Outdoor Unit Menu / 13.6 – Defrost Trigger

The outdoor unit of the air conditioner uses its own algorithm to initiate the defrost process. Under certain conditions, however, situations may occur where it would be beneficial to start defrosting earlier than the outdoor unit decides. This is because the outdoor unit is controlled not only by temperatures but also by time. This internal timer does not allow defrosting to start earlier than approximately 45–50 minutes of compressor operation.

Under unfavorable outdoor conditions and at high compressor output, it may happen that the outdoor unit heat exchanger freezes sooner, in some cases as early as 20–30 minutes after the last defrost cycle. This negatively affects the efficiency of the entire system, and it is often more advantageous to initiate defrosting more frequently.

The Defrost Trigger function makes this possible based on configured conditions. However, this function does not disable the outdoor unit’s internal algorithm, so the outdoor unit will still initiate defrosting according to its own rules (for example, after a long compressor runtime without defrosting at low outdoor temperatures).

Minimum Time

– Specifies the minimum compressor runtime after which defrosting is allowed, provided that the Delta T condition is met.

Delta T (Outdoor – Evaporating Temperature)

– Specifies the temperature difference between the outdoor temperature and the evaporating temperature at which defrosting will be initiated.

Maximum TIME under TEMPERATURE

– Sets the maximum time the compressor is allowed to run without defrosting when the outdoor temperature is below the configured value. Older air conditioner models in PID mode tend to defrost very reluctantly, and this setting limits the maximum time without defrosting at low outdoor temperatures. In addition, some air conditioners do not report temperatures lower than −20 °C to MiniHPC. In such cases, the Delta T condition might never be met due to the low outdoor temperature, and without a configured maximum time, defrosting would not occur (in this case, defrosting would rely solely on the outdoor unit’s internal algorithms).

13.5 Defrost control

14.1 Firmware upgrade