Came out to call for a no cool on a unit we did a repair on a couple of weeks ago. Last tech found a blown control board fuse, tried to find a short, but wasn’t successful. System worked after put another fuse in. I checked system over and found a bad transformer. I found a short in 24 volt wiring that was exposed externally of the system. Replaced transformer, and fixed wiring. Replaced fuse on control board and cycled system on. Checked operation of system to confirm unit was operating properly.