A burning smell from the air conditioner is a serious warning sign of overheating wiring or motor trouble

https://winterhavenhomeacservice408.hexaforgey.com/posts/ac-replacement-decision-checklist-for-an-aging-and-unreliable-system

A burning smell from the air conditioner is a serious warning sign of overheating wiring or motor trouble. Turn it off immediately and contact emergency HVAC service.