NATE CR Service case studies
NATE CR Service · Put your knowledge to work in context.
The NATE Commercial Refrigeration (CR) credential is one of the specialty exams offered within the NATE certification program. NATE describes itself as "the nation's largest nonprofit certification organization for heating, ventilation, air conditioning and refrigeration (HVACR) technicians," and the CR exam is aimed at service technicians who diagnose, maintain, and repair commercial refrigeration systems rather than residential comfort-cooling equipment. Typical candidates work on walk-in coolers and freezers, reach-in display cases, ice machines, rack and remote condensing systems, and the associated controls, defrost, and refrigerant circuits. The exam is intended to validate field competence, not to teach it, so most successful candidates arrive with hands-on commercial experience or a structured training program behind them. The NATE CR Service case studies are 5 cases and about 1,967 words.
1Walk-in Cooler Starved Evaporator with R-448A
A 10 ft × 12 ft walk-in cooler holding produce at 38°F is served by a remote air-cooled condensing unit and a TXV with a 25°F superheat setting. The box has drifted to 46°F over two days.
413 words, about 2 min2Reach-in Freezer Defrost Termination Failure with R-290
A two-door reach-in freezer using R-290 (propane) with a 1/3 hp hermetic compressor and an electric defrost system. The defrost timer initiates every 6 hours for a 30-minute maximum.
397 words, about 2 min3Parallel Rack Oil Return and Floating Head Pressure
A low-temperature parallel rack with three 5 hp semi-hermetic compressors (R-404A) serves six frozen display cases. The rack uses a floating head pressure strategy, with a minimum condensing pressure of 130 psig.
387 words, about 2 min4Remote Air-Cooled Ice Machine Low Production
A remote air-cooled 500 lb/day ice machine (R-404A) produces about 200 lb/day. The machine is rated at 500 lb/day at 70°F air and 50°F water; current conditions are 85°F air and 70°F water.
388 words, about 2 min5Frozen Display Case EEV Superheat Hunting
A frozen food display case with an electronic expansion valve (EEV) and a case controller. The case setpoint is -5°F, but product temperature is 8°F.
382 words, about 2 min