high-pressure cutout switch is jammed open
low-pressure switch is jammed shut
thermal bulb is not operating properly
scale trap is clogged
第1题：
If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably _____.
A.misalignment or worn main bearings
B.insufficient cylinder lubrication
C.defective or poorly fitted valves
D.All of the above
第2题：
If the suction pressure for an operating refrigeration compressor is below normal, the cause may be ______.
A.an excess of liquid refrigerant
B.the expansion valve overfeeding
C.a fouled compressor suction strainer
D.the compressor short cycling
第3题：
A.Your attention please! Please add-value at the Custermer Sercice Center as the Value Machines are not working. We apologize for any inconvenience this might cause.
B.Your attention please! Please buy ticket at the Custermer Sercice Center as the ticket machines are not working. We apologize for any inconvenience this might cause.
C.Your attention please! Please follow staff directions to enter as the entry gates are not working. We apologize for any inconvenience this might cause.
D.Your attention please! Station lighting is under emergency repair but trains are still running. Please contact staff if you need any assistance. We apologize for any inconvenience this might cause.
第4题：
Closing of the solenoid valve
Closing of the expansion valve
An increase in the suction pressure
Decreasing the suction pressure
第5题：
What is the most probable cause of reduced capacity in a reciprocating air compressor ________．
A.Carbon on cylinder heads
B.Faulty unloader
C.Leaking air valves
D.Plugged air cooler
第6题：
Badly leaking refrigeration compressor discharge valves will cause ______.
A.overfeeding of the expansion valve
B.damage to the condenser
C.constant running of the compressor
D.flooding of the receiver
第7题：
Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause______.
A.carbon deposits on the compressor suction valves
B.the evaporator temperature to increase
C.rapid corrosion of the thermal expansion valve
D.no operating problems
第8题：
If the refrigeration compressor crankcase is sweating, the cause may be due to
A.a shortage of refrigerant
B.the compressor running continuously
C.liquid refrigerant returning to the compressor
D.the compressor short cycling on the high pressure cutout
第9题：
Shortage of refrigerant oil
Slight shortage of refrigerant
Excessive condenser cooling water flow
Faulty expansion valve
第10题：
system was overcharged with refrigerant
high pressure switch was improperly adjusted
expansion valve strainers were fouled
suction valves were leaking slightly