Came out to call for a system not cooling. Customer stated that a fuse had gone out on the AC system and customer was wondering what caused it. I replaced both 30 amp fuses and rechecked the system. Found no issues electrically or with how the system is running. Mentioned that we’ve had quite a few calls on fuses and believe they are going bad prematurely. Told him that we’d cover this call under 1st year warranty. Gave quote on adding piggy back returns in the two front bedrooms.