LOUISIANA (NEW ORLEANS) SECOND CLASS STATIONARY AIR CONDITIONING - 640-LA CONTRACTOR
EXAM QUESTIONS AND ANSWERS ALREADY GRADED A+. 100% Verified Solutions | Updated Per Latest
Guidelines | Graded A+...
CORE DOMAINS
Refrigeration Cycle Theory and Thermodynamics
System Components: Compressors, Condensers, Evaporators, Metering Devices
Electrical Systems, Controls, Motors, and Wiring Schematics
Psychrometrics and Air Distribution
Heating Systems and Heat Pumps
System Diagnostics, Troubleshooting, and Maintenance
Piping Practices, Refrigerant Handling, and Safety
Load Calculations and System Sizing
Installation Codes and Standards (IMC, NEC, ASHRAE)
Louisiana State Contractor Laws and Regulations
This practice assessment is designed for candidates preparing for the Louisiana (New Orleans) Second Class
Stationary Air Conditioning Contractor Examination. The examination evaluates the technical competencies
,required to install, maintain, repair, and troubleshoot commercial and industrial air conditioning and refrigeration
systems up to the limits of this license classification. Key skills assessed include interpreting electrical schematics
and wiring diagrams, performing accurate psychrometric analysis, diagnosing mechanical and electrical faults
using systematic reasoning, and ensuring compliance with the International Mechanical Code, National Electrical
Code, and local Louisiana regulations. Questions utilize realistic field scenarios requiring professional judgment,
safety consciousness, and applied critical thinking. The format consists of 100 original multiple-choice questions
distributed across all core domains, reflecting the cognitive demands of the live examination, from fundamental
knowledge through complex scenario-based problem-solving.
SECTION ONE
Question 1
What is the primary function of the metering device in a mechanical vapor-compression refrigeration system?
A. To compress the refrigerant vapor from low to high pressure
B. To reject heat from the refrigerant to the outdoor air
C. To provide a pressure drop that regulates refrigerant flow and lowers boiling point
D. To absorb heat from the conditioned space into the refrigerant
🟢 Correct Answer: C
🔴 RATIONALE: The metering device—whether a thermostatic expansion valve, capillary tube, or piston—
creates a pressure differential between the high and low sides. This sudden pressure drop lowers the saturation
,temperature of the refrigerant, allowing it to boil and absorb heat in the evaporator. Compression, heat
rejection, and heat absorption are functions of the compressor, condenser, and evaporator respectively.
Question 2
A technician measures an evaporator superheat of 5°F and a condenser subcooling of 10°F on a fixed-orifice
system. How should the system's charge be interpreted?
A. Overcharged
B. Undercharged
C. Correctly charged based on subcooling
D. Cannot be determined without the manufacturer's chart
🟢 Correct Answer: D
🔴 RATIONALE: On a fixed-orifice system, the correct refrigerant charge is verified primarily using the
manufacturer’s specified superheat value for the given indoor and outdoor conditions. Subcooling alone is not
the primary charging metric for this metering device type. The technician must consult the charging chart to
determine if 5°F superheat is acceptable at the measured temperatures.
Question 3
, According to the International Mechanical Code, what is the minimum required access opening for an attic
containing an air handler rated at 60,000 Btu/h?
A. 20 inches by 30 inches
B. 22 inches by 30 inches
C. 24 inches by 36 inches
D. 30 inches by 30 inches
🟢 Correct Answer: B
🔴 RATIONALE: IMC Section 306.3 specifies that an attic containing equipment requiring service shall have an
access opening of at least 22 inches by 30 inches. This provides sufficient clearance for a technician to enter and
perform maintenance on the equipment. Larger dimensions apply to specific equipment sizes, but 22" x 30" is
the base minimum.
Question 4
Which type of compressor is classified as a positive displacement compressor that uses two interlocking
rotating elements to compress refrigerant?
A. Centrifugal compressor
B. Reciprocating compressor
C. Scroll compressor
D. Screw compressor
EXAM QUESTIONS AND ANSWERS ALREADY GRADED A+. 100% Verified Solutions | Updated Per Latest
Guidelines | Graded A+...
CORE DOMAINS
Refrigeration Cycle Theory and Thermodynamics
System Components: Compressors, Condensers, Evaporators, Metering Devices
Electrical Systems, Controls, Motors, and Wiring Schematics
Psychrometrics and Air Distribution
Heating Systems and Heat Pumps
System Diagnostics, Troubleshooting, and Maintenance
Piping Practices, Refrigerant Handling, and Safety
Load Calculations and System Sizing
Installation Codes and Standards (IMC, NEC, ASHRAE)
Louisiana State Contractor Laws and Regulations
This practice assessment is designed for candidates preparing for the Louisiana (New Orleans) Second Class
Stationary Air Conditioning Contractor Examination. The examination evaluates the technical competencies
,required to install, maintain, repair, and troubleshoot commercial and industrial air conditioning and refrigeration
systems up to the limits of this license classification. Key skills assessed include interpreting electrical schematics
and wiring diagrams, performing accurate psychrometric analysis, diagnosing mechanical and electrical faults
using systematic reasoning, and ensuring compliance with the International Mechanical Code, National Electrical
Code, and local Louisiana regulations. Questions utilize realistic field scenarios requiring professional judgment,
safety consciousness, and applied critical thinking. The format consists of 100 original multiple-choice questions
distributed across all core domains, reflecting the cognitive demands of the live examination, from fundamental
knowledge through complex scenario-based problem-solving.
SECTION ONE
Question 1
What is the primary function of the metering device in a mechanical vapor-compression refrigeration system?
A. To compress the refrigerant vapor from low to high pressure
B. To reject heat from the refrigerant to the outdoor air
C. To provide a pressure drop that regulates refrigerant flow and lowers boiling point
D. To absorb heat from the conditioned space into the refrigerant
🟢 Correct Answer: C
🔴 RATIONALE: The metering device—whether a thermostatic expansion valve, capillary tube, or piston—
creates a pressure differential between the high and low sides. This sudden pressure drop lowers the saturation
,temperature of the refrigerant, allowing it to boil and absorb heat in the evaporator. Compression, heat
rejection, and heat absorption are functions of the compressor, condenser, and evaporator respectively.
Question 2
A technician measures an evaporator superheat of 5°F and a condenser subcooling of 10°F on a fixed-orifice
system. How should the system's charge be interpreted?
A. Overcharged
B. Undercharged
C. Correctly charged based on subcooling
D. Cannot be determined without the manufacturer's chart
🟢 Correct Answer: D
🔴 RATIONALE: On a fixed-orifice system, the correct refrigerant charge is verified primarily using the
manufacturer’s specified superheat value for the given indoor and outdoor conditions. Subcooling alone is not
the primary charging metric for this metering device type. The technician must consult the charging chart to
determine if 5°F superheat is acceptable at the measured temperatures.
Question 3
, According to the International Mechanical Code, what is the minimum required access opening for an attic
containing an air handler rated at 60,000 Btu/h?
A. 20 inches by 30 inches
B. 22 inches by 30 inches
C. 24 inches by 36 inches
D. 30 inches by 30 inches
🟢 Correct Answer: B
🔴 RATIONALE: IMC Section 306.3 specifies that an attic containing equipment requiring service shall have an
access opening of at least 22 inches by 30 inches. This provides sufficient clearance for a technician to enter and
perform maintenance on the equipment. Larger dimensions apply to specific equipment sizes, but 22" x 30" is
the base minimum.
Question 4
Which type of compressor is classified as a positive displacement compressor that uses two interlocking
rotating elements to compress refrigerant?
A. Centrifugal compressor
B. Reciprocating compressor
C. Scroll compressor
D. Screw compressor
