Recently did a service on several Carrier heat pumps at a small commercial building (38YCC models). The 5 ton versions (three phase 230v)had Millenium Compressors by Carlyle. When the unit disconnect was shut off, a loud burping sound occured followed by about a minute of loud metallic clicking. Sounded like sticking a metal rod in some bicycle spokes. The noise came from the compressor. The pressures, etc were normal. The unit is only a year old. Has anyone ever experienced this. Called Carrier--they say they have had no problems and that it is new to them???