Cut Wire at Furnace

[George]

Please help me figure out if this a problem or not. The furnace works but I have found a cut wire from the thermostat.
At the furnace there is a pair of wires from the thermostat. Both of these RED and WHITE wires are crimped to the furnace BLUE wire. The WHITE wire has been cut, see attached photo.
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The t’stat wiring diagram labels the RED as +12VDC and the WHITE as FURNACE.
The furnace wiring diagram labels the BLUE wire as THERMOSTAT.
The furnace BLUE/WHITE wire is not connected to anything. Labeled POWER TO THERMOSTAT.
Should this WHITE wire be repaired?
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I might mention that all 3 butt splices were tucked into the squirrel cage and the -12VDC splice was worn through. The white wire may have been cut by the squirrel cage but it seems unlikely.
If you're wondering why I have the cover off – I'm painting it. Suburban's idea of weatherproof paint leaves something to be desired. Chalked up after <2 years.
I've also sent this to Alliance Service and will post any response from them as I receive it.

 

[George]

Update: Alliance contacted me and advised repairing the white wire. I did so and the furnace fires and shuts down as expected.
I replied that I am still confused as to why the RED *and* WHITE wires are both terminated to the furnace BLUE wire. I also asked where typically this 2-conductor cable is spliced into the 6-conductor from the thermostat – at the rooftop A/C?

 

[George]

Update to Update: 🙃
Alliance Service confirms that the 2-conductor cable picks up the white wire from the thermostat at the rooftop A/C unit.
I haven't climbed up there but I suppose they just used both the RED and WHITE for redundancy. This actually saved me from an inoperative furnace since the white wire was cut.
May I add that replies from Alliance were timely and appreciated.

 

[brytonmar]

I'm diagnosing a similar issue with my 2023 382RK. I found the white thermostat wire cut and it doesn't appear to have ever been connected with the red and blue and appeared to be taped off with masking tape. I also found the blue/white wire which is hot at 13.7V from the motherboard, cut and just sitting outside the hole to the left of the heater box. I have not been able to get the blower to come on since the thermostat was tested not working by a technician a couple of years ago. The new thermostat drives the air conditioner, but not the heater, suspecting it is one or both of the wires that is the problem. If I touch the blue/white wire to the blue/red thermostat wire, the blower comes on. Trying not to fry anything, does anyone have a suggestion where the wires need to be hooked up? I could hook the white wire to the red and blue like this thread suggests, but I have no guess where the blue/white wire needs to go.

 

[brytonmar]

Looks like I probably just need to hook the white wire to the red and blue. The blue/white looks like it's not used and may be there to bypass the thermostat when needed although it's scary that a hot wire was just laying outside the box and not taped off. Waiting for reply from Alliance, I'll post if anything different from just hooking up the white wire. The white wire is hooked up to the thermostat in the correct place.

 

[George]

I spent 30 minutes composing a long trouble shooting procedure and my computer froze up and I lost it. 🤬
In any case what you describe doing is probably correct.
My white wire was in the crimp but cut above it so I felt comfortable just reconnecting it. Maybe you should look inside roof AC to see what happens to the brown wrapped 2-conductor cable and the white wire in the 6-conductor cable from the thermostat.