The Idea Behind Crankcase Heaters

  March 12, 2019      Jeff Rosenblum


Why do we see crank case heaters installed? Is it just an extra part to wear out or does it actually help the system?  

Crankcase heaters are there for a reason. They are there to prevent refrigerant from migrating into the oil when it is cold outside. Refrigerant is always drawn to the coldest point when the system goes into the off cycle. This is often the oil in the compressor crank case. The amount of oil migrating depends on the temperature of the compressor.

When the compressor has been off for a while, large amounts of refrigerant can migrate to the compressor and condense. When the compressor starts up, the refrigerant quickly expands and causes the crankcase oil to foam, forcing oil into the system (and out of the compressor). This lack of oil can cause compressor failure due to the lack of lubrication. It will also decrease the efficiency due to having oil in the system that will cause a loss of transfer of heat.

Components, like hard shut off expansion valves and liquid line solenoid valves, can help keep the liquid refrigerant out of the compressor. An oil separator will help to keep the oil in the compressor and out of the system, but the tried and true crankcase heater is a simple strategy to prevent refrigerant in the crankcase. If you find one that has failed, it is a good idea to replace it instead of just cutting it out. It is there for a reason.  

Jeff Rosenblum 
Technical Support
20 Years Industry Experience
Cell (330) 962-2491
[email protected]