A/C unit not cooling

[skennedy6009]

I have a 2015 Airstream with 2 A/Cs ducted system one is not cooling the air, I pulled the intake vents off to find the info sticker and found a wire hanging down (see pix) can anyone tell me what this wire is and does it need to be hooked up for the unit to work? As stated earlier I have 2 units one is a 15000 Heat pump and the other is a 13500 heat pump. It is the 13500 unit that is not cooling. I do hear the compressor kick on after the timer goes out so I am assuming the unit has lost it R410a coolant. Both units are Penguin II.
If you have something more I should check before buying a new unit I would love to hear it. Also if I need to buy a new unit do I have to buy the 13500 for replacement or can I jump to the 15000 unit and have the same wiring just a swap out.

[J. Morgan]

If you hear the compressor run and it isn't cooling, either it's lost it's charge or the reverser valve has failed. either one probably means a new unit in this day and age, and yeah, you should be able to swap in a 15,000 no problem.

I have no idea what the hanging wire is, I'm betting someone else does and will chime in.

[SeeMore]

I am probably wrong but looking at the wiring diagram for the stated unit it appears those two gray wires are the thermostat circuit for the heater...and they do NOT attach to the main control thermostat inside of the trailer. [The main control thermostat has about 7 small colored wires inside of an insulated sheath which runs to the relay box on the roof unit and are connect via a RJ45 coupler.] When the thermostat calls for heat, the small white wire from the control thermostat causes a relay inside of the roof unit box to activate, connecting the two heater T-stat wires together.

Given your compressor engages, I agree with J Morgan that you are highly likely dealing with a replacement and upsizing is not an issue.