When does a time initiated, pressure-terminated defrost timer turn off defrost?

A time-initiated, pressure-terminated defrost timer turns off defrost when the evaporator pressure corresponds to the temperature at which the ice would have melted. This is essential because the primary goal of the defrost cycle is to remove any accumulated frost or ice from the evaporator coil, which can hinder the efficiency of the system.

During the defrost cycle, the system operates under the assumption that pressure changes correspond directly to temperatures in the evaporator coil. As the frost melts and the coil temperature rises, the pressure within the system increases. Once the evaporator pressure indicates that the ice has melted — corresponding to a specific temperature — the defrost timer concludes that it can safely terminate the defrost cycle. This ensures that the system operates efficiently and resumes normal heating operation without any ice build-up that could degrade performance.

The other choices focus on different aspects of system operation and do not accurately capture the specific mechanism of the pressure termination feature in defrost systems.