8-8. What method should you use to remove 8-13.    A refrigeration unit is working under a foreign deposits from the tubes of a normal  heat  load  and  has  a  sufficient refrigerant   condenser? charge of refrigerant. The water side of the  condenser  should  be  cleaned  if  the 1. Lance  with  water  only operating  difference  between  the 2. Lance  with  air  only temperature  corresponding  to  the 3. Both 1 and 2 above condensing  pressure  and  the  temperature 4. Wash  with  acid  solution of  the  outlet  circulating  water  increases above the temperature obtained when the 8-9. On an air-cooled condenser, the exterior unit was in good condition by how many surfaces of the tubes and fins are dirty degrees? and restricting air circulation. What should  be  used  to  clean  these  surfaces? 1. 5°F to 10°F 2. 10°F to 20°F 1. Jets  of  steam 3. 20°F to 30°F 2. Hot  water  lances 4. 30°F to 40°F 3. Compressed  air  lances 4. Stiff  bristled  brushes 8-14.    How does the temperature at the outlet side  of  the  valve  compare  with  the 8-10. How often should the water side of a temperature  at  the  inlet  side  when  the condenser in a freon system be tested for thermostatic  valve  is  operating  properly? refrigerant   leakage? 1. Daily 2. Weekly 3. Bi-weekly 4. Monthly 8-11. You are testing condenser tubes for leakage. Why do you hold the exploring tube of the leak detector at one end of each condenser tube for about 10 seconds before driving a cork into each end of 8-15. the tube? 1. To dry the tube heads 2. To detect the presence of R-12 3. To draw fresh air through the tube 4. To vaporize any water left in the tube 8-12. You are attempting to locate leaks in a refrigerator   condenser. For  what  period of time should the condenser be allowed to remain idle after all tubes in the 8-16. suspected  section  have  been  corked, before  continuing  the  test? 1. 2  to 4  hr 2. 4  to 6  hr 3. 6  to 8  hr 4. 8 to   10 hr 1. The temperature is lower at the outlet  side 2. The temperature is lower at the inlet side 3. The  temperature  is  approximately  the same at the outlet and the inlet sides 4. The  temperature  is  higher  at  the inlet side 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  factors 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 Question 8-17 is to be judged True or False. 8-17. If  you  increase  the  spring  pressure  of the  thermostatic  expansion  valve  to  give a  high  degree  of  superheat  at  the evaporator coil outlet, you may cause a low  lube  oil  level  in  the  compressor crankcase. 49