Assess the causeFollow the evidence.
Compare external supply with valve operation and inspect the inlet screens and level-control information.
The exact model and operating conditions determine which tests apply. These are possible inspection directions, not a list of components that must be changed.
Before the appointmentKeep the useful details.
Close the supply tap safely if filling continues unexpectedly, and describe when it happens.
Record the timing, previous work and accessible model label. Do not remove covers or handle live, refrigerant or pressurised components to obtain information.