By Commercial Service Company · September 26, 2026
When the rooftop unit at your restaurant, store, or office building starts acting up, it's usually not a mystery to a trained tech — it's a checklist. Commercial RTUs are built to be serviced in a set order, and skipping steps is how simple problems turn into expensive ones. Here's what a Commercial Service Company technician actually looks at, in the order we look at it, when we're called out to troubleshoot a rooftop unit in Conway, Little Rock, or anywhere else in central Arkansas.
1. Thermostat and Controls First
Before anyone climbs a ladder, we check the thermostat or building automation controller. Is it calling for heat or cooling? Is the schedule set correctly? Is the setpoint reasonable? A surprising number of "broken unit" calls turn out to be a thermostat with a dead battery, a wrong schedule, or a control setting that got bumped. This step costs nothing and rules out the easiest fix.
2. Power and Disconnects
Next we verify the unit is actually getting power — disconnect switches in the "on" position, breakers not tripped, and control transformers not blown. If a breaker keeps tripping, that's a sign of a deeper electrical issue and not something to keep resetting. Any electrical diagnosis or repair beyond visual inspection is handled by a licensed technician, never something a building owner should attempt.
3. Airflow — Filters, Coils, and Ductwork
Restricted airflow is one of the most common causes of rooftop unit problems, and it's also one of the most preventable. We check:
- Filter condition — dirty filters choke airflow and stress the blower motor
- Evaporator and condenser coil condition — dirt and debris reduce heat transfer
- Blower operation and belt condition, where applicable
- Ductwork and dampers for obstructions or closed positions
A unit starving for air will short cycle, freeze up, or fail to hit temperature no matter how much refrigerant is in the system.
4. Outdoor Condition of the Unit Itself
Up on the roof, we look at the physical condition of the cabinet: standing water, damaged panels, debris around the condenser, vegetation growth, and signs of pest intrusion. Rooftop units take a beating from Arkansas weather — sun, hail, ice, and wind — and physical damage or blockage around the unit is often visible before you ever get to electrical or refrigerant checks.
5. Compressor and Refrigerant System
Once the basics check out, we move to the sealed system — compressor operation, pressures, and refrigerant charge. This step requires EPA-certified equipment and training, and it's where DIY troubleshooting needs to stop. Low charge, a failing compressor, or a restriction in the refrigerant circuit all show up differently on gauges, and misreading them (or adding refrigerant to a system that's actually leaking) can turn a repairable issue into a compressor replacement. This part of the job is for a licensed technician only.
6. Gas Heat Components, If Equipped
For gas-fired rooftop units, we check burner operation, ignition, and venting. Gas work carries real safety risk — carbon monoxide exposure and fire hazard among them — so any inspection or repair of gas components must be done by a qualified technician, not a maintenance staffer or facility owner working alone.
7. Sequence of Operation and Cycle Testing
With the individual components checked, we run the unit through a full cycle — call for cooling or heat, watch the stages engage, confirm the unit satisfies the thermostat and shuts down properly. This is where intermittent problems, like a component that works fine for ten minutes and then fails, tend to show up.
Why the Order Matters
Jumping straight to "it probably needs refrigerant" or "it's probably the compressor" without checking filters, airflow, and controls first leads to paying for parts that were never the problem. A methodical check, starting with the cheapest and easiest things to rule out, saves building owners money and gets the unit back online faster.
When to Call a Tech Instead of Guessing
Basic checks like verifying the thermostat setting or looking at a filter are reasonable for building staff to do. Anything involving electrical components, refrigerant, gas, or the compressor should be left to a licensed technician — both for safety and because misdiagnosis at that level tends to get expensive.
If your rooftop unit isn't keeping up, is short cycling, or just isn't cooling or heating the way it should, don't guess at the cause. Commercial Service Company has served businesses across Conway, Little Rock, Benton, Bryant, Maumelle, Jacksonville, Searcy, and Russellville since 1976. Call us at 501-548-2374 and we'll get a technician out to run the checklist and get your equipment back to work.