he said, you said...get your own electrician to take a look, not a friend...I suspect you are on shaky ground without proof...

TD

If the installation was incorrect then the circuit breaker should have tripped and protected the wiring. Your electrician friend needs to come to your house in order to determine the root cause of the problem. A remote diagnosis is not going to work.

The breaker in the garage did not do this. What
you see is overheating of the wiring from a bad connection immediately adjacent
to the melted wire; the original A/C installation technician likely did not
tighten the connection sufficiently in this disconnect box, if at all. If the garage breaker had
failed, the heating would be at the garage breaker connection. It isn't. The
heating comes about by what engineers call I-squared-R heating; the electrical
draw of the equipment (I, in amps), then squared, times the electrical resistance
of the connection (R, in ohms) equals heating (in Watts) at the connection.
When installed last summer, the connection was probably poor (some lower amount
of R), but it worked. As time went on and the joint was repeatedly heated
during HVAC operation, the terminal and wires began to oxidize more and more,
further increasing the resistance (R) and heating of the connection; it's the
snowball effect. Ultimately, R increases to the point that heating of the
connection reaches extreme levels and results in what you see now. Why wouldn't
the tech tell you this? The polite thing to say is that not everyone in
the trades understands the theory behind what they are doing. Bottom line is
that the melted wires are from a bad electrical connection immediately adjacent
to the melting; bad install last summer. But, to get any satisfaction from the
HVAC company, you may still need a written statement from a licensed
electrician to prove your point.

Thank you so much!