AMBIENT SWITCH: Describes a type of sensing switch that monitors outside air temperature an prevents the operation of a vehicle's compressor and recirculating air mode when outside temperatures fall below 5°C.

ACCUMULATOR DRIER:Describes a part of a vehicle's air conditioning system made up of a tank, filter, drying agent, and a vapour return tube that stores excess refrigerant and removes moisture from the refrigerant.

ELECTRONIC CLIMATE CONTROL (ECC): Describes an air conditioning system control which determines and maintains the pre-determined temperature in the passenger compartment.

EVAPORATOR: Describes the unit in an air conditioning system used to transform refrigerant from a liquid to a gas, to allow air cooling takes place as heat is removed.

FIXED ORIFICE TUBE: Describes a device that converts high pressure liquid refrigerant into low pressure before it passes through the evaporator.

FLOW-THROUGH VENTILATION: Describes a system which allows outside air into the passenger compartment through the dash and rear quarter panels.

FREEZE-UP: Describes the failure of a unit to operate to its maximum as a result of the formation of ice at the expansion valve orifice or on the evaporator coils.

FREON: Describes a type of gas used as the cooling medium in older air conditioning and refrigeration systems.

HEATED REAR WINDOW Describes a rear window with an integral heating element that demists (defogs) inside and defrosts (de-ices) the outside.

HEATED WINDSHIELD: Describes a device that cuts off the compressor when the evaporator temperature drops below a certain level.

IN-CAR SENSOR: Describes a dual bimetal strip designed to maintain a constant temperature in the passenger compartment through a vacuum modulator that controls the heating or air conditioner blend door.

LEAK DETECTOR: Describes a device used to detect leaks in an air conditioning system.

LOW-PRESSURE CUT-OUT: Describes a device that protects the air conditioning system by cutting power to the compressor in the event of a sudden pressure loss

OPERATIONAL TEST: Describes tests on an air conditioner to determine whether temperature, pressure, and other conditions under controlled circumstances are operating optimally.

PLENUM CHAMBER: Describes the air compartment in a car body formed between the scuttle and the bulkhead, that provides the basis for interior air supply.

RECEIVER-DEHYDRATOR: Describes a form of storage tank and filter for handling liquid refrigerant that contains a drying agent to remove moisture from circulating refrigerant.

REFRIGERATION CYCLE: Describes a complete circulation of refrigerant through an air conditioning system as it changes temperature and pressure that changes its state from vapour to liquid, then back to vapour.

RELIEF VALVE: Describes a valve in the air pump of an air injection system that releases part of the air at high pump speeds in order to prevent pump damage.

SECONDARY AIR: Describes a situation that occurs in certain exhaust emission control systems where air is added to the exhaust to ensure sufficient supply of oxygen to promote oxidation of HC and CO, in the process converting these potential pollutants into water vapour and carbon dioxide.

SERVICE HOSE: Describes a special hose, designed and manufactured to withstand the operating pressures of an air conditioner system, equipped with threaded fittings that can be attached to service valves, manifold gauge sets, vacuum pumps and refrigerant containers.

SIGHT GLASS: Describes a viewing window found in the refrigerant pipe of a vehicle's air-conditioning system that allows a visual check of the flow of refrigerant passing from the receiver to the evaporator.