| A | B |
|---|
| relay | electro-mechanical switching device |
| contactor | controls compressor operation |
| thermostat | controls the entire system |
| sequencer | controls electric heaters |
| thermal time delay relay | another name for sequencer |
| crankcase heater | keeps compressor warm |
| reversing valve | changes heatpump from heat to cool |
| compressor | pumps refrigerant vapor |
| condensor | gas changes to liquid |
| evaporator | liquid boils to a gas |
| check valve | regulates refrigerant flow direction |
| indoor blower | circulates inside air |
| outdoor fan | moves air across outside coil |
| refrigerant | substance that absorbs heat |
| transformer | supplies control voltage |
| low pressure switch | protects compressor |
| high pressure switch | compressor safety switch |
| fuse | safety overload device |
| manifold gage | used to check, remove, or add refrigerant |
| run capacitor | improves motor efficiency |
| start capacitor | boosts starting torque |
| VOM | volt-ohm meter |
| ammeter | measures amperage |
| multimeter | measures voltage, ohms, ect. |
| amperage | current |
| electricity | electrons flowing |
| ohms | measure of resistance |
| voltage | electrical pressure |
| freon | trade name for refrigerant |
| heat pump | heats and cools |
| gas furnace | heating unit only |
| circuit | complete path for electron flow |
| parallel circuit | more than one path for electricity |
| series circuit | only one path for current |
| circuit breaker | safety overload device that can be reset |
