Heat Pumps and Electric Heating - Carrier Heat Pump Power Wires Burned Off

5 year old Carrier air handler with heat pump- Digital thermostat needing no batteries. Turned heat on for first time this season. Stayed on for four hours then cut out, no reading on thermostat.
Opened air handler and main power wires burned and wire nuts melted. Checked and confirmed correct installation of circuit breakers.
Cut and rewired, installed new manual thermostat and it all works good.
Concerned it will happen again. Checked all connection- all tight.
Hmmm...sequencer ??
Tenant told me yesterday that when ac kicks on in summer, lights dim for a moment??
dazed and confused.-please assist
Thanks

You should really have a qualified service tech look at it, you could have the wrong size wire for the amp draw and or length of run or a problem with the elec heat. Either way, not something to fool with unless you KNOW what your doing:thumbup: