HVAC Skills and Knowledge

An HVAC system with low superheat and low subcooling typically indicates:

• a) A refrigerant overcharge

• b) A refrigerant undercharge

• c) A malfunctioning compressor

• d) A blocked expansion valve

Which of the following is a primary function of a pressure-enthalpy diagram in refrigeration?

• Analyze refrigerant properties

• Calculate energy efficiency

• Determine compressor size

• Measure temperature fluctuations

What is the most likely cause of a short cycling compressor?

• a) High ambient temperature

• b) Low refrigerant charge

• c) Faulty thermostat

• d) Clogged air filter

What is the function of a thermostatic expansion valve (TXV)?

• a) Control the temperature of the refrigerant

• b) Measure the pressure of the refrigerant

• c) Regulate refrigerant flow based on superheat

• d) Increase the refrigerant's pressure before entering the condenser

What device protects an HVAC system from excessive electrical current?

• Fuse

• Transformer

• Capacitor

• Relay

A liquid receiver is typically installed:

• a) Between the evaporator and compressor

• b) Between the condenser and expansion valve

• c) Between the compressor and condenser

• d) At the outlet of the expansion valve

What safety procedure should always be followed when working with refrigerants?

• Wear personal protective equipment (PPE)

• Use a fan to disperse refrigerants

• Work in a poorly ventilated area

• Ignore manufacturer guidelines

What type of refrigerant is most commonly used in modern residential air conditioning systems?

• R-22

• R-134A

• R-410A

• R-404A

What is the function of a variable frequency drive (VFD) in an HVAC system?

• Control motor speed

• Regulate temperature

• Filter air quality

• Monitor humidity levels

What is the primary purpose of a vacuum pump in an HVAC system?

• To increase the pressure of refrigerant

• To remove moisture and non-condensables

• To circulate air within the system

• To cool the refrigerant before expansion