When a commercial refrigerator or commercial freezer starts running warm, the compressor gets the blame — but most of the time the problem is air: a coil that cannot shed heat, a door that does not seal, or a fan that has stopped moving cold air across the box. This guide walks through the ten most common reasons a commercial refrigerator is not cooling, in the order worth checking them, what you can fix yourself and what needs a technician.
First: confirm it is actually warm
The number on the display is a sensor reading, usually of the air near the evaporator, not of the food. Before you call anyone, put a calibrated thermometer in a glass of water on the middle shelf, close the door and read it after an hour or two.
- Commercial refrigerator: food must be held at 41°F or below. A reading of 36–38°F is healthy; anything above 41°F needs action now.
- Commercial freezer: 0°F is the usual target. A freezer holding 10–15°F is failing even if the product still feels frozen.
- Check whether it is in a defrost cycle. Most commercial units defrost automatically, typically about every 6 hours. A commercial refrigerator defrosts by stopping the compressor and letting the evaporator coil warm up; a commercial freezer runs heaters on the evaporator coil to melt the frost. Either way the cabinet temperature rises for a short time and drops back once defrost ends, so a single high reading during defrost is normal — check again after the cycle has finished.
- Give a freshly loaded unit time. A unit loaded with warm or unfrozen product takes time to pull down. A new, empty commercial freezer can reach −7°F within about 20 minutes, but fully loaded with product that is not yet frozen it can take as long as 48 hours to get there — that is normal. Judge it by whether the temperature keeps falling, not by how fast.
- If the display and the thermometer disagree by more than a few degrees, suspect the sensor or controller (cause 8) before anything else.
Symptoms at a glance
| What you see | Most likely cause | Who fixes it |
|---|---|---|
| Temperature rises for a short time every few hours, then drops back | Normal automatic defrost cycle | No fix needed |
| Runs constantly, cabinet slowly warming, hot air at the grille | Dirty condenser coil or blocked ventilation | You |
| Warm near the door (refrigerator) or heavy frost inside and slowly rising temperature (freezer) | Worn or torn door gasket, door not closing | You (gasket replacement) |
| Compressor running but no air moving inside | Evaporator fan motor, door switch, or a fan frozen in ice (freezer) | You (defrost first) or a technician |
| Compressor clicks on and off, unit hot at the back or bottom | Condenser fan motor, dirty coil, or start components | Technician |
| Thick frost or a block of ice on the evaporator cover | Defrost fault, gasket leak or clogged drain | You (manual defrost), technician if it returns |
| Display normal but thermometer reads warm | Temperature probe or controller | You (setting) or replace the controller |
| Runs all day, never reaches temperature, oily spots on tubing | Refrigerant leak or compressor failure | Technician |
10 common reasons a commercial refrigerator or freezer is not cooling
Most of these causes apply to both. Where a commercial refrigerator and a commercial freezer behave differently, each gets its own note.
1. Dirty condenser coil
This is the single most common cause, and the cheapest to fix. The condenser coil is where the unit dumps the heat it pulls out of the cabinet. In a kitchen it collects dust, flour and grease, and once the fins are matted the compressor runs longer and longer and still cannot hold temperature. On a bottom-mount reach-in such as the Polarman PLM series, the coil sits behind the front grille at floor level, right where kitchen grease settles.
Fix (refrigerator and freezer): unplug the unit, remove the grille and brush or vacuum along the fins (never across them). In a busy kitchen, clean the condenser coil monthly; in a cleaner front-of-house space, at least every three months.
2. Blocked airflow around the unit
A commercial refrigerator or freezer needs room to breathe. Boxes stacked against the front grille, a cabinet pushed tight against the wall, or a unit placed next to a fryer or oven all make the condensing unit work in hot, stale air. Undercounter units with a rear-mounted compressor are the most sensitive: pushing one flat against a wall is the most common reason an undercounter unit runs warm.
Fix (refrigerator and freezer): clear the grille, give the unit the clearance its manual specifies, and keep it away from cooking equipment where you can.
3. Worn door gasket or a door that does not close
Every gap in the gasket lets warm, humid kitchen air into the cabinet. Check by closing the door on a strip of paper at several points around the frame: if it slides out with no drag, the gasket is not sealing there.
Commercial refrigerator: the top shelf near the door runs warm, condensation forms along the door edge, and the compressor never rests.
Commercial freezer: the leaking air turns to frost — heavy frost builds up inside the cabinet, around the door frame and on the evaporator, and the temperature creeps up slowly over days.
Fix (refrigerator and freezer): clean the gasket with warm soapy water (grease makes it stiff and stops it seating), check the door hinges and that the cabinet is level so the door swings shut, and replace a gasket that is torn or flattened. Gaskets are model-specific — have the model number ready when ordering. On a freezer, defrost the built-up ice afterwards (cause 7).
4. Overloading and blocked interior airflow
A reach-in cools by moving air across the shelves. Cases stacked against the back wall or the evaporator fan cover, sheet pans covering whole shelves, or a large load of warm product all at once will leave parts of the cabinet warm while the display looks fine.
Fix (refrigerator and freezer): leave space at the back and between products and keep the fan cover clear. Cool hot food before it goes into a commercial refrigerator — it is not a blast chiller — and expect a commercial freezer to take time to pull a big delivery down to temperature (see the pull-down note above).
5. Evaporator fan not running
If the compressor is running but you feel no air moving inside the cabinet, the evaporator fan has stopped. Many units switch the fan off when the door opens, so first check that the door switch is not stuck.
Commercial refrigerator: a fan that hums but does not turn, or squeals, is failing.
Commercial freezer: before blaming the motor, look for ice. A fan blade frozen into frost on the evaporator cannot turn even though the motor is fine — defrost the unit first (cause 7) and check again.
Fix: free the door switch, clear any ice, and replace the fan motor if it is still seized. For Polarman units, replacement evaporator fan motors for upright units and for undercounters are stocked.
6. Condenser fan not running
The condenser fan pulls air across the condenser coil. When it stops, the compressor overheats and shuts itself off on its thermal overload, restarts when it cools, and shuts off again — you hear it clicking and the cabinet drifts warm. The cabinet base or back will feel noticeably hot.
Fix (refrigerator and freezer): check the fan blade is not obstructed, then replace the motor. Polarman condenser fan motors for upright units and for undercounters are stocked.
7. Iced-up evaporator or a defrost problem
Every time the door opens, warm, humid air comes in and its moisture freezes onto the evaporator coil. Automatic defrost clears it, typically about every 6 hours. That schedule is built for normal use, and every kitchen uses its units differently: when the doors are opened constantly during service — or held open for long stretches, like a cook leaning back against the door while working the line — more moisture comes in than defrost can clear. Frost builds up on the coil, the evaporator fan can no longer push cold air through it, and the cabinet warms up behind a wall of ice. A clogged drain or a failed defrost control ends the same way.
Commercial refrigerator: defrosts by stopping the compressor and letting the coil warm up — there is no defrost heater. For heavy or very heavy ice, switch it off, move the product, prop the door open and let the ice melt completely.
Commercial freezer: defrosts with heaters on the evaporator coil. For heavy frost, press and hold the manual defrost key on the controller to start the heaters; one manual cycle usually runs up to about 30 minutes, and a badly iced coil may need it repeated several times. If the ice is very thick, switch the unit off, move the product and let it melt completely.
Then (refrigerator and freezer): clear the drain line with warm water, keep doors closed between pulls and check the door gasket (cause 3). If heavy ice comes back within days under normal use, have a technician check the defrost system.
8. Wrong setting, failed probe or controller
Before anything else, check the set point — controllers get bumped during cleaning. On Polarman controllers, press and hold SET to enter the set temperature, then use the up and down keys to adjust it; other brands work in a similar way, so check the manual. If the setting is right but the cabinet temperature does not match the display, the temperature probe or the controller itself may have failed.
Commercial refrigerator: set it to the middle of the range, 36–38°F.
Commercial freezer: set it to around 0°F.
Fix: replace a failed controller with the correct one for the model; Polarman refrigerator controllers and freezer controllers are stocked.
9. Power supply problems
A commercial refrigerator or freezer is a continuous load, and its compressor draws a surge of current every time it starts. Extension cords, circuits shared with other equipment and long, undersized runs drop the voltage the compressor sees, so it struggles to start, overheats and trips. A breaker that trips repeatedly is a symptom, not the fault.
Fix (refrigerator and freezer): plug straight into a dedicated circuit with enough current capacity to spare — take the exact amps and breaker size from the unit's spec sheet, not from a rule of thumb. This is also one of the reasons commercial refrigeration is not recommended for home use: household circuits are usually shared and sized for smaller appliances. If a breaker keeps tripping on a dedicated circuit, call a technician.
Commercial freezer: a freezer draws noticeably more current than a refrigerator of the same size, so check the spec sheet before swapping one onto an existing circuit. Most Polarman reach-ins run on 115V with a standard 5-15P plug, but the three-door PLM-81FDVS reach-in freezer needs a 220V L14-20P receptacle.
10. Refrigerant leak or compressor failure
If the coils are clean, the fans run, the doors seal and the unit still runs all day without reaching temperature, the sealed system is the likely cause: a refrigerant leak, a failed compressor or its start components. Signs include oily residue on the tubing, frost only on part of the evaporator, or a compressor that hums but will not start.
Fix (refrigerator and freezer): this is technician work. Many current units, including Polarman reach-ins and undercounters, use R290, a hydrocarbon refrigerant that is efficient and low in global warming potential but flammable, so repairs to the sealed system must be done by a technician trained to work with hydrocarbon refrigerants.
A maintenance routine that prevents most of these
| How often | What to do |
|---|---|
| Daily | Log the temperature with a thermometer, not only the display; check doors close fully |
| Weekly | Wipe the door gaskets; check for frost build-up and that the drain is clear |
| Monthly | Clean the condenser coil in a busy kitchen (quarterly in a clean space); check the condenser and evaporator fans run quietly |
| Yearly | Have a technician check the refrigeration system, electrical connections and defrost operation |
Repair or replace?
Fans, gaskets, controllers and a coil cleaning are inexpensive and almost always worth doing. The decision comes with a compressor or a refrigerant leak on an older unit: a common rule of thumb is to replace rather than repair when the unit is past about ten years old or the repair approaches half the cost of a new commercial refrigerator. A new unit also brings back the full warranty and today's more efficient refrigerants.
Polarman warranty and replacement parts
Polarman reach-in and undercounter refrigerators and freezers carry 1 year labor, 2 years parts and 5 years compressor parts. Replacement parts — fan motors, controllers and more — are stocked in our own warehouse. Have the model and serial number from the data plate ready, and browse refrigeration parts and accessories.
Commercial refrigerator not cooling: FAQ
Why is my commercial refrigerator running but not cooling?
Most often the condenser coil is dirty or the unit has no room to vent heat, so the compressor runs but cannot reject heat. Next check that the evaporator fan is moving air inside and that the door gaskets seal. If all of those are fine, a technician should check for a refrigerant leak or compressor fault.
How often should I clean the condenser coil on a commercial refrigerator?
Monthly in a busy kitchen with grease and flour in the air, and at least every three months in a cleaner front-of-house location. Unplug the unit and brush or vacuum along the fins.
Why is my commercial freezer building up ice?
Ice comes from warm, humid air getting in — doors opened constantly or held open during service, or a worn gasket — or from a defrost system or drain that is not working. For heavy frost, press and hold the manual defrost key to run the heaters, up to about 30 minutes per cycle, and repeat if needed; if the ice is very thick, switch the unit off and let it melt completely.
Can I fix a commercial refrigerator myself?
Cleaning coils, clearing airflow, replacing door gaskets, fan motors and controllers are within reach for most operators. Anything in the sealed refrigeration system — refrigerant, compressor, start components — needs a qualified technician, especially on units using flammable R290 refrigerant.
Keep reading: Commercial refrigerator temperature guide · How to choose a commercial reach-in refrigerator or freezer · Commercial undercounter refrigerator buying guide
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