Hi Customer (name blocked for privacy);

What you are hearing is the compressor coming off of the mounts and slamming back down on them. Or the compressor jumping, swinging, or in general not being properly restrained by the rubber mounts.

This can be easily checked and repaired. Just watch the compressor as it stops (unplug it when it is running).

If the compressor is restrained and there is still a loud clunk then something inside the compressor is coming loose and the whole unit must be replaced. This is not very likely as this would cause the compressor to fail in short time.

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