A jewelry store in Stockton California reported that their AC unit had gone down. Our technician arrived and first checked the breaker panel, confirming here was power to the unit. Found system not running due to a 24v short at the Y circuit, where a wire nut had fallen off and grounded causing 3amp fuse to blow. Our tech replaced the wire nut with newer one and replaced blown fuse. System cycled on in cooling with a 23deg split. Unit is now operational.