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maintenance plans

Refrigeration Equipment, Procedures & Parts Explained

Leak Test

– Is done by checking over the refrigerant circuit for gas leaking from the system. There are several methods, electronic leak detectors, bubbles, pressure testing.

Pressure Test

– Pressure testing the system is done by pressurising the refrigerant system with dry nitrogen and ensure it maintains a constant pressure over time. This ensures that there is no gas leaks.


– Overload is a protection device found on most motors and compressors, this device stops the motor or compressor from exceeding its rated current draw.

Gas Leak

– A gas leak can only occur if there is a hole or crack in the refrigerant system.


– Refrigeration gas is usually non flammable and odorless. A refrigeration system does not require re gassing unless the gas has leaked out. A refrigeration system does not consume gas like a bbq it is recirculated around the refrigeration system over and over.

Vibration Eliminator

– A vibration eliminator is a piece of copper line to allows small movement of the pipework to eliminate the likelihood of a pipe cracking and leaking gas.


– The role of a Accumulator is to protect the compressor against the return of liquid.This is done by liquid filling accumulator and vapor taken from the top is returned to compressor.

Air Off

– The term air off means the air temperature off the evaporator coil or condenser coil.

Air On

– This is the air to be pulled/pushed through the evaporator or condenser coil. Also known as return air.

Ambient Temperature

– In Refrigeration & A/C ambient temperature is the air temperature surrounding the equipment.


– Ampere is a measure of the amount of electric charge passing a point in a electric circuit. Electric components have a rated full load amps.


– A capacitor is a passive two-terminal electrical component used to store energy electrostatically in an electric field. Commonly used to start motors.


– Capillary tube is one of the most commonly used metering devices in refrigeration and air conditioning systems. The capillary tube is a tiny copper tube with internal diameter and length to match capacity of the refrigeration.

Cascade System

– Arrangement of two or more refrigeration systems used in series. The evaporator of one unit is used to cool the condenser of another. Generally used to obtain very low temperatures or cool systems with high condenser temperatures/pressures.


– A compressor in a refrigeration system draws vapor from the evaporator and compresses the gas into high pressure, low volume and delivers it to condensing side of the system. One of the most important characteristics of a refrigeration compressor is the capacity of the system. Compressor are sized on the basis of the refrigeration capacity, refrigerant type and temperature conditions.

Types of compressors

– Centrifugal – Hermetic – Open Drive – Reciprocating – Rotary – Screw – Scroll – Semi Hermetic


– Is the radiator looking coil usually found outside near the compressor. A Condenser is a heat transfer device that receives high pressure vapour at a temperature higher than the cooling medium, such as air or water, to which the condenser passes the latent heat from the refrigerant, causing the vapor to liquify.


– A contactor is an electrically controlled switch used for switching a power circuit, similar to a relay except with higher current ratings.

Defrost Cycle

– A cycle in the control circuit of refrigeration which allows cooling off time.This is to remove ice build ups on evaporator coils. Some systems also use electric or hot gas heating of the coil.


– The temperature difference between cut-in temp and cut-out temp of a thermostat.


– A component of the refrigeration system (synonymous with dehydrator) used to remove moisture from the refrigeration system. If a refrigeration system is opened to atmosphere, this should be changed.


– Removal of air and moisture from a refrigeration system. This is done with a vacuum pump to 500mircons. This is performed every time system is opened to atmosphere.


– The evaporator is the part inside the fridge that blows the cold air or a device in which refrigerant evaporates while absorbing heat.

Expansion Valve

– TX Valve – A device which regulates the flow of a refrigerant into the evaporator to maintain a constant pressure/temperature. Usually found mounted inside the evaporator.

Flood Back

– Flooding – The results of liquid refrigerant from the evaporator entering the compressor. A damaged refrigerant control, iced up evaporator or poorly commissioned system often leads to flooding of the compressor.


– Hydrochlorofluorocarbons are halogenated compounds containing carbon, hydrogen, chlorine and fluorine. Now being phased out globally. eg. (r22).

Head Pressure

– The pressure in the compressor head, condenser and liquid line. Often high due to poor maintenance of condenser and high ambient temperatures.

Pressure Control

– HP/LP – A control device that is connected to the high and low side of the system which cuts out the refrigeration process when pressure is too high or low. Its purpose is to protect the refrigeration equipment.


– Hydrofluorocarbon, any of several organic compounds composed of hydrogen,fluorine, and carbon. HFCs are produced synthetically and are used primarily as refrigerants. eg. R134a.

Low Side

– The part of the refrigeration system which normally operates under low pressure. eg. Evaporator.


– A device used to convert electrical energy into a rotating motion.

Motor Shaded Pole

– An induction motor that develops a rotating magnetic field by shading part of the stator winding with a shading loop.

Motor Split Phase

– A type of single phase motor the use resistance or capacitance to cause a shift in the phase of the current in the run winding and the current in the start winding, eg. resistance-start induction-run, capacitor-start induction-run and permanent split capacitor.

Compressor Efficiency Test

– Is checking pumping performance of compressor. If compressor fails this test it will not operate to its full capacity and require replacement.

Oil Separator

– A device to separate oil from high pressure vapor from the compressor. Usually contains a float valve to return oil to the crankcase.

Pump Down

– Is the closure of the liquid line, with a solenoid valve, when the thermostat is satisfied in a refrigeration system. The compressor then pumps the refrigerant into a receiver tank. Also shutting the liquid line receiver service valve with pump down the unit.


– Tetrafluoroethane, R-134a is a haloalkane refrigerant with thermodynamic properties similar to R12 dichlorodifluoromethane but with insignificant ozone depletion potential. It has a boiling point of −26.3 °C at atmospheric pressure. R-134a cylinders are coloured light blue.


– Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon (HCFC). This colourless gas is better known as R-22. It is commonly used as refrigerant. These applications are being phased out in developed countries due to the compound’s ozone depletion potential (ODP) and high global warming potential (GWP), although global use of R-22 continues to increase because of high demand in developing countries.R-22 cylinders are coloured green.


– R404A is a blend of HFC refrigerants commonly used for medium and low temperature refrigeration applications. It’s composition comprises: HFC-125 (44%), HFC-143a (52%), HFC-134a (4%). Brown cylinder.


– R407C is a blend of HFC refrigerants designed to replace R22 in air conditioning applications. It’s composition comprises of HFC-32 (23%), HFC-125 (25%), HFC-134a (52%). Brown Cylinder.


– R410A is a blend of HFC refrigerants commonly used for air conditioning applications. It’s composition comprises: HFC-125 (50%), HFC-32 (50%). Pink Cylinder.

Refrigerant or Gas

– The medium of heat transfer in a refrigeration system, which absorbs heat by evaporating at low temperatures and gives up heat by condensing at higher temperatures.


– A system in which refrigerant is circulated for the purpose of extracting heat.

Service Valve

– Access point in a refrigeration system with service ports to fit gauges, charge and recover refrigerant. Commonly found on compressor and liquid receivers.

Short Cycling

– The starting and stopping of a compressor in short succession. Usually caused by compressor overload or pressure control.

Sight Glass

– An indicator with a glass window use to inspect the state of refrigerant.

Solenoid Valve

– A electric coil with mechanical valve used in refrigeration to start or stop refrigerant passing through where fitted. Commonly used for pump down or hot gas bypass.


– The difference between the heat contained in a vapor and the actual temperature of the refrigerant exiting the evaporator coil. This is set on the TX Valve during commissioning of the system and is vital to your system operating correctly.


– A temperature actuated switch, that controls the refrigeration system by switching it on or off with regards to the set temperature.


– A plate in the compressor containing the suction and discharge valves that separates each port during the stroke of the piston.