CRST Cheat Sheet 2026

The 30 highest-yield CRST facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What does a high-pressure control (HPC) do in a refrigeration system? → Shuts down the compressor when discharge pressure exceeds the set point
2. What minimum refrigerant velocity is generally required in vertical suction line risers to ensure adequate oil return to the compressor? → 700-1,000 fpm
3. How does root cause analysis improve repair effectiveness? → Identify underlying problems
4. In a refrigeration ladder diagram, what symbol represents a normally open (NO) contact? → Two parallel vertical lines with a gap between horizontal lines
5. When a CRST professional encounters an unexpected result during a procedure, the FIRST action should be to: → Stop, assess the situation, and determine whether to proceed or seek guidance
6. What type of capacitor provides an extra boost of starting torque for a PSC or CSCR compressor motor? → Start capacitor
7. What is the PRIMARY purpose of obtaining CRST certification in Certified Refrigeration Service Technician? → To demonstrate verified competency and adherence to professional standards
8. What is the PRIMARY purpose of obtaining CRST certification in Certified Refrigeration Service Technician? → To demonstrate verified competency and adherence to professional standards
9. In what direction should horizontal suction lines be sloped to promote oil return? → 1/4 inch per foot sloping toward the compressor
10. What is the standard voltage for a single-phase residential refrigeration compressor in the US? → 115V or 230V
11. Which refrigerant has an Ozone Depletion Potential (ODP) of zero and is commonly used in new commercial refrigeration systems in the US? → R-404A
12. What role does proper diagnosis play in repairs? → Correctly identify issues
13. What refrigerant is classified as R-717 and widely used in large industrial refrigeration systems? → Ammonia (NH3)
14. Which statement BEST describes the relationship between Certified Refrigeration Service Technician certification and industry evolution? → Requirements evolve periodically to reflect advances in knowledge and practice
15. When a long horizontal suction line transitions into a vertical riser, what piping configuration is recommended at the base of the riser? → Install a P-trap (inverted trap) to accumulate and batch-transport oil up the riser
16. What thermodynamic process occurs in the evaporator of a vapor-compression refrigeration cycle? → Refrigerant absorbs heat from the load and vaporizes at constant pressure
17. In Certified Refrigeration Service Technician practice, what is the FIRST step when a safety hazard is identified in the workplace? → Immediately secure the area and report the hazard
18. Which factor MOST significantly affects the quality of technical outcomes in CRST practice? → The practitioner's training, preparation, and attention to detail
19. How does the sight glass help in system maintenance? → Observe refrigerant flow
20. What environmental regulations affect refrigerant handling? → Prevent ozone depletion
21. What is the primary purpose of flowing dry nitrogen through refrigeration piping during the brazing process? → To prevent internal oxidation and copper oxide scale formation inside the tubing
22. Which approach is MOST important for CRST professionals when applying technical procedures? → Adhering to established protocols while adapting to specific conditions
23. At approximately what temperature range does silver-phosphorus-copper (BCuP-5) brazing alloy flow and fill refrigeration copper joints? → 1,200–1,500°F (649–816°C)
24. In Certified Refrigeration Service Technician practice, what is the CORRECT sequence when performing a technical procedure? → Plan, prepare, execute, verify, and document
25. How does the CRST body of knowledge relate to daily professional practice? → It provides the foundational framework guiding decision-making and standard practices
26. In a refrigeration control circuit, what is the primary function of a thermostat? → Cycle the compressor on and off to maintain set temperature
27. Why is refrigerant recovery required? → Capture and reuse
28. When a CRST professional encounters an unexpected result during a procedure, the FIRST action should be to: → Stop, assess the situation, and determine whether to proceed or seek guidance
29. What is the boiling point of R-134a at atmospheric pressure (14.7 psia)? → -15.07°F (-26.15°C)
30. What is the MOST important reason for maintaining equipment maintenance logs in CRST practice? → To track maintenance history, predict failures, and demonstrate compliance