Hello, I have a 1 ton split ac unit which I bought 2 months back. It not used much. In recent days when I turn on the system, the outdoor unit makes a rumbling and rattling noise like a trunk in wrong gear!! After 5-10 seconds it becomes silent and works well. This problem arises only when I turn on the system after a long break of time ( more than 24 hours) if I turn off the system and turn in on after few hours it starts without any unwanted sounds... Im wondering if there is some problem with the piping and refrigerant or valves or capacitor?. the chance of bad motor is ruled out as it runs like a charm after that initial rattling start up.. I'm just wondering what would be the problem and how serious it can be ? Can it pose problems in long term? Should I call a technician asap? Thanks in advance

Inspect the cage around the unit, perhaps there's part of the cage that's rattling (it happened to mine), and then perhaps when the rattle reaches its resonant frequency it stops...