18. when service equipment hoses with manual shutoff valves are not connected to an a/c system, the valves…

18. when service equipment hoses with manual shutoff valves are not connected to an a/c system, the valves should be in the:\n(a) mid - seated position.\n(b) back - seated position.\n(c) closed position.\n(d) open position.\n19. technician a says that r - 1234yf may be used to retrofit an r - 134a system.\ntechnician b says that r - 1234yf is an ozone - depleting gas.\nwho is right?\n(a) a only\n(b) b only\n(c) both a and b\n(d) neither a nor b

18. when service equipment hoses with manual shutoff valves are not connected to an a/c system, the valves should be in the:\n(a) mid - seated position.\n(b) back - seated position.\n(c) closed position.\n(d) open position.\n19. technician a says that r - 1234yf may be used to retrofit an r - 134a system.\ntechnician b says that r - 1234yf is an ozone - depleting gas.\nwho is right?\n(a) a only\n(b) b only\n(c) both a and b\n(d) neither a nor b

Answer

Brief Explanations:

  1. For question 18, when service - equipment hoses with manual shutoff valves are not connected to an A/C system, to prevent leakage and ensure safety, the valves should be in the back - seated position. This position provides a more secure seal compared to other options.
  2. For question 19, R - 1234yf cannot be used to retrofit an R - 134a system without proper modifications as they have different properties. Also, R - 1234yf is not an ozone - depleting gas. So neither technician A nor technician B is correct.

Answer:

  1. B. back - seated position
  2. D. Neither A nor B