T12RB thermostat issue (from last year)

[Mtnwlm]

Finally found the problem with the T12RB thermostat that caused my furnace problems.

A wire running from the heat pump/air conditioner to the furnace was not run properly (factory) - the wire was caught somewhere under the sink/stove and the insulation got rubbed off - had to pull like crazy to get it loose and taped it up - everything works like it's supposed to.

I've replaced thermostats, mounted a separate thermostat and running another thermostat wire.

Should anyone encounter a similar issue - I suggest checking the existing wiring between the heat pump & air conditioner going to the furnace first.