In short: read refrigerant type from the rating plate; never open the circuit yourself.

Glossary

Refrigerant: fluid carrying heat.
Compressor: raises vapour pressure.
Condenser: releases heat and forms liquid.
Expansion device: reduces pressure and controls flow.
Evaporator: absorbs room heat.
Condensate: water removed from humid air.
Defrost: clears evaporator frost.

Term	Definition
Refrigerant	The working fluid circulating through the system, absorbing and releasing heat as it boils and condenses. Some self-contained units use very-low-GWP R-290 propane; other systems use different refrigerants. Confirm the exact refrigerant and current regulatory GWP in the model data sheet and applicable rules.
Compressor	The "engine". It compresses refrigerant vapour, raising its pressure and temperature so the cycle can run.
Condenser	Where the refrigerant rejects heat to the outside air and condenses from gas to liquid. Located outside the cold space; keeping its coil clean is essential. See Condenser maintenance
Expansion valve	A restriction that drops the refrigerant's pressure just before the evaporator. The pressure drop produces the temperature drop that makes the refrigerant cold enough to absorb heat.
Evaporator	The unit inside the room where refrigerant absorbs heat from the air and boils back to vapour. This is where cooling actually happens; a fan circulates the chilled air.
Condensate	Water that forms when humid air meets the cold evaporator. Collected in a drip tray and drained away; a blocked drain is a frequent cause of ice build-up.
Defrost	The cycle that clears ice from the evaporator — electric (heater elements), hot-gas (briefly routing hot refrigerant through the coil), or off-cycle (simply pausing refrigeration).

For how these components work together, see How cold rooms work.

Missing a term, or need a specification confirmed for your project? Contact [email protected].

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