Used to work just fine and my mid and forward ac/heat systems work just fine. I have very limited electrical knowledge, but enough to know how not to shock myself and use a voltmeter. Where should I start to diagnose this issue? I'm thinking of pulling the panel off and looking behind just to see if wires are rubbing or something to that extent. Or should I start at the unit and work back to the panel? Any suggestions would be great, thank you.