By Commercial Service Company · November 4, 2026
If you run a restaurant, grocery store, or any building cooled by a rooftop package unit, there's a good chance that unit has an economizer built into it. Most owners never think about this part until their energy bills jump or their dining room feels swampy on a mild day. Here's what it does and why it fails.
What an Economizer Actually Does
An economizer is a set of dampers and controls mounted on the rooftop unit that lets it pull in outside air instead of running the compressor to cool recirculated indoor air. On a mild day - say 55 to 65 degrees outside - the unit can open the outside air damper, shut down or reduce mechanical cooling, and use that free outside air to cool the building. That's where the nickname "free cooling" comes from.
When it's working right, this cuts how often the compressor has to run, which means less wear on expensive components and lower energy use during shoulder seasons - spring and fall in central Arkansas, when it's not too hot or too humid outside.
How a Stuck Damper Costs You Money
The economizer damper is a mechanical part with a motor, linkage, and sensors. Like any mechanical part, it can stick, bind, or fail - and when it does, it usually fails in one of two costly directions.
- Stuck shut: The unit never gets its free cooling. It leans on the compressor year-round, even on mild days when it didn't need to. You pay full cooling costs on days you shouldn't have to.
- Stuck open: This is the one that catches owners off guard. If the damper sits open or doesn't close all the way, the unit keeps pulling in outside air even during hot, humid Arkansas summer days. That means the system is fighting to cool and dehumidify a steady stream of hot, moist outside air on top of its normal load. Compressors run longer, humidity creeps up inside, and in food service or grocery settings that extra moisture can affect product, comfort, and even create condensation issues.
Either failure mode tends to be gradual. The building doesn't suddenly feel wrong - bills just creep up, or the air inside feels a little heavier than it should. Most owners don't catch it until a technician points it out or the energy bill gets hard to ignore.
Why Dampers Stick
Economizer dampers live outdoors on a rooftop, exposed to Arkansas heat, cold, rain, and pollen. Common culprits include:
- Linkage arms that corrode or lose their connection to the actuator motor
- Actuator motors that wear out or lose calibration
- Dirt, debris, insulation, or grease buildup (common near kitchen exhaust) jamming the damper blades
- Failed or drifting outside air sensors that tell the unit the wrong temperature or humidity, so it makes the wrong call on when to open or close
- Control board or wiring issues that stop the damper from getting a signal at all
None of this is usually visible from the ground. The only way to know your economizer is doing its job is to have someone check it directly on the roof.
What a Tech Checks on a Maintenance Visit
When our technicians service a rooftop unit, the economizer gets a specific set of checks:
- Cycle the damper through its full range and confirm it opens and closes smoothly, without binding
- Inspect the linkage and actuator for wear, corrosion, or disconnection
- Check that the damper blades seal properly when closed - gaps here let in unwanted outside air even when the system thinks it's shut
- Test the outside air sensor readings against actual conditions to catch drift
- Clean out dirt, debris, or grease buildup around the damper and linkage
- Confirm the control sequence is actually switching between economizer and mechanical cooling the way it's supposed to
Any issues involving the unit's electrical controls, refrigerant circuit, or compressor should always be handled by a licensed technician - these components carry real safety risks and are not something to troubleshoot on your own.
Why This Matters for Central Arkansas Buildings
Our swing seasons - spring and fall - are exactly when an economizer should be earning its keep, and our humid summers are exactly when a stuck-open damper does the most damage. A rooftop unit that's never had its economizer checked is a coin flip: it might be quietly saving you money, or it might be quietly working against you.
If your rooftop unit is a few years old and nobody's specifically checked the economizer, it's worth having a look before the next big swing in weather. Give Commercial Service Company a call at 501-548-2374 and we'll get a technician out to your Conway, Little Rock, Benton, Bryant, Maumelle, Jacksonville, Searcy, or Russellville area location to take a look.