York mini split unit has power but will not come on stand-by.

YORK MINI SPLIT 07-21

This unit has power,but will not come on with the remote or manualy. When the run relay contacts is briged it runs , so it seems that it is been kept off by some interlock or the controll board is faulty.
While the unit is running the run relay is energised and deenergised as a voltage is measured across the coil, but will not energise without the relay contacts being briged.The tubes on the outdoor unit also ice up after a while.Is this because the unit is running continuously without stoping.The aircon does cool very quickly.