OCILB – REFRIGERATION CONTRACTOR EXAM – QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED
ANSWERS | PLUS RATIONALES | DOWNLOAD AND PASS | LATEST EXAM UPDATE 2026/2027
CORE DOMAINS
Refrigeration Cycle, Heat Transfer, and Pressure–Temperature Relationships
Compressors, Condensers, Evaporators, Metering Devices, and System Components
Refrigerants, Charging, Recovery, Evacuation, and Leak Detection
Electrical Controls, Motors, Relays, Contactors, and Troubleshooting
Piping, Brazing, Insulation, and Installation Workmanship
Load Calculations, Equipment Selection, and Efficiency Considerations
Psychrometrics, Humidity Control, and Indoor Air Quality Fundamentals
Refrigeration/HVAC Codes, Mechanical Requirements, and Permit/Inspection Issues
Startup, Commissioning, Maintenance, and Diagnostic Procedures
Technician Safety, Including Electrical, Pressure, Refrigerant, and Combustion Hazards
INTRODUCTION
,The OCILB Refrigeration Contractor Examination is designed to assess the competency of candidates seeking licensure
as commercial refrigeration contractors in the State of Ohio. This examination evaluates both foundational knowledge
and applied professional judgment across the refrigeration trade, including system theory, component operation,
refrigerant handling, electrical controls, code compliance, and safety practices. Questions are presented in multiple-
choice and scenario-based formats that reflect real-world job site conditions and decision-making requirements.
Candidates must demonstrate not only technical recall but also the ability to interpret regulations, apply diagnostic
reasoning, and uphold ethical and professional standards. This assessment is structured to mirror the rigor and scope of
the actual licensing examination, preparing candidates for success in both testing and practice.
SECTION ONE: QUESTIONS 1–50
Question 1
A refrigeration system is operating with a suction pressure that is lower than normal and a discharge pressure that is
higher than normal. The compressor is running continuously. Which of the following is the most likely cause?
A. Refrigerant overcharge
B. Restricted liquid line or metering device
C. Compressor valve failure
D. Condenser fan motor failure
🟢 Correct Answer: B. Restricted liquid line or metering device
,🔴 Explanation: A restriction in the liquid line or at the metering device reduces refrigerant flow to the evaporator,
causing low suction pressure. Simultaneously, the compressor continues to draw refrigerant vapor, but with reduced
cooling load on the condenser, discharge pressure may rise if the condenser is not effectively rejecting heat.
Overcharge would typically elevate both pressures. Compressor valve failure would reduce pumping efficiency, often
lowering discharge pressure. Condenser fan failure would elevate discharge pressure but not directly cause low
suction pressure.
Question 2
Which of the following refrigerant types is classified as a hydrofluoroolefin (HFO) and has a low global warming
potential?
A. R-410A
B. R-134a
C. R-1234yf
D. R-22
🟢 Correct Answer: C. R-1234yf
🔴 Explanation: R-1234yf is an HFO refrigerant with a global warming potential of less than 1, making it
environmentally preferable to HFCs like R-410A and R-134a. R-22 is an HCFC with ozone-depleting potential. HFOs
are increasingly used in automotive and commercial refrigeration applications to meet environmental regulations.
, Question 3
A contractor is preparing to braze copper refrigerant lines. Which of the following practices is required to prevent
oxidation inside the tubing?
A. Use a flux paste on all joints
B. Purge the line with nitrogen during brazing
C. Heat the tubing to a cherry red color before applying filler
D. Apply water to the joint immediately after brazing
🟢 Correct Answer: B. Purge the line with nitrogen during brazing
🔴 Explanation: Nitrogen purging displaces oxygen inside the tubing, preventing the formation of copper oxide
scale during brazing. Scale can flake off and contaminate the system, leading to restrictions and compressor
damage. Flux is generally not used on copper-to-copper refrigerant joints. Overheating can damage the tubing, and
water quenching is not standard practice for refrigerant lines.
Question 4
A technician is diagnosing a walk-in cooler that is not maintaining temperature. The evaporator coil is iced over, and
the suction line is frosted back to the compressor. Which of the following is the most likely cause?
ANSWERS | PLUS RATIONALES | DOWNLOAD AND PASS | LATEST EXAM UPDATE 2026/2027
CORE DOMAINS
Refrigeration Cycle, Heat Transfer, and Pressure–Temperature Relationships
Compressors, Condensers, Evaporators, Metering Devices, and System Components
Refrigerants, Charging, Recovery, Evacuation, and Leak Detection
Electrical Controls, Motors, Relays, Contactors, and Troubleshooting
Piping, Brazing, Insulation, and Installation Workmanship
Load Calculations, Equipment Selection, and Efficiency Considerations
Psychrometrics, Humidity Control, and Indoor Air Quality Fundamentals
Refrigeration/HVAC Codes, Mechanical Requirements, and Permit/Inspection Issues
Startup, Commissioning, Maintenance, and Diagnostic Procedures
Technician Safety, Including Electrical, Pressure, Refrigerant, and Combustion Hazards
INTRODUCTION
,The OCILB Refrigeration Contractor Examination is designed to assess the competency of candidates seeking licensure
as commercial refrigeration contractors in the State of Ohio. This examination evaluates both foundational knowledge
and applied professional judgment across the refrigeration trade, including system theory, component operation,
refrigerant handling, electrical controls, code compliance, and safety practices. Questions are presented in multiple-
choice and scenario-based formats that reflect real-world job site conditions and decision-making requirements.
Candidates must demonstrate not only technical recall but also the ability to interpret regulations, apply diagnostic
reasoning, and uphold ethical and professional standards. This assessment is structured to mirror the rigor and scope of
the actual licensing examination, preparing candidates for success in both testing and practice.
SECTION ONE: QUESTIONS 1–50
Question 1
A refrigeration system is operating with a suction pressure that is lower than normal and a discharge pressure that is
higher than normal. The compressor is running continuously. Which of the following is the most likely cause?
A. Refrigerant overcharge
B. Restricted liquid line or metering device
C. Compressor valve failure
D. Condenser fan motor failure
🟢 Correct Answer: B. Restricted liquid line or metering device
,🔴 Explanation: A restriction in the liquid line or at the metering device reduces refrigerant flow to the evaporator,
causing low suction pressure. Simultaneously, the compressor continues to draw refrigerant vapor, but with reduced
cooling load on the condenser, discharge pressure may rise if the condenser is not effectively rejecting heat.
Overcharge would typically elevate both pressures. Compressor valve failure would reduce pumping efficiency, often
lowering discharge pressure. Condenser fan failure would elevate discharge pressure but not directly cause low
suction pressure.
Question 2
Which of the following refrigerant types is classified as a hydrofluoroolefin (HFO) and has a low global warming
potential?
A. R-410A
B. R-134a
C. R-1234yf
D. R-22
🟢 Correct Answer: C. R-1234yf
🔴 Explanation: R-1234yf is an HFO refrigerant with a global warming potential of less than 1, making it
environmentally preferable to HFCs like R-410A and R-134a. R-22 is an HCFC with ozone-depleting potential. HFOs
are increasingly used in automotive and commercial refrigeration applications to meet environmental regulations.
, Question 3
A contractor is preparing to braze copper refrigerant lines. Which of the following practices is required to prevent
oxidation inside the tubing?
A. Use a flux paste on all joints
B. Purge the line with nitrogen during brazing
C. Heat the tubing to a cherry red color before applying filler
D. Apply water to the joint immediately after brazing
🟢 Correct Answer: B. Purge the line with nitrogen during brazing
🔴 Explanation: Nitrogen purging displaces oxygen inside the tubing, preventing the formation of copper oxide
scale during brazing. Scale can flake off and contaminate the system, leading to restrictions and compressor
damage. Flux is generally not used on copper-to-copper refrigerant joints. Overheating can damage the tubing, and
water quenching is not standard practice for refrigerant lines.
Question 4
A technician is diagnosing a walk-in cooler that is not maintaining temperature. The evaporator coil is iced over, and
the suction line is frosted back to the compressor. Which of the following is the most likely cause?
