Outside AC Unit Won't Turn On? What to Do Before Calling Apr 15, 2015Look for a blown fuse or tripped circuit breaker If there was a power surge, your air conditioner might have blown a fuse or tripped a circuit breaker. Look for this problem in two places: Your main electrical panel — On old homes this is a ‘fuse box’ while newer homes have a circuit panel. If it’s a fuse box, look for a blown fuseAir Conditioning · Repair & Maintenance Plug Fuse Box Cover Units - Fuse Accessories - Grainger If you are searching for a way to protect a motor in a HVAC unit, Grainger offers a plug fuse and fuse box cover to meet your needs. Whether you need to install a plug fuse box cover on a new heating or AC unit or complete a major electrical project, Grainger can help you find the right fuse cover.