Question

core - question # 23 which of the following is an approved drop - in service replacement for r - 22? a hfc - 134a b r - 407c c r - 407a d there are no direct drop - in refrigerant substitutes

Explanation:

R - 22 is a chlorofluorocarbon (CFC) refrigerant. Due to its ozone - depleting properties, replacements have been sought. However, there are no direct 'drop - in' refrigerant substitutes for R - 22 that can be used without any system modifications. Each potential replacement has different properties such as pressure - temperature relationships, oil compatibility, etc.

Answer:

D. There are no direct 'drop - in' refrigerant substitutes