Assess the causeFollow the evidence.
Identify when the sound occurs and inspect levelling, contact points, accessible fans and the compressor start cycle.
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.
Record a short audio or video clip and note whether opening the door changes the noise.
Record the timing, previous work and accessible model label. Do not remove covers or handle live, refrigerant or pressurised components to obtain information.