RETA CIRO OIL-RELATED COMPRESSOR
TROUBLESHOOTING PRACTICE EXAM WITH
ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A reciprocating ammonia compressor shows a gradual increase in oil
pressure differential across the oil filter. Discharge pressure and suction
pressure remain relatively stable, but the oil-pressure differential
continues to rise. Which condition is the MOST likely explanation?
A. Excessive refrigerant superheat
B. Progressive oil-filter loading
C. Low condenser water temperature
D. Excessive compressor clearance volume
Answer: B. Progressive oil-filter loading
Rationale: A rising pressure differential across an oil filter is a classic
indication that the filter is becoming restricted by contaminants,
sludge, degraded oil, or other debris. The restriction increases the
pressure drop required to move oil through the element. If ignored, the
compressor may eventually experience inadequate lubrication. The
technician should compare the differential against the manufacturer's
allowable limit and investigate the source of contamination rather
than merely replacing the element repeatedly.
2. During troubleshooting, a CIRO observes that compressor oil pressure
is abnormally low even though the oil level in the crankcase appears
1
,adequate. The oil filter differential pressure is normal. Which additional
condition should be investigated FIRST?
A. Excessively high oil viscosity
B. Restricted suction gas flow
C. Excessive wear or internal leakage in the oil pump
D. Excessive condenser subcooling
Answer: C. Excessive wear or internal leakage in the oil pump
Rationale: An adequate oil level and a normal filter differential
eliminate two common causes of low oil pressure. If the pump cannot
develop sufficient pressure because of worn gears, damaged
components, excessive internal clearances, or bypass-valve problems,
measured oil pressure can fall despite having sufficient oil available.
The technician should verify pressure with an accurate instrument
and compare readings at appropriate points in the oil circuit before
concluding that the pump itself has failed.
3. A compressor repeatedly trips on low oil differential pressure shortly
after startup. The oil temperature is substantially lower than normal.
What is the MOST likely contributing factor?
A. Oil viscosity is excessively high at startup
B. Compressor discharge temperature is too low
C. Refrigerant condenser pressure is excessive
D. The oil separator is operating too efficiently
Answer: A. Oil viscosity is excessively high at startup
Rationale: Cold oil becomes more viscous and can move more slowly
through small passages, filters, bearings, and control devices. During
startup, this can produce abnormal oil-pressure relationships and
delay proper oil circulation. The correct response is not simply to
defeat the oil-pressure safety control; the technician should determine
2
,why the oil is too cold, verify the oil-heating strategy, and ensure that
the compressor is being started under the manufacturer's specified
conditions.
4. A screw compressor's oil temperature is consistently higher than its
normal operating range. Which condition could directly contribute to
this problem?
A. Excessive oil cooling
B. Insufficient oil cooling
C. Excessively clean oil
D. Low bearing load
Answer: B. Insufficient oil cooling
Rationale: Screw compressors depend on oil for lubrication, sealing,
and often significant heat removal. If the oil cooler is fouled, cooling-
water flow is inadequate, refrigerant cooling is insufficient, or a
temperature-control device is malfunctioning, oil temperature can rise.
Excessively hot oil can lose desirable viscosity, accelerate oxidation,
reduce film strength, and increase wear. The technician should
determine whether the problem originates in the oil circuit, cooler,
cooling medium, or control system.
5. An ammonia compressor's oil analysis shows unusually high metal
content. What does this finding MOST strongly suggest?
A. Improved bearing lubrication
B. Mechanical wear occurring somewhere in the lubricated system
C. Excessive refrigerant purity
D. A properly functioning oil separator
Answer: B. Mechanical wear occurring somewhere in the lubricated
system
3
, Rationale: Elevated metals in oil can indicate wear of bearings, gears,
shafts, bushings, or other lubricated components. The specific metal
type can help identify the source. Oil analysis should therefore be
interpreted together with vibration, temperature, pressure, inspection,
and operating-history information. Continuing to operate a machine
with rapidly increasing wear-metal concentrations can turn a
developing mechanical problem into a catastrophic failure.
6. A technician discovers that compressor oil is becoming unusually
dark and has a burnt odor. Which condition should receive immediate
attention?
A. Excessively low compressor loading
B. Oil overheating or thermal degradation
C. Excessive oil filtration efficiency
D. Low ambient temperature
Answer: B. Oil overheating or thermal degradation
Rationale: Darkened oil and a burnt odor can be evidence of excessive
temperature, oxidation, contamination, or chemical degradation.
Overheated oil may lose lubricating properties and generate deposits
that interfere with valves, bearings, filters, and oil passages. The
technician should investigate oil temperature, cooling performance,
compressor discharge conditions, and possible electrical or
mechanical problems instead of simply replacing the oil without
identifying the cause.
7. A compressor has adequate oil pressure at the pump outlet but
inadequate oil pressure at the bearings. What is the MOST logical
troubleshooting direction?
4
TROUBLESHOOTING PRACTICE EXAM WITH
ACTUAL QUESTIONS AND VERIFIED
ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A reciprocating ammonia compressor shows a gradual increase in oil
pressure differential across the oil filter. Discharge pressure and suction
pressure remain relatively stable, but the oil-pressure differential
continues to rise. Which condition is the MOST likely explanation?
A. Excessive refrigerant superheat
B. Progressive oil-filter loading
C. Low condenser water temperature
D. Excessive compressor clearance volume
Answer: B. Progressive oil-filter loading
Rationale: A rising pressure differential across an oil filter is a classic
indication that the filter is becoming restricted by contaminants,
sludge, degraded oil, or other debris. The restriction increases the
pressure drop required to move oil through the element. If ignored, the
compressor may eventually experience inadequate lubrication. The
technician should compare the differential against the manufacturer's
allowable limit and investigate the source of contamination rather
than merely replacing the element repeatedly.
2. During troubleshooting, a CIRO observes that compressor oil pressure
is abnormally low even though the oil level in the crankcase appears
1
,adequate. The oil filter differential pressure is normal. Which additional
condition should be investigated FIRST?
A. Excessively high oil viscosity
B. Restricted suction gas flow
C. Excessive wear or internal leakage in the oil pump
D. Excessive condenser subcooling
Answer: C. Excessive wear or internal leakage in the oil pump
Rationale: An adequate oil level and a normal filter differential
eliminate two common causes of low oil pressure. If the pump cannot
develop sufficient pressure because of worn gears, damaged
components, excessive internal clearances, or bypass-valve problems,
measured oil pressure can fall despite having sufficient oil available.
The technician should verify pressure with an accurate instrument
and compare readings at appropriate points in the oil circuit before
concluding that the pump itself has failed.
3. A compressor repeatedly trips on low oil differential pressure shortly
after startup. The oil temperature is substantially lower than normal.
What is the MOST likely contributing factor?
A. Oil viscosity is excessively high at startup
B. Compressor discharge temperature is too low
C. Refrigerant condenser pressure is excessive
D. The oil separator is operating too efficiently
Answer: A. Oil viscosity is excessively high at startup
Rationale: Cold oil becomes more viscous and can move more slowly
through small passages, filters, bearings, and control devices. During
startup, this can produce abnormal oil-pressure relationships and
delay proper oil circulation. The correct response is not simply to
defeat the oil-pressure safety control; the technician should determine
2
,why the oil is too cold, verify the oil-heating strategy, and ensure that
the compressor is being started under the manufacturer's specified
conditions.
4. A screw compressor's oil temperature is consistently higher than its
normal operating range. Which condition could directly contribute to
this problem?
A. Excessive oil cooling
B. Insufficient oil cooling
C. Excessively clean oil
D. Low bearing load
Answer: B. Insufficient oil cooling
Rationale: Screw compressors depend on oil for lubrication, sealing,
and often significant heat removal. If the oil cooler is fouled, cooling-
water flow is inadequate, refrigerant cooling is insufficient, or a
temperature-control device is malfunctioning, oil temperature can rise.
Excessively hot oil can lose desirable viscosity, accelerate oxidation,
reduce film strength, and increase wear. The technician should
determine whether the problem originates in the oil circuit, cooler,
cooling medium, or control system.
5. An ammonia compressor's oil analysis shows unusually high metal
content. What does this finding MOST strongly suggest?
A. Improved bearing lubrication
B. Mechanical wear occurring somewhere in the lubricated system
C. Excessive refrigerant purity
D. A properly functioning oil separator
Answer: B. Mechanical wear occurring somewhere in the lubricated
system
3
, Rationale: Elevated metals in oil can indicate wear of bearings, gears,
shafts, bushings, or other lubricated components. The specific metal
type can help identify the source. Oil analysis should therefore be
interpreted together with vibration, temperature, pressure, inspection,
and operating-history information. Continuing to operate a machine
with rapidly increasing wear-metal concentrations can turn a
developing mechanical problem into a catastrophic failure.
6. A technician discovers that compressor oil is becoming unusually
dark and has a burnt odor. Which condition should receive immediate
attention?
A. Excessively low compressor loading
B. Oil overheating or thermal degradation
C. Excessive oil filtration efficiency
D. Low ambient temperature
Answer: B. Oil overheating or thermal degradation
Rationale: Darkened oil and a burnt odor can be evidence of excessive
temperature, oxidation, contamination, or chemical degradation.
Overheated oil may lose lubricating properties and generate deposits
that interfere with valves, bearings, filters, and oil passages. The
technician should investigate oil temperature, cooling performance,
compressor discharge conditions, and possible electrical or
mechanical problems instead of simply replacing the oil without
identifying the cause.
7. A compressor has adequate oil pressure at the pump outlet but
inadequate oil pressure at the bearings. What is the MOST logical
troubleshooting direction?
4
