EPA 609 MVAC System Components & Operation 1 — Questions and Answers
Question 1: What is the primary function of the compressor in an MVAC system?
- To cool the refrigerant by removing heat
- To pressurize refrigerant vapor and circulate it through the system (Correct answer)
- To filter moisture from the refrigerant
- To regulate refrigerant flow into the evaporator
Correct answer: To pressurize refrigerant vapor and circulate it through the system
The compressor pumps and pressurizes refrigerant vapor, raising its temperature before it enters the condenser to release heat.
Question 2: Where does heat absorption (cooling of the vehicle cabin) occur in an MVAC system?
- Condenser
- Compressor
- Receiver-drier
- Evaporator (Correct answer)
Correct answer: Evaporator
The evaporator is located inside the vehicle cabin where liquid refrigerant absorbs heat by evaporating, cooling the air blown over it.
Question 3: What is the function of the condenser in an MVAC system?
- To evaporate liquid refrigerant inside the cabin
- To release heat from the refrigerant to the outside air (Correct answer)
- To filter refrigerant contaminants
- To compress refrigerant vapor
Correct answer: To release heat from the refrigerant to the outside air
The condenser, located in front of the radiator, releases the heat absorbed from the cabin to the outside air, converting refrigerant vapor back to liquid.
Question 4: What device in an MVAC system controls the flow of refrigerant into the evaporator?
- Compressor clutch
- Thermal Expansion Valve (TXV) or Orifice Tube (Correct answer)
- Receiver-drier
- Suction accumulator
Correct answer: Thermal Expansion Valve (TXV) or Orifice Tube
A TXV or orifice tube meters liquid refrigerant into the evaporator, maintaining the correct pressure drop for proper evaporation.
Question 5: The high-pressure side of an MVAC system runs between which components?
- Evaporator outlet to compressor inlet
- Compressor outlet to evaporator inlet (through condenser) (Correct answer)
- Receiver-drier to evaporator
- Compressor to accumulator
Correct answer: Compressor outlet to evaporator inlet (through condenser)
The high-pressure side runs from the compressor outlet through the condenser and to the metering device inlet.
Question 6: What is the purpose of the receiver-drier (or accumulator) in an MVAC system?
- To compress refrigerant vapor
- To store liquid refrigerant and remove moisture and contaminants (Correct answer)
- To measure system pressure
- To cool the cabin air directly
Correct answer: To store liquid refrigerant and remove moisture and contaminants
The receiver-drier stores excess liquid refrigerant and contains desiccant to absorb moisture that could cause acid formation and system damage.
EPA 609 MVAC System Components & Operation 1
What is the primary function of the compressor in an MVAC system?