FDNY Z-51 RMO Certification
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1.
A refrigeration plant operator notices the compressor is running continuously but
the chilled water supply temperature is not reaching setpoint. What is the most
likely cause?
A. Excess heat load or undersized system capacity
B. Overcharged refrigerant system
C. Oversized condenser fan
D. Low ambient temperature
Answer: A
Rationale: Continuous compressor operation with poor cooling indicates the
system cannot meet demand.
2.
A system shows fluctuating suction pressure during steady load operation. What
is the most likely cause?
A. Expansion valve hunting or instability
B. Stable refrigerant flow
C. Oversized evaporator
D. Clean condenser coils
,Answer: A
Rationale: Hunting occurs when the expansion valve overcorrects flow.
3.
A compressor trips on overload protection shortly after startup. What is the most
likely cause?
A. High head pressure or mechanical binding
B. Low ambient temperature
C. Clean suction line
D. Proper lubrication
Answer: A
Rationale: Overload is commonly caused by excessive compression load.
4.
A refrigeration system shows oil stains around shaft seals. What is the most likely
issue?
A. Seal failure or excessive internal pressure
B. Clean system operation
C. High evaporator efficiency
D. Proper lubrication
Answer: A
Rationale: Oil leakage indicates seal degradation.
5.
A chilled water system has normal pressure but reduced cooling output. What is
the most likely cause?
A. Fouled heat exchanger surfaces
B. High refrigerant charge
,C. Clean evaporator
D. Proper airflow
Answer: A
Rationale: Fouling reduces heat transfer efficiency.
6.
A supervisor observes compressor discharge temperature is unusually high. What
is the first system check?
A. Suction pressure and superheat
B. Fan blade condition
C. Room humidity
D. Pipe insulation thickness
Answer: A
Rationale: Low suction pressure increases compression heat.
7.
A refrigeration system shows bubbles in the liquid line sight glass. What does this
indicate?
A. Low refrigerant charge
B. Overcharged system
C. Normal operation
D. Excess subcooling
Answer: A
Rationale: Vapor presence indicates insufficient liquid refrigerant.
8.
A system shows evaporator icing while compressor runs continuously. What is the
likely cause?
, A. Restricted airflow across evaporator
B. High ambient temperature
C. Oversized compressor
D. Proper defrost cycle
Answer: A
Rationale: Lack of airflow causes freezing.
9.
A refrigeration compressor produces knocking sounds during startup. What is
most likely cause?
A. Liquid refrigerant entering compressor
B. High suction superheat
C. Clean oil system
D. Stable system operation
Answer: A
Rationale: Liquid slugging causes mechanical damage.
10.
A system trips on high-pressure safety repeatedly during daytime operation.
What is most likely cause?
A. Condenser airflow restriction
B. Low refrigerant charge
C. Clean evaporator
D. Proper system balance
Answer: A
Rationale: Poor heat rejection increases pressure.
11.
Examination Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1.
A refrigeration plant operator notices the compressor is running continuously but
the chilled water supply temperature is not reaching setpoint. What is the most
likely cause?
A. Excess heat load or undersized system capacity
B. Overcharged refrigerant system
C. Oversized condenser fan
D. Low ambient temperature
Answer: A
Rationale: Continuous compressor operation with poor cooling indicates the
system cannot meet demand.
2.
A system shows fluctuating suction pressure during steady load operation. What
is the most likely cause?
A. Expansion valve hunting or instability
B. Stable refrigerant flow
C. Oversized evaporator
D. Clean condenser coils
,Answer: A
Rationale: Hunting occurs when the expansion valve overcorrects flow.
3.
A compressor trips on overload protection shortly after startup. What is the most
likely cause?
A. High head pressure or mechanical binding
B. Low ambient temperature
C. Clean suction line
D. Proper lubrication
Answer: A
Rationale: Overload is commonly caused by excessive compression load.
4.
A refrigeration system shows oil stains around shaft seals. What is the most likely
issue?
A. Seal failure or excessive internal pressure
B. Clean system operation
C. High evaporator efficiency
D. Proper lubrication
Answer: A
Rationale: Oil leakage indicates seal degradation.
5.
A chilled water system has normal pressure but reduced cooling output. What is
the most likely cause?
A. Fouled heat exchanger surfaces
B. High refrigerant charge
,C. Clean evaporator
D. Proper airflow
Answer: A
Rationale: Fouling reduces heat transfer efficiency.
6.
A supervisor observes compressor discharge temperature is unusually high. What
is the first system check?
A. Suction pressure and superheat
B. Fan blade condition
C. Room humidity
D. Pipe insulation thickness
Answer: A
Rationale: Low suction pressure increases compression heat.
7.
A refrigeration system shows bubbles in the liquid line sight glass. What does this
indicate?
A. Low refrigerant charge
B. Overcharged system
C. Normal operation
D. Excess subcooling
Answer: A
Rationale: Vapor presence indicates insufficient liquid refrigerant.
8.
A system shows evaporator icing while compressor runs continuously. What is the
likely cause?
, A. Restricted airflow across evaporator
B. High ambient temperature
C. Oversized compressor
D. Proper defrost cycle
Answer: A
Rationale: Lack of airflow causes freezing.
9.
A refrigeration compressor produces knocking sounds during startup. What is
most likely cause?
A. Liquid refrigerant entering compressor
B. High suction superheat
C. Clean oil system
D. Stable system operation
Answer: A
Rationale: Liquid slugging causes mechanical damage.
10.
A system trips on high-pressure safety repeatedly during daytime operation.
What is most likely cause?
A. Condenser airflow restriction
B. Low refrigerant charge
C. Clean evaporator
D. Proper system balance
Answer: A
Rationale: Poor heat rejection increases pressure.
11.
