3-65. Which of the following factors can cause  a  thermostatic  expansion valve  to  operate  improperly? 1. A collection of dirt on the control  bulb 2.   A collection of Freon at the valve  seat 3. A collection of dirt at the valve  orifice 4. Each of the above 3-66. As a rule, about how many degrees of superheat are picked up by the refrigerant  vapor  before  it  leaves the  cooling  coil? 1. Between 4°F and 12°F 2. Between  15°F  and  20°F 3. Between    30°F   and   38°F 4. Between  45°F  and  50°F 3-67. In  a  refrigerant  plant,  liquid refrigerant may flood back to the compressor  from  the  evaporator  if the  thermostatic  expansion  valve  is in which of the following situations? 1. Stuck  shut 2. Adjusted for too high a degree of superheat at the outlet 3. Adjusted for too low a degree of superheat at the outlet 3-68. If you suspect that the expansion valve  assembly  requires replacement,   which  of  the  following conditions  should  be  met  before making  an  expansion  valve  test? 1. The  liquid  strainers  should  be cleaned 2. The  solenoid  valves  should  be operational 3. The system should be sufficiently  charged 4. All of the above 3-69. A service drum that is used for testing  an  expansion  valve  should contain  which  of  the  following gases? 3-70. You  are  testing  the  thermostatic expansion  valve  of  a  refrigeration plant. When  should  you  immerse  the thermal element in a bath of crushed ice? 1. Before the valve inlet is attached to the gas source 2. After  the  high-pressure  and low-pressure  gauges  have  been connected 3. Before  the  high-pressure  gauge is connected to the valve outlet 4. After the valve on the air supply line has been opened 3-71. A  thermostatic  expansion  valve  is set for 5°F of superheat. What should be the outlet pressure on the gauge? 1. 16.1   psig 2. 22.5   psiq 3. 26.1   psig 4. 32.5   psiq 3-72. Which  of  the  following  operating conditions  is  an  indication  that the expansion valve is seating properly? 1. Pressure  stops  increasing  after a few pounds 2. Pressure  will  build  up  slowly 3. Both 1 and 2 above 4. Pressure  increases  rapidly  and equals  the  inlet  pressure 3-73. You have removed the ice packing from the control bulb. Which of the  following  outlet  pressure conditions  indicates  that  the  valve is  operating  properly? 1. The  pressure  does  not  change 2. The  pressure  decreases  rapidly 3. The  pressure  decreases  a  few pounds  and  then  stabilizes 4. The  pressure  increases  rapidly 1. Pressurized  R-12 2. Wet  compressed  air 3. Oxygen  gas 4. Each of the above 24