| Manifold gauge set | | Term for a refrigerant that can be mixed with the existing refrigerant in an air conditioner. |
| Performance test | | Air-conditioning hose with an internal liner to prevent the escape of R-134a refrigerant. |
| Miscible | | Refrigerant used in the air conditioning systems of most vehicles manufactured after 1992. Replaced R-12 due to environmental concerns |
| Schrader valve | | An electrically operated instrument used to test air conditioning system for refrigerant leaks. |
| Refrigerant | | Unit in air conditioning system used to transform refrigerant from a liquid to a gas. It is at this point that cooling takes place. |
| Phosgene gas | | Checks the refrigerant and heating system components for proper pressures and temperatures. |
| Blend door | | Refrigeration system with a fixed (does not change size) orifice tube. Evaporator pressure is controlled by turning the compressor clutch on and off |
| Blended refrigerant | | Refrigerant used in older air conditioning systems. Gradually being replaced by R-134a in newer vehicles. |
| Barrier hose | | Unit in air conditioning system that cools hot compressed refrigerant and turns it from vapor into liquid. |
| Muffler | | Finned device for heating vehicle interiors. Resembles a small radiator |
| Functional test | | Door installed in the air conditioning blower case. Controls temperature of the air going to the passenger compartment. |
| Condenser | | Removal of air. |
| Drop-in refrigerant | | An electromagnet that draws the clutch hub inward, locking the revolving pulley to the compressor shaft |
| Vacuum pump | | Process of converting an air-conditioning system that uses R-12 to handle R-134a refrigerant. |
| Orifice tube | | Air conditioning system switch that cuts off the refrigeration system pressure if the pressure becomes so high that the compressor could be damaged or refrigerant lost. |
| Refrigerant oil | | Having the ability to absorb moisture from air. |
| Accumulator | | A manifold assembly containing two pressure gauges (one high, one low), two gauge valves, and three outlet connections. Used to service (discharge, charge, evacuate) air conditioning system |
| Heater core | | To reuse a portion or all the refrigerant taken from a refrigerant system. |
| Air Conditioning | | Type of restrictor used to control refrigerant flow between the condenser and evaporator |
| Cycling clutch Orifice | | A microorganism killer. |
| R12 | | Liquid used in refrigeration systems to remove heat from evaporator coils and carry it to condenser |
| R134a | | Diaphragm pump used to produce vacuum. |
| Refrigerant Recycling | | This switch opens and closes the electrical circuit to the clutch based on low-side pressure. |
| R22 | | System used to control the temperature, movement, cleanliness and humidity of air in a vehicle |
| Evaporator | | Valve designed to open at specific pressure. This will prevent pressures in system from exceeding certain limits |
| Retrofitting | | Type of restrictor that the entrance of liquid refrigerant into the evaporator is controlled by varying the opening of the expansion valve, based on the temperature at the evaporator outlet |
| Service fittings | | Often placed between compressor and condenser to reduce pumping noise. |
| Boiling point | | Significant New Alternatives Program of the Environmental Protection Agency. A program to identify refrigerants that can be used to replace R-12. Refrigerants found acceptable for their impact on global warming might not perform well in an air conditioning system. |
| SNAP program | | Switch that cuts off the refrigerant system pressure if the pressure becomes so low that the compressor could be damaged. |
| Hygroscopic | | Process of removing oxygen from an air conditioning system by pumping air out of the system, creating a vacuum |
| High-pressure Cutoff switch | | Valve that stops the flow of engine coolant through the heater core when heating is not needed. |
| Evacuating | | Exact temperature at which a liquid begins to boil. |
| Evaporator pressure control | | Resistor that changes its resistance in relation to temperature. |
| Electronic leak Detector | | Refrigerant used in commercial cooling applications. |
| Thermistors | | Device used to raise pressure of refrigerant in an air conditioning system. Also causes refrigerant to flow through system. |
| Pressure cycling switch | | Pressure-regulating valves. |
| Compressor | | Check for proper system operation at different settings. |
| Thermostatic expansion valve | | Refrigerant made with two or more chemical compounds |
| Shut off valve | | A very toxic (poisonous) gas. Can be formed when refrigerant is exposed to an open flame. |
| Pressure relief valve | | Valve, similar to spring-loaded valve used in tire stem, used in car air conditioning and fuel injection system service valves. |
| Purging | | Special oil that lubricates air conditioning compressor. |
| EPA | | A federal agency concerned with air, water, and ground pollution reduction. |
| Compressor clutch | | Fittings that connect the refrigeration system to the service hoses. |
| Low- pressureCutoff switch | | Receiver-dehydrator combination. |
| Biocide | | Oil that can be mixed and be carried with the refrigerant to lubricate moving parts. |
