92
SERVICE HANDBOOK
Operation
Crankcase Heater Prevents Liquid Migration
This sequence (see Figures 6-6 and 6-7) shows the effects of an electric strap-on crank-
case heater applied to the compressor (also see Figure 6-5). The system was again shut-
down for a weekend under identical conditions with the exception that the heater was
energized throughout the shutdown period. By raising the temperature of the oil, we have
reduced its ability to attract and hold refrigerant.
Note that liquid refrigerant accumulation in the compressor can also be caused by liquid
floodback under certain conditions while operating. This condition can be controlled by
the application of a suction line accumulator. Crankcase heat does nothing to prevent
liquid floodback and an accumulator does nothing to prevent refrigerant migration. Each
without the other is half a job. Both together provide balanced compressor protection.
Compressor
Crankcase
Heater
When applied to a compressor with
a low pressure housing, an electric
strap-on crankcase heater prevents
liquid migration.
FIGURE 6-5:
View through sight glass shows that
the crankcase heater effectively
prevents migration of liquid
refrigerant to the compressor.
FIGURE 6-6:
Normal run with heat. Oil level
is maintained thereby assuring
effective lubrication for compressor
bearings.
FIGURE 6-7:
Summary of Contents for AH5540E
Page 1: ...Hermetic Compressor Service Handbook Wholesale Distribution North America...
Page 2: ......
Page 3: ...Hermetic Compressor Service Handbook Ann Arbor MI 48108 REV 3 11...
Page 4: ......
Page 8: ......
Page 9: ...Chapter 1 General Service Safety Precautions...
Page 16: ......
Page 17: ...Chapter 2 Model and Application...
Page 22: ......
Page 23: ...Chapter 3 Compressor Motor and Component...
Page 36: ......
Page 37: ...Chapter 4 Servicing...
Page 38: ...30 SERVICE HANDBOOK...
Page 79: ...71...
Page 80: ......
Page 81: ...Chapter 5 Installation and Replacement...
Page 96: ......
Page 97: ...Liquid refrigerant migration to compressor FIGURE 6 1 Chapter 6 Operation...
Page 108: ......
Page 109: ...Appendix...
Page 113: ...105 Reciprocating Compressor FIGURE A 2 Internal view of typical air conditioning compressor...
Page 118: ...110 SERVICE HANDBOOK Notes...
Page 119: ......