By Commercial Service Company · August 10, 2026
When a commercial rooftop unit (RTU) stops cooling in the middle of an Arkansas summer, your whole operation is on the clock. Dining rooms empty out, walk-in and display temperatures start to climb, and product moves toward the spoilage line fast. The good news is that a few no-cool problems come from simple causes you can check safely. The rest are electrical, refrigerant, or compressor issues that belong to a licensed technician. Here is a practical way to work through it before you lose a full day of business.
Start With the Thermostat and Basic Settings
It sounds obvious, but a surprising number of no-cool calls trace back to the thermostat. Before you assume the worst, confirm the basics with fresh eyes.
- Make sure the thermostat is set to COOL and the setpoint is actually below the current room temperature.
- Check that a programmed schedule or setback isn't holding the unit off during business hours.
- If it's a battery-powered stat, replace the batteries and see if the display comes back to life.
- Verify no one bumped the mode to FAN-only or OFF during a shift change.
If the thermostat calls for cooling and nothing happens, move on to the power supply.
Check for a Tripped Breaker or Blown Fuse
Rooftop units pull heavy current when they're fighting Arkansas heat, and that load can trip a breaker. Find the RTU's breaker in your electrical panel and see if it has tripped. You can safely reset a breaker one time. If it trips again immediately, stop. A breaker that keeps tripping is protecting you from a real electrical fault—repeatedly resetting it can damage the equipment or create a fire risk. That's a call to a technician, not a second reset.
Dirty Filters and Coils Choke Airflow
Airflow problems are one of the most common reasons an RTU runs but won't cool. In summer, filters clog faster than most owners expect, especially in kitchen and grocery environments with grease and dust in the air.
- Check and change filters at least monthly during cooling season—more often in a busy kitchen.
- Look at the outdoor condenser coil on the rooftop. Cottonwood, grass clippings, dust, and kitchen-exhaust grease coat those fins and trap heat.
A blocked coil forces the system to run against high pressure, so it works harder and cools less. Filter changes are fair game for your staff. Deep coil cleaning on the roof is best left to a service tech who can do it without bending fins or damaging the unit.
Low Refrigerant Is Not a DIY Fix
If the unit runs constantly but only pushes warm or lukewarm air—or you notice ice on the refrigerant lines or a hissing sound—you may be low on refrigerant. Here's the important part: an RTU doesn't "use up" refrigerant. If it's low, there is a leak somewhere in the system. Adding refrigerant without finding and repairing that leak just wastes money and puts more refrigerant into the air. Refrigerant work is regulated by the EPA and requires certified handling and equipment. Do not attempt to add refrigerant or open the system yourself—call a licensed technician to find the leak and charge it correctly.
Contactor, Capacitor, and Control Failures
Inside the unit, a contactor acts like a heavy-duty switch that lets high voltage reach the compressor and condenser fan when cooling is called for. Over years of summer cycling, its contacts pit and burn, or a run capacitor weakens, and the compressor or fan won't start. You might hear a hum with no fan movement, or the unit may click and do nothing. These are high-voltage components. Diagnosing and replacing a contactor, capacitor, or compressor is not a DIY job—leave it to a qualified technician with the right tools and training.
Arkansas Summer Load Pushes Equipment to the Edge
Central Arkansas summers regularly push into the mid- and upper-90s with heavy humidity, and that load exposes every weak point in an RTU. A unit that limps through spring will often quit during the first real heat wave, because it simply can't shed enough heat when the outdoor air is already hot. That's why the smartest move is preventive maintenance before summer sets in—coil cleaning, electrical checks, refrigerant verification, and airflow inspection—so small problems get caught while they're cheap and your equipment isn't failing during your busiest, hottest days.
If your commercial rooftop unit still isn't cooling after you've checked the thermostat, breaker, and filters, don't let your building keep heating up. Commercial Service Company has served central Arkansas businesses since 1976 across Conway, Little Rock, Benton, Bryant, Maumelle, Jacksonville, Searcy, Russellville, and beyond. Call us at 501-548-2374 and we'll get a technician on your roof.