What happens to the pressures within the system during hot gas defrost?

During hot gas defrost, the system is initiated to remove ice or frost buildup from the evaporator coils by reversing the flow of refrigerant. This process involves routing hot refrigerant gas from the compressor directly to the evaporator.

When the hot refrigerant enters the evaporator, it absorbs heat, which causes the frost to melt. As a result, the temperature rises, and consequently, the pressure within the evaporator increases since the gas expands and fills the evaporator's volume. This increased pressure aids in promoting the defrosting process by allowing the heat energy from the gas to effectively transfer and melt the ice.

In contrast, the other choices offered do not accurately reflect what occurs during hot gas defrost. For instance, the pressure in the compressor typically increases as well, as it is sending high-pressure gas into the evaporator. Pressure generally does not remain constant in the system during this process, and while the condenser may experience changes in pressure due to altered flow of refrigerant, it is not the primary focus during defrost cycles.