Most under-counter coolers stop cooling for one of three reasons: the condenser is dirty, the evaporator fan has failed, or the refrigerant charge is low. A tech can usually tell which one within a few minutes of opening the unit. Here’s how to work through it.
The Most Common Cause: A Dirty or Blocked Condenser
This is where I’d start nine times out of ten. Under-counter units live in the worst spot in a commercial kitchen, right at floor level, pulling air through a grille that collects grease, dust, and debris around the clock. When the condenser coil gets coated, it can’t shed heat. The compressor works harder, the high-pressure side climbs, and eventually the unit either trips on a safety or just runs warm indefinitely.
Access location varies by brand and model. True units often pull from the front grille; Beverage-Air typically from a rear panel. A coil packed solid with grease and dust is a common find. Cleaning it properly requires the right coil cleaner and technique. Bent fins from an aggressive cleaning approach reduce airflow and can make things worse, not better.
Evaporator Fan Motor
If the condenser is clean and the unit still isn’t cooling, check airflow inside the cabinet. The evaporator fan pulls air over the coil and circulates it. If that motor burns out or the blade gets iced over and stalls, you’ll get a cabinet that feels warm even though the compressor is running.
One thing to know: most commercial under-counter units (True, Continental, Beverage-Air) have a door switch that stops the evaporator fan when the door is open. You can’t just open the door and listen for it. A tech bypasses that switch to confirm the fan is actually running.
Ice buildup around the evaporator fan is a different symptom. It usually points to a defrost problem or a door gasket that’s letting humid air in. If the coil is encased in ice, turn the unit off and leave the door cracked. A heavily iced evaporator can take many hours to defrost fully. Once it’s clear, watch whether it ices over again within a few days. If it does, there’s an underlying issue that needs attention.
Low Refrigerant
Refrigerant doesn’t just disappear. If a unit is low, there’s a leak somewhere, and adding refrigerant without fixing the leak is a temporary fix at best.
Signs of a refrigerant issue: the compressor runs continuously but the cabinet never gets down to temp; the evaporator coil is only partially frosted; or you see oily residue near the fittings or along the copper lines (refrigerant oil follows wherever refrigerant escapes). A tech will use an electronic leak detector or UV dye to find the source before recharging.
This one is not DIY. EPA Section 608 requires certification to purchase and handle refrigerants commercially. Beyond the legal side, a proper repair involves finding and fixing the leak, pulling a vacuum, and recharging to spec. That requires manifold gauges and recovery equipment most operators don’t have.
Compressor and Electrical Issues
If the condenser is clean, the fan is running, and refrigerant charge is good, the compressor itself may be the problem. A compressor that starts but trips the overload, hums but doesn’t run, or won’t start at all needs a technician. Start relay and capacitor failures are common on older units and are relatively inexpensive parts to replace. A failed compressor on a smaller under-counter unit sometimes makes a replacement conversation worth having, depending on the age.
Also worth a look: the thermostat or controller. A failed controller, or a mechanical thermostat with a stuck-open contact, means the compressor never gets the signal to run. On units with a digital controller (common on newer True models), a fault code on the display can point toward the right subsystem. Check the manufacturer’s documentation for that specific model before drawing conclusions.
What You Can Check Yourself
A few things are safe to look at before calling:
- Confirm the unit has power and the breaker hasn’t tripped.
- Check the temperature setting. It happens.
- Look for obvious debris blocking the condenser grille.
- Make sure the unit has adequate clearance for airflow on all sides.
- Inspect door gaskets for tears or gaps.
- Look for heavy ice buildup around the evaporator. If you find it, turn the unit off and let it defrost with the door cracked open.
Anything beyond those visual checks, including condenser cleaning, fan motor testing, refrigerant work, and compressor wiring, is a job for someone with the right tools and training.
Time to Call
If you’ve confirmed power, checked settings and clearance, and the unit still isn’t cooling, call a tech. Same goes for any refrigerant issue, compressor noise, or fault code you can’t resolve from the manufacturer’s documentation. The longer a commercial unit runs warm, the more product you risk and the harder the compressor works.
Bay Area Refrigeration Service handles commercial refrigeration repair across the Bay Area, including under-counter units, reach-ins, prep tables, and walk-ins. Call us or book at bayarearefrigerationservice.com and we’ll get you on the schedule fast, often same or next day when we can.