8-27. During  plant  operation,  which  of  the following symptoms will indicate a clogged  R-12  liquid  line  strainer? 1. The temperature of the tubing on the outlet side of the strainer is much warmer than the tubing on the inlet side 2. The temperature of the tubing on the inlet  side  of  the  strainer  is  much warmer than the tubing on the outlet side 3. The pressure on the outlet side of the strainer tubing is much higher than on the inlet side 4. The pressure on both the inlet and outlet sides of the strainer tubing are the same 8-28.    Which action should you take prior to tightening  the  cap  on  a  liquid  line strainer  that  has  been  cleaned? 1. Test  the  strainer  for  leaks 2. Open the strainer outlet valve 3. Purge  the  air  out  of  the  strainer 4. Replace the strainer screen spring 8-29. Which of the following conditions may be caused by excessive buildup of frost on the  cooling  coils? 1. Low  suction  pressure 2. High  suction  pressure 3. Both 1 and 2 above 4. High  condensing  pressure 8-30. Which  of  the  following  factors  help(s) determine the maximum time between defrosting  of  the  cooling  coils? 1. Amount of refrigerant in the system 2. Moisture content of the supplies 3. Amount of heat to be removed 4. All of the above 8-31. Cooling coils should be defrosted before the  frost  thickness  reaches 1. 1/4  in. 2. 3/16  in. 3. 1/8 in. 4. 5/16  in. 8-32. 8-33. 8-34. 8-35. Questions 8-32 and 8-33 are based on Figure 8-A. Approximately how many inches of mercury represent  the  difference  in  temperature between points B and D? 1. 0.200  in.  absolute 2. 0.232  in.  absolute 3. 0.436  in.  absolute 4. 0.640  in.  absolute Initial  evacuation  of  the  refrigerating system  begins  at  point  A  and  is  completed at point 1. B 2. C 3. D 4. E While you are evacuating and dehydrating a refrigeration system, the vacuum indicator  fails  to  attain  35°F,  which  of the  following  conditions  may  be  the  cause of  this  failure? 1. Lack  of  lubricating  oil  in  the compressor   crankcase 2. Lack of moisture in the system 3. R-12  in  the  lubricating  oil 4. Each  of  the  above  conditions To be properly reactivated, dehydrating agents  should  be  heated  to  (a)  what temperature  and  (b)  for  how  long? 1. (a) 200°F (b) 12 hr 2. (a) 300°F (b) 12 hr 3. (a) 400°F (b) 6 hr 4. (a) 500°F (b) 6 hr 51