Question

type i - question # 3
which of the following is a true statement regarding a refrigerant that can be used as a direct service drop - in substitute for r - 22?
a r - 134a used with a tev
b r - 410a used with a tev that has a mop of 75psig.
c r - 290 with a fixed orifice metering device.
d there is no such thing as a drop - in substitute.

Explanation:

R - 22 is a chlorofluorocarbon (CFC) refrigerant. There is no true direct - service 'drop - in' substitute for R - 22 because different refrigerants have different properties such as pressure - temperature relationships, lubrication requirements, and compatibility with system components. While some refrigerants may be used as replacements with system modifications, there is no single refrigerant that can be directly substituted without any changes.

Answer:

D. There is no such thing as a 'drop - in' substitute.