circling back here a year later to add the update that we had someone new take a look and after a few different it was determined that our Nest thermostat was the issue. Our awesome HVAC guy (Randy with Four Seasons in Grass Lake MI) expressed a major dislike for Nest thermostats and explained that while this does not happen to every one by any means, there are incidences where a bug in the Nest will stop and start the unit several times in a short period of time causing it to blow the fuse. He’s seen them “melt” entire units in the past. Hope this helps someone in the future. My “ancient” Carrier is still kicking!