If your APAC / Carrier / Brivis system has a NC-4 controller and is displaying error 52, your system has most likely overheated.
The same fault can appear on other brands, Daikin has error code E3, LG is CH34/33, Fujitsu is EE:00/EF:00.
Error 52 on Cooling (Summer)
The outdoor unit has overheated. This can happen during extreme heat, high 30's upwards. Other reasons are:
- Blocking the airflow of the outdoor unit.
- Outdoor fan not working.
- Turning the system on late in the day where the heat has set in, including inside the home.
- Running too many zones.
- Running the system below 23 degrees
Error 52 on Heating (Winter)
The indoor unit has overheated. This can happen for a number of reasons:
- Blocked return air filter
- Indoor fan not working.
- Turning the system on heat on a warm day.
- Running too little zones.
- Running the system above 23 degrees