Effect of a dirty condenser coil
The refrigeration equipment appears to be running yet the case temperature is still too warm. In order for the refrigeration system to absorb heat from the inside of the cooler, it must be able to discharge the heat it absorbs. Restricted air flow will cause the condenser pressure to climb and reduce the net refrigeration effect. On an air-cooled system, this is done through the condenser coil on the front of the unit. If it is a water-cooled unit the heat is discharged through a coil into the water. An air-cooled system gets very dirty in a commercial kitchen and must be clean regularly. The air born grease particles makethe fins very sticky, and the fin coils can clog up very quickly. Brushing the face off every month with a wire brush. This will help keep it clean if it's down frequently. A more extensive cleaning may still be required annually and chemically cleaned to remove the grease. Look closely between the fins of the condenser. This is where the dirt can collect unnotice. Even if the face of the coil appears to be clean the unit can be completely plugged. The dirt builds up on the air inlet side of the coil. Make sure you are looking at the correct side of the coil. The air discharge side will appear to be clean. Most refrigeration systems draw the air through the coil and discharge out the rear over the compressor. By measuring the air temperature blowing from the condenser you can tell how dirty your condenser is. If it is more than 25F° higher than the room temperature, then you have a problem. You can clean the coil by blowing the coil clear with compressed air or CO2. Blow in the opposite direction of the airflow. "DO NOT BLOW THE DIRT DEEPER INTO THE COIL". I normally place a garbage bag over the coil before blowing it out. This is to catch some of the dirt that will come out of the coil. Even with that, you can still make real mess. Make sure any food surfaces nearby are covered and preferably when the ktichen or store is closed. If the unit appears to be clean and the unit is still running hot, then check the air supply to the condenser. The air must be drawn into one side of the unit and discharge away from the unit on the other side, with out being drawn back into the condenser. If the condenser does not have enough air or a source of cool air to supply the condenser it will have the same effect as a plugged coil. If the air short cycles, drawing it's own discharge air back into the intake, the unit will overheat. Make sure the air being drawn into the coil is clean and cool.
Keeping the coil clean and the air intake cool will increase the overall efficiency and extend the life of the equipment. This can reduce the heat load of the store, which will help reduce the demand on the air conditioning.
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