when recovering cfc, hcfc, or hfc refrigerant into a non-pressurized container from a household refrigerator with an inoperative compressor it is; a. helpful to heat and strike the compressor with a rubber mallet. b. only necessary to recover as much refrigerant as will naturally flow out of the system. c. not necessary to recover since the refrigerant is probably contaminated. d. necessary to chase refrigerant from the oil with pressurized dry nitrogen.