ABYC Air Conditioning & Refridgeration Certification Exam Review Questions With Correct Answers!!

The weight of water vapor in a given amount of air (Grains per cubic foot) - Answer-Absolute Humidity Pressure measured with a base of zero - Answer-Absolute Pressure A temperature scale using absolute zero as a reference - Rankin or Kelvin Scale (may be measures in degrees C or F) - Answer-Absolute Temperature Theoretical temperature at which all molecular activity ceases = -273.16 C or -456.69 F - AnswerAbsolute Zero By approximately how much (%) does a start capacitor increase motor torque? - Answer-250% Tech A says that it is possible to identify the start and run windings of a motor with an ohm meter by noting which has higher resistance, indicating the start windings. Tech B say the highest resistance will be noted when measuring from run to start terminals. Which is correct? A. Tech A B. Tech B C. Both D. Neigher - Answer-C. Both The heart of a system, keeps the refridgerant flowing at specific rates of flow, at specific temperatures. - Answer-Compressor On which side of a compressor is the low pressure switch, inlet or outlet, and what function does it provide? - Answer-Inlet (suction), shuts down system if pressure drops too low.On which side of a compressor is the high pressure switch, inlet or outlet, and what function does it provide? - Answer-Outlet, shuts down compressor if pressure gets too high (to protect the compressor). Air or water cooled heat exchanger which absorbs latent heat energy of hot refridgerant gas and causes it to become a liquid. - Answer-Condenser Maintains a specific rate of flow from the high-pressure side of a refridgeration system into the lowpressure side. - Answer-Metering Device (AKA Expansion Device/Tube/Valve, TXV, or Capillary Tube) Air heat-exchanger that allows heat from incoming air to pass into the cold refridgerant liquid which absorbs latent heat and evaporates in the process, cooling the exit air. - Answer-Evaporator Trademark for a popular manufacturer of compressor overload protector device. (Also manufactures overcurrent protection devices, switches, and thermostats used in HVAC systems) - Answer-KLIXON overload protector What is a common cause of motor winding insulation leakage/breakdown? - Answer-Running at lower than rated voltage (increases current draw and thus temperature of windings) 1 Watt is equal to how many BTU's per hour? - Answer-3.412 BTU's/Hour = 1 Watt 1 BTU per hour is equal to how many Watts? - Answer-1 BTU / hr = 0.293 Watts When calculating power draw for a motor, Tech A says to multiply Amps by Volts. Tech B says this is true, but it would be more accurate to include a third multiplier, Power Factor to give accurate real power draw. Who is most correct? - Answer-Tech B (motors have PF < 1) Another name for Start Relay - Answer-Potential Relay Ho much bigger should an air conditioning return duct be compared to the discharge duct? - Answerreturn should be 20% bigger than source At what height should A/C discharge ducts be located in the cabin? - Answer-Waist heigh or higherAt what height should A/C return duct sources be located in the cabin? - Answer-low, near the floor Why should A/C condensate drain hose not be discharged into the engine room bilge area? - Answerrisk of CO ingress What is the minimal distance on the outside of the hull between A/