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100+ Free MS Refrigeration Practice Questions

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2026 Statistics

Key Facts: MS Refrigeration Exam

70%

Passing Score

PSI MS Contractor Bulletin 4/23/2026

50 Q

Official Exam Questions

PSI MS Contractor Bulletin 4/23/2026

2 hours

Time Allowed

PSI MS Contractor Bulletin 4/23/2026

$120

PSI Exam Fee

PSI MS Contractor Bulletin 4/23/2026

Open book

Exam Format

PSI MS Contractor Bulletin 4/23/2026

MS Refrigeration PSI trade exam: 50 questions, 70% pass, 2 hours, fee $120. Open-book MSBOC classification (bulletin 4/23/2026).

Sample MS Refrigeration Practice Questions

Try these sample questions to test your MS Refrigeration exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a vapor-compression refrigeration cycle, the four essential components in flow order starting at the compressor discharge are the:
A.Evaporator, compressor, expansion device, and condenser
B.Condenser, expansion device, evaporator, and compressor suction
C.Expansion device, condenser, receiver, and evaporator
D.Oil separator, evaporator, condenser, and compressor
Explanation: Hot high-pressure discharge gas first rejects heat in the condenser and leaves as high-pressure liquid. The expansion device then drops pressure, the evaporator absorbs heat at low pressure, and vapor returns to the compressor suction to complete the cycle. That component order is the foundation of every commercial and industrial vapor-compression plant.
2The compressor in a refrigeration system primarily:
A.Rejects heat from the refrigerant to the outdoor air or condenser water
B.Meters liquid refrigerant into the evaporator
C.Raises refrigerant vapor pressure and temperature so heat can be rejected
D.Separates oil from liquid refrigerant in the receiver
Explanation: The compressor takes low-pressure suction vapor and delivers it at a higher pressure and temperature. That lift creates the temperature difference that lets the condenser reject heat to air or water. Without the pressure rise, the cycle cannot move heat from a cold space to a warmer sink.
3One ton of refrigeration is defined as a heat-removal rate of:
A.1,000 Btu per hour
B.144,000 Btu per hour
C.200 Btu per hour
D.12,000 Btu per hour
Explanation: One ton equals 12,000 Btu/h, the heat absorbed when one short ton of ice melts in 24 hours (2,000 lb × 144 Btu/lb ÷ 24 h). In rate form it is also 200 Btu/min. U.S. commercial and industrial equipment capacity is still rated in tons.
4Evaporator superheat is best defined as:
A.The number of degrees a refrigerant vapor is above its saturation temperature at the measured suction pressure
B.The number of degrees a refrigerant liquid is below its saturation temperature at the measured liquid pressure
C.The temperature rise of condenser water through the tower
D.The difference between compressor discharge temperature and outdoor dry-bulb temperature
Explanation: Superheat is actual suction-vapor temperature minus saturation temperature at the same pressure, usually taken at the evaporator outlet or compressor inlet. Enough superheat means all liquid has boiled and the compressor is protected from slugging. Typical DX targets are often in the 8 to 15 F range unless the manufacturer specifies otherwise.
5Liquid-line subcooling is best defined as:
A.Suction-vapor temperature minus evaporator saturation temperature
B.The number of degrees liquid refrigerant is below its saturation temperature at the measured liquid pressure
C.Condenser saturation temperature minus outdoor wet-bulb temperature
D.The temperature drop across the expansion valve orifice
Explanation: Subcooling is saturation temperature at liquid-line pressure minus the actual liquid temperature. It confirms that the condenser and receiver are delivering solid liquid to the metering device. Loss of subcooling often means undercharge, high pressure drop, or noncondensables.
6Most of the useful cooling in a direct-expansion evaporator comes from:
A.Sensible heating of superheated vapor after the last droplet boils
B.Sensible cooling of subcooled liquid before it enters the coil
C.Latent heat absorbed as saturated liquid vaporizes at evaporating pressure
D.Heat generated by compressor motor windings
Explanation: The large enthalpy change in the two-phase region is latent heat of vaporization. That is why refrigerants with high latent heat, such as ammonia, move a lot of cooling with relatively little mass flow. Superheat and subcooling add only a small sensible increment compared with boiling.
7For a pure refrigerant, saturation temperature is determined by:
A.The mass of refrigerant in the receiver only
B.The pressure of the two-phase mixture
C.Outdoor dry-bulb temperature alone
D.Compressor motor horsepower
Explanation: On the saturation curve, pressure and temperature are locked together. A pressure-temperature (P-T) chart converts a measured pressure into the boiling or condensing temperature used for superheat and subcooling. Raising evaporating pressure therefore raises coil temperature.
8Ozone depletion potential (ODP) of a refrigerant is associated primarily with:
A.Fluorine content
B.Chlorine or bromine content
C.Molecular weight
D.Critical pressure
Explanation: Chlorine and bromine atoms catalyze stratospheric ozone destruction. CFCs such as R-12 have high ODP and are banned in new equipment; HCFCs such as R-22 have lower ODP and are being phased out. HFCs, HFOs, ammonia, and carbon dioxide contain no chlorine and have zero ODP.
9Flash gas at the expansion device is caused by:
A.The isenthalpic pressure drop that vaporizes part of the liquid to cool the remaining liquid to evaporating temperature
B.Oil logging in the evaporator
C.A dirty condenser coil only
D.Excessive evaporator superheat
Explanation: Throttling is essentially constant enthalpy. When high-pressure liquid drops to evaporator pressure, a fraction must vaporize so the remaining liquid can reach the lower saturation temperature. That flash-gas fraction reduces the liquid available for useful cooling and is why subcooling increases capacity.
10Heat is absorbed from the refrigerated space primarily in the:
A.Condenser
B.Compressor discharge line
C.Evaporator
D.Liquid receiver
Explanation: The evaporator is the low-pressure heat absorber. Refrigerant boils there and takes heat from air, a secondary coolant, or the product. The condenser later rejects that heat plus compressor work to the outdoors.

About the MS Refrigeration Exam

Mississippi Refrigeration Contractor Examination is a classification trade examination administered by PSI for the Mississippi State Board of Contractors. The official open-book exam has 50 questions, a 70% passing standard, and 2 hours allowed. PSI examination fee is $120 per portion (bulletin updated 4/23/2026). This English-language MCQ bank is a study aid for the official content outline; it is not an official PSI form, does not replace the required Law and Business Management exam, and is not a substitute for MSBOC application review or the official open-book examination.

Questions

50 scored questions

Time Limit

2 hours

Passing Score

70%

Exam Fee

$120 (PSI Services LLC (for Mississippi State Board of Contractors))

MS Refrigeration Exam Content Outline

30%

Refrigeration and Refrigerants

Refrigeration cycle and refrigerants

12%

Piping and Tubing

Refrigerant piping

20%

Components

Compressors, evaporators, and condensers

18%

Controls, Valves and Wiring

Controls and refrigerant valves

12%

Tests, Inspections and Maintenance

Testing and maintenance

8%

Safety

Refrigeration safety

How to Pass the MS Refrigeration Exam

What You Need to Know

  • Passing score: 70%
  • Exam length: 50 questions
  • Time limit: 2 hours
  • Exam fee: $120

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

MS Refrigeration Study Tips from Top Performers

1Study only the approved references listed for this classification in the current PSI Mississippi Contractor bulletin (updated 4/23/2026)
2Practice open-book navigation with permanent tabs and indexes before test day
3Drill OSHA 29 CFR 1926 topics that appear across nearly every trade outline
4Confirm MSBOC classification scope and eligibility at msboc.us before scheduling with PSI
5All applicants must also pass Law and Business Management unless it is waived

Frequently Asked Questions

How many questions are on the MS Refrigeration exam?

The official PSI examination has 50 scored questions (plus possible unscored experimental items). Passing is 70% within 2 hours.

How much does the MS Refrigeration exam cost?

PSI lists $120 per examination portion (Candidate Information Bulletin updated 4/23/2026). MSBOC application fees are separate: $400 commercial or $50 residential. Additional classifications are $100 each.

Is the Mississippi contractor exam open book?

Yes. PSI administers MSBOC classification exams as open book. Only bulletin-listed approved references are allowed; temporary tabs such as Post-it notes are prohibited.

Do I still need the Law and Business Management exam?

Yes. MSBOC requires the Mississippi Law and Business Management exam (50 questions, 70%, 2 hours) of all applicants. Reciprocity may waive a trade exam in some cases but does not waive Law and Business.