comfort concerns.
Equipment sizing, controls, airflow or dehumidification strategies need evaluation.
A qualified commercial HVAC professional can diagnose airflow, control and equipment issues; inspect components such as sensors, dampers, fans and motors; evaluate drainage and dehumidification performance; and recommend humidity-control strategies appropriate for your facility.
Humidity targets are specific to each facility, especially in healthcare buildings, schools and warehouses storing sensitive inventory, so they depend on manufacturer guidance and your building's requirements.
Short answer:
Most commercial HVAC failures develop gradually and give off signals well before a full breakdown. Identifying those signs early can help reduce downtime and avoid emergency repairs.
What your facilities team can do:
Watch for:
New or unusual noises such as grinding, banging or squealing.
A building that stops recovering overnight.
Comfort complaints that start earlier each day.
Short-cycling (the system turning on and off rapidly).
Unusual odors, visible leaks or moisture.
Energy use that climbs ahead of any change in comfort.
When to call a qualified commercial HVAC professional:
Warning signs persist or become more frequent.
Cooling performance declines.
Equipment begins short-cycling regularly.
Moisture issues or leaks are discovered.
Reliability concerns begin affecting operations.
Contact a qualified commercial HVAC professional immediately if you observe:
Burning odors.
Smoke.
Sparks.
Water intrusion near electrical components.
Repeated breaker trips.
Extended heat waves force HVAC systems to run longer with little idle time, increasing the likelihood that worn components will fail if existing issues are left unaddressed. While a single warning sign may not indicate a serious issue, persistent or worsening symptoms should be evaluated before they lead to equipment failure or unplanned downtime.
Short answer:
A few safe, basic checks can help your team gather useful information and sometimes resolve minor issues. These observations give technicians useful context, helping them identify patterns, troubleshoot more efficiently and reduce downtime.
What your facilities team can do:
Before calling, gather the following information:
Review BAS alerts and recent system trends.
Document comfort complaints and the specific areas affected.
Confirm accessible thermostat settings, set points and schedules.
Note any unusual sounds, odors or operating patterns.
Review recent maintenance records for context.
“Even providing simple details about where issues are occurring and when they started can help technicians identify patterns and focus their investigation,” King said.
When to call a qualified commercial HVAC professional:
Basic observations do not identify the source of the problem.
Performance continues to decline.
The issue affects business operations or occupant comfort.
Repairs, diagnostics or system adjustments are needed.
Potential safety concerns are present.
The line between observation and repair is important. Opening panels, resetting or bypassing equipment, handling refrigerant or working on electrical components should be completed by qualified commercial HVAC professionals.
Short answer:
We hear this one a lot, and our answer is: Don't wait. Summer places the greatest demand on commercial HVAC equipment, making it one of the most important times to stay current on maintenance.
Think of it like a car towing a heavy load uphill on a hot day. Conditions that might not cause problems under normal circumstances can quickly lead to a breakdown when equipment is working at its limits.
What your facilities team can do:
Keep scheduled maintenance appointments.
Monitor equipment performance and comfort trends.
Report new noises, vibrations or performance changes promptly.
Document recurring issues.
Maintain accurate maintenance records.
Inspect condenser coils for dirt, debris and seasonal buildup, especially at facilities that operate continuously, such as hospitals and data centers, or have significant tree coverage, and consider a mid-summer cleaning.
"One of the most important things on-site facilities teams can monitor during the summer is condenser coil cleanliness," said King. "Dirty coils can increase operating pressures and temperatures, reduce efficiency and contribute to equipment failures."
When to call a qualified commercial HVAC professional:
Cooling performance begins to decline.
Components show signs of wear.
Equipment is operating differently than normal.
Reliability becomes a concern.
You need guidance on maintenance frequency or scope.
Common components that may fail during periods of peak demand include:
Worn belts.
Aging capacitors.
Motors operating under excessive load.
Staying current on maintenance helps identify developing issues before they become emergencies and gives technicians a better understanding of equipment history and operating conditions.
The common thread across these questions is proactive attention. Monitoring system performance, documenting trends and staying current on maintenance can help prevent minor concerns from becoming major disruptions.
If your team is navigating summer HVAC concerns, working through a troubleshooting question, evaluating system performance or planning proactive maintenance, our experts are here to help.
Contact a TDIndustries expert to talk through what you are seeing and find the right path forward for your facility.