Understanding the Defrost Cycle in Reverse Cycle Refrigerated Systems

Reverse cycle refrigerated systems, when in heating mode, go through a defrost cycle. This cycle is managed by the outdoor unit and is triggered by the outdoor weather conditions, including temperature and humidity. It's a normal part of the system's operation and cannot be prevented.

What is the Defrost Cycle?

The defrost cycle happens when the outdoor unit detects ice building up on its coil. This is monitored by two sensors: the outdoor coil sensor and the outdoor air sensor. When these sensors detect ice, the system temporarily switches from heating to cooling (though the indoor fan is turned off). This reversal sends hot refrigerant to the outdoor unit to melt the ice. During this process, you might see water discharging from the outdoor unit; this is normal.

The defrost cycle will stop when either the outdoor coil temperature reaches 5°C or after running for a maximum of 20 minutes. Once the defrost cycle ends, the system automatically switches back to heating mode.

Tip to Minimize Defrost Cycles

While you can't prevent the defrost cycle, you can reduce how often it occurs. Try to keep the set temperature and the actual room temperature close together (within 5-6°C). This helps prevent the compressor from working too hard, which can reduce the frequency of defrost cycles.