If your commercial refrigerator isn’t holding temperature, the cause is almost always one of two things: something in the sealed refrigeration system (compressor, refrigerant charge, metering device), or something outside it (door gaskets, fans, thermostat, condenser coils). The distinction matters because one category you can quickly check yourself; the other requires a licensed tech with recovery equipment.
Here’s how to think through it.
Start with the obvious checks
Before assuming the compressor is dying, check the things you can see and hear. These turn out to be the culprit on a fair number of calls.
Dirty condenser coils. On most reach-ins, the condenser is behind a louvered panel at the bottom or on top. If it’s caked with grease and dust, the unit can’t reject heat and will run warm. Pull the panel and take a look.
Door gaskets. A torn or deformed gasket leaks warm air constantly. Close the door on a dollar bill, then pull it out. If it slides out without resistance, the gasket isn’t sealing. On prep tables, lids and drawer seals fail the same way.
Evaporator fan not running. Open the unit and listen. If you don’t hear the evaporator fan moving air across the interior coils, refrigerant can’t transfer cold into the cabinet even if the compressor is working fine.
Thermostat or temperature controller. If the unit isn’t calling for cooling or is cutting out early, the box won’t hold temp.
Blocked airflow inside the cabinet. Overstacked shelves or product pushed against the evaporator coil will starve air circulation. It sounds basic, but it comes up.
When it’s the sealed system
If everything above checks out and the unit is still running warm, you’re likely looking at a sealed-system issue. These require a certified refrigeration tech, no exceptions. Handling refrigerant without EPA Section 608 certification is illegal, and misdiagnosis here gets expensive fast.
Signs that point to the sealed system:
Compressor runs but box won’t cool. If you can hear and feel the compressor running, the condenser is clean, but the evaporator coils inside aren’t getting cold, suspect low refrigerant or a failed metering device (TXV or cap tube).
Compressor won’t start or trips repeatedly. Could be a bad start relay, capacitor, or a compressor that’s failing mechanically. A tech will check amp draw and electrical components before condemning the compressor.
Ice buildup on the evaporator (too much). Some frost is normal. A solid block of ice means the defrost system has failed, or there’s an airflow restriction that caused the coil to freeze over. A tech will defrost it manually and test the defrost heater, timer, and termination thermostat.
Refrigerant leak. If the system is low on refrigerant, a tech won’t just top it off. They’ll find and fix the leak first, then recharge to the manufacturer’s spec. Adding refrigerant to a leaking system is a short-term patch that wastes money.
How a tech diagnoses this
A good technician will come in with manifold gauges and check system pressures against the manufacturer’s spec for the refrigerant type. Most commercial reach-ins built in the last decade or so run R-404A or R-448A (newer units may use R-449A or similar lower-GWP blends). Older units may still have R-22. High head pressure usually points to a condenser problem or refrigerant overcharge. Low suction pressure often means low charge or a restriction. Normal pressures but poor cooling shifts focus to airflow and defrost.
They’ll also check superheat and subcooling, which tells them whether the metering device is working correctly and whether the charge is right. You can’t reliably diagnose the system from pressures alone without those temperature measurements.
What you can check yourself
- Is the unit plugged in, and has the circuit breaker tripped? (Not as rare as you’d think.)
- Is the temperature controller set point where it should be?
- Is there product or shelving blocking airflow inside the cabinet?
- Does the door seal? (The dollar-bill test above tells you quickly.)
- Is the condenser panel visibly clogged with dust and grease?
Spotting those problems is the limit of what’s safe to do without training. Cleaning coils on a commercial unit, swapping a gasket, replacing a fan motor, touching anything electrical or refrigerant-related: those are tech jobs. Doing them wrong on a commercial unit usually costs more to put right than a service call would have.
When to call us
Call when the quick checks come up clean and the unit still isn’t holding temperature. Also call when you see heavy ice buildup on the evaporator, hear the compressor struggling, or the unit is holding food that needs to stay at 41°F or below per California food safety code. A failed unit during service means spoiled product and a potential health inspection problem.
Bay Area Refrigeration Service handles commercial refrigeration repair across the Bay Area, including walk-ins, reach-ins, ice machines, and prep tables. Call us or book at bayarearefrigerationservice.com. We’ll get you on the schedule fast, often same or next day when we can.