Arrived to find compressor on lockout Reset power to find low on r410a Investigated system to find no signs of Freon leak at this time Topped RTU with 2lbs r410a and tested system operation. All okay at this time made client aware to call back in of stops cooling again and can further assess for leaks and hopefully at that time if there is a leak it will be visible. System had dropped 3 degrees since I had been on site