RETA CIRO REFRIGERANT FLOW
TROUBLESHOOTING PRACTICE EXAM WITH
QUESTIONS AND VERIFIED ANSWERS,
PLUS DETAILED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
1.
An ammonia refrigeration system is operating with a normal condensing
pressure, but the suction pressure at a particular evaporator is
substantially lower than expected. The evaporator has a liquid feed valve
upstream, and the evaporator outlet superheat is considerably higher
than normal. The compressor is otherwise operating normally. Which
condition is the MOST likely explanation?
A. Excessive liquid refrigerant entering the evaporator
B. Restricted refrigerant flow into the evaporator
C. Excessive condenser flooding
D. Excessively low discharge superheat
Answer: B. Restricted refrigerant flow into the evaporator
Rationale: A restriction in the liquid feed path reduces the amount of
refrigerant entering the evaporator. With insufficient refrigerant
available to boil, a larger portion of the evaporator becomes starved,
increasing outlet superheat and lowering the evaporator suction
pressure. Possible causes include a partially closed hand valve,
plugged strainer, malfunctioning control valve, excessive pressure
drop, or an obstructed liquid line.
2.
1
,During troubleshooting of an ammonia evaporator, an operator notices
that the liquid-feed control valve is commanded substantially open, yet
the evaporator continues to operate starved. The pressure differential
available across the valve is adequate. Which observation would provide
the STRONGEST evidence that the problem is actually a restriction
upstream of the control valve?
A. The downstream liquid pressure is significantly lower than the
upstream pressure
B. The compressor discharge temperature is decreasing
C. The condenser pressure is slightly elevated
D. The oil separator level is stable
Answer: A. The downstream liquid pressure is significantly lower
than the upstream pressure
Rationale: A significant pressure drop occurring across an unintended
restriction indicates that the restriction is consuming available
pressure differential. If the pressure is substantially higher
immediately upstream of a suspected restriction and significantly
lower downstream, the operator should investigate strainers, valves,
piping, or other obstructions.
3.
An evaporator is receiving ammonia through a thermostatic expansion
valve. The valve is fully open, but the evaporator outlet superheat
remains extremely high. The liquid receiver contains sufficient
refrigerant, and the liquid-line isolation valves are confirmed open. What
is the most appropriate initial troubleshooting approach?
A. Immediately add ammonia to the system
B. Increase compressor capacity without further investigation
C. Determine whether adequate liquid pressure and subcooling are
2
,reaching the expansion valve
D. Reduce condenser fan capacity
Answer: C. Determine whether adequate liquid pressure and
subcooling are reaching the expansion valve
Rationale: A thermostatic expansion valve requires suitable liquid
supply conditions and adequate pressure differential to feed the
evaporator. Flash gas caused by insufficient liquid pressure or
excessive pressure drop can reduce effective liquid flow through the
valve. Checking liquid pressure, temperature, subcooling, valve inlet
conditions, and pressure drop helps distinguish a supply-side problem
from a valve-control problem.
4.
A liquid-line strainer on an ammonia refrigeration system becomes
partially plugged. Which combination of symptoms would MOST likely
develop?
A. Increased liquid flow and reduced evaporator superheat
B. Reduced pressure drop across the strainer and higher evaporator
capacity
C. Increased pressure drop across the strainer and reduced refrigerant
flow downstream
D. Increased suction pressure and increased evaporator flooding
Answer: C. Increased pressure drop across the strainer and reduced
refrigerant flow downstream
Rationale: A plugged strainer increases resistance to refrigerant flow.
As the restriction becomes more severe, pressure falls across the
strainer and less liquid reaches downstream components. The
resulting evaporator starvation commonly produces higher superheat
and reduced cooling capacity.
3
, 5.
An ammonia evaporator shows a large difference in temperature
between the inlet region and the outlet region. The outlet temperature is
significantly warmer than expected, and the evaporator has high
superheat. What does this pattern MOST strongly indicate?
A. The evaporator is adequately flooded
B. The evaporator is starved of refrigerant
C. The condenser is overfilled with liquid
D. The compressor is receiving excessive liquid
Answer: B. The evaporator is starved of refrigerant
Rationale: A starved evaporator has insufficient liquid refrigerant
available to boil throughout the heat-transfer surface. Once the
available liquid has evaporated, the remaining portion of the
evaporator and suction line contains superheated vapor, causing the
outlet temperature to rise and increasing measured superheat.
6.
A high-pressure receiver is supplying liquid ammonia to several
evaporators. One evaporator suddenly loses capacity while the others
continue operating normally. Which troubleshooting observation would
BEST help determine whether the problem is local to that evaporator's
liquid feed circuit?
A. Compare its liquid-feed pressure and temperature with those of a
normally operating evaporator
B. Increase system suction pressure immediately
C. Shut down every compressor
D. Raise the condenser pressure
4
TROUBLESHOOTING PRACTICE EXAM WITH
QUESTIONS AND VERIFIED ANSWERS,
PLUS DETAILED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
1.
An ammonia refrigeration system is operating with a normal condensing
pressure, but the suction pressure at a particular evaporator is
substantially lower than expected. The evaporator has a liquid feed valve
upstream, and the evaporator outlet superheat is considerably higher
than normal. The compressor is otherwise operating normally. Which
condition is the MOST likely explanation?
A. Excessive liquid refrigerant entering the evaporator
B. Restricted refrigerant flow into the evaporator
C. Excessive condenser flooding
D. Excessively low discharge superheat
Answer: B. Restricted refrigerant flow into the evaporator
Rationale: A restriction in the liquid feed path reduces the amount of
refrigerant entering the evaporator. With insufficient refrigerant
available to boil, a larger portion of the evaporator becomes starved,
increasing outlet superheat and lowering the evaporator suction
pressure. Possible causes include a partially closed hand valve,
plugged strainer, malfunctioning control valve, excessive pressure
drop, or an obstructed liquid line.
2.
1
,During troubleshooting of an ammonia evaporator, an operator notices
that the liquid-feed control valve is commanded substantially open, yet
the evaporator continues to operate starved. The pressure differential
available across the valve is adequate. Which observation would provide
the STRONGEST evidence that the problem is actually a restriction
upstream of the control valve?
A. The downstream liquid pressure is significantly lower than the
upstream pressure
B. The compressor discharge temperature is decreasing
C. The condenser pressure is slightly elevated
D. The oil separator level is stable
Answer: A. The downstream liquid pressure is significantly lower
than the upstream pressure
Rationale: A significant pressure drop occurring across an unintended
restriction indicates that the restriction is consuming available
pressure differential. If the pressure is substantially higher
immediately upstream of a suspected restriction and significantly
lower downstream, the operator should investigate strainers, valves,
piping, or other obstructions.
3.
An evaporator is receiving ammonia through a thermostatic expansion
valve. The valve is fully open, but the evaporator outlet superheat
remains extremely high. The liquid receiver contains sufficient
refrigerant, and the liquid-line isolation valves are confirmed open. What
is the most appropriate initial troubleshooting approach?
A. Immediately add ammonia to the system
B. Increase compressor capacity without further investigation
C. Determine whether adequate liquid pressure and subcooling are
2
,reaching the expansion valve
D. Reduce condenser fan capacity
Answer: C. Determine whether adequate liquid pressure and
subcooling are reaching the expansion valve
Rationale: A thermostatic expansion valve requires suitable liquid
supply conditions and adequate pressure differential to feed the
evaporator. Flash gas caused by insufficient liquid pressure or
excessive pressure drop can reduce effective liquid flow through the
valve. Checking liquid pressure, temperature, subcooling, valve inlet
conditions, and pressure drop helps distinguish a supply-side problem
from a valve-control problem.
4.
A liquid-line strainer on an ammonia refrigeration system becomes
partially plugged. Which combination of symptoms would MOST likely
develop?
A. Increased liquid flow and reduced evaporator superheat
B. Reduced pressure drop across the strainer and higher evaporator
capacity
C. Increased pressure drop across the strainer and reduced refrigerant
flow downstream
D. Increased suction pressure and increased evaporator flooding
Answer: C. Increased pressure drop across the strainer and reduced
refrigerant flow downstream
Rationale: A plugged strainer increases resistance to refrigerant flow.
As the restriction becomes more severe, pressure falls across the
strainer and less liquid reaches downstream components. The
resulting evaporator starvation commonly produces higher superheat
and reduced cooling capacity.
3
, 5.
An ammonia evaporator shows a large difference in temperature
between the inlet region and the outlet region. The outlet temperature is
significantly warmer than expected, and the evaporator has high
superheat. What does this pattern MOST strongly indicate?
A. The evaporator is adequately flooded
B. The evaporator is starved of refrigerant
C. The condenser is overfilled with liquid
D. The compressor is receiving excessive liquid
Answer: B. The evaporator is starved of refrigerant
Rationale: A starved evaporator has insufficient liquid refrigerant
available to boil throughout the heat-transfer surface. Once the
available liquid has evaporated, the remaining portion of the
evaporator and suction line contains superheated vapor, causing the
outlet temperature to rise and increasing measured superheat.
6.
A high-pressure receiver is supplying liquid ammonia to several
evaporators. One evaporator suddenly loses capacity while the others
continue operating normally. Which troubleshooting observation would
BEST help determine whether the problem is local to that evaporator's
liquid feed circuit?
A. Compare its liquid-feed pressure and temperature with those of a
normally operating evaporator
B. Increase system suction pressure immediately
C. Shut down every compressor
D. Raise the condenser pressure
4
