A vent is included into a scroll compressor for protecting a refrigerant
system in the event of loss of charge. The vent selectively taps an
entrapped compression chamber to a housing chamber which surrounds the
motor. In the event of a low charge, the gas in the compression chamber
will be at a high temperature, and will heat the motor when the vent
opens. The vented heated gas will then actuate a temperature protection
device on the motor, causing the motor to stop rotation. In further
embodiments, the compression chamber which supplies the tapped fluid is
the discharge port.