Commercial Freezer Malfunction 1:

"Power is on, but control board does not display"

Possible Cause:

1. Phase loss or fuse blown
2. Power phase open or transformer shorted
3. Control board failure

Possible Solution:

1. Check wiring for breaks and replace fuse
2. Check transformer output voltage (12V)
3. Replace cold storage room control board

Commercial Freezer Malfunction 2:

"Control board displays, but compressor does not run"

Possible Cause:

1. Compressor relay tripped
2. Hi-Lo pressure safety switch shut down
3. Defective contactor or coil
4. Cold room temperature is lower than operation set-point
5. Internal thermal overload tripped
6. Compressor malfunction

Possible Solution:

1. Determine reason and take corrective action
2. Determine type and cause of shutdown and correct it before re-setting safety switch
3. Repair or replace
4. Reset operation temperature setpoint
5. Wait until compressor cools down for reset
6. Check compressor motor winding

Commercial Freezer Malfunction 3:

"High discharge pressure"

Possible Cause:

1. Dirty condenser coil
2. Fan not running
3. System overcharged with refrigerant

Possible Solution:

1. Clean commercial freezer condenser coil
2. Check fan motor and it's electrical circuit
3. Reclaim excess refrigerant

Commercial Freezer Malfunction 4:

"Low discharge pressure"

Possible Cause:

1. Insufficient refrigerant in system
2. Low suction pressure

Possible Solution:

1. Check for leaks; repair and add charge
2. See corrective steps for low suction pressure 

Commercial Freezer Malfunction 5:

"High suction pressure"

Possible Cause:

1. Excessive load
2. Expansion valve overfeeding

Possible Solution:

1. Reduce load
2. Regulate superheat

Commercial Freezer Malfunction 6:

"Low suction pressure"

Possible Cause:

1. Lack of refrigerant
2. Plugged suction filter
3. Evaporator dirty or iced
4. Fan not operating
5. Expansion valve underfeeding

Possible Solution:

1. Check for leaks, repair, and add charge
2. Replace suction filter
3. Clean and defrost
4. Check fan motor and circuit control
5. Regulate superheat

Commercial Freezer Malfunction 7:

"Large difference between actual cold storage room temperature and setpoint on control panel"

Possible Cause:

1. Incorrect room temperature
2. Sensor placement, wire too long
3.  Sensor contact open

Possible Solution:

1. Reposition sensing point of temperature sensor
2. Enlarge wire section
3. Reconnect sensor

Commercial Freezer Malfunction 8:

"Heavy frost builds up on evaporator fins"

Possible Cause:

1. Too much time between defrost cycles or incompleted defrosts

Possible Solution:

1. Manual defrost and adjust defrost cycle

Commercial Freezer Evaporators

Moisture from the air freezes onto the evaporator coils (the cooling coils in the freezer) and forms an insulating barrier to heat transfer. Airflow also decreases as the passages narrow due to ice buildup. Each evaporator has a defrost cycle to melt frost/ice that has built up on the evaporator coils. Water from the melted ice is drained from the freezer . . . ideally.

It’s not unusual, however, to find evaporators in a state of poor maintenance. For many evaporator units, the ice isn’t melted, or the water isn’t properly drained, resulting in a block of ice taking over the evaporator. When the coil freezes, heat transfer is greatly reduced resulting in the compressor working harder and longer. It works harder because the suction pressure drops making the compressor work at a higher differential pressure, thus requiring more power. It works longer because heat transfer is reduced. When ice buildup is excessive, the compressor will run all the time and the freezer temperature setpoint will not be maintained.

As the ice melts, the water has to drain out of the freezer. This doesn’t always occur. Trapped water that freezes can do significant structural damage to a freezer; especially older ones where cracks allow water to seep in, then freeze and expand. Stalactites and stalagmites of ice appearing in your freezer are reason for swift action to avoid costly damage.

Commercial Freezer Condensers

The condenser coil of the refrigeration system removes heat from the system. It’s not unusual to find condensers located in enclosed spaces or spaces with inadequate air flow to remove heat from the space. The temperature around the compressor rises resulting in higher head pressure for the compressor, which again increases compressor power.

To effectively remove heat, the condenser should be placed in a well-ventilated area where the temperature is controlled to allow heat to be removed easily. Enclosed spaces will require openings for cooling air intake and exhaust. In many cases, a fan will be required to move enough air through the space. If the condenser heat is never needed, it should be exhausted directly outside if possible.

In cases where it may be used for space heating — such as for a nearby dry storage room — controls may be installed to direct the flow indoors for heating, and outdoors when heating is not required.

Condenser coils should also be checked regularly for cleanliness. Dust and debris will act like ice buildup on an evaporator coil. This will insulate the heat transfer surface and reduce airflow, which will make the compressor run harder and longer. In extreme cases, compressors may fail.

Commercial Freezer Refrigerated Space & Shell

Although the space itself doesn’t have any mechanical parts or equipment, it shouldn’t be ignored. The shell of the cooler or freezer should be inspected regularly for leaks and loose insulation or panels. Leaks and other voids in the shell can cause excess moisture to accumulate, potentially causing even bigger problems. The door is also a key component of the cooler. Doors must be sealed properly to eliminate air infiltration which increases the cooling load and may cause moisture buildup within the space and on the evaporator. Frost buildup on the door itself is a common occurrence when the door heater fails and has a tendency to either freeze the door shut or keep it from closing. Proper care should also be taken when placing items inside the space. If the space is overcrowded with items, or items are placed in front of the evaporator fans, the circulation of air is greatly reduced along with the performance of the refrigeration system.

We hope the above diagnostic information helps you with any simple quick fixes that would help avoid trip charges and costly repairs. If however, you are not able to solve your Commercial freezer problems, please call SAC, Inc. We have over 20 years of experience and thousands of happy customers. In most cases we can respond to any type of service call the same day. We are available 24/7 so please call now.