The situation
A customer has two identical Dometic Blizzard NXT units with heat pump on his coach and needs to replace one of them. It's a ducted installation with no cutout in the ceiling, and he wanted to know his options.
The short answer
If you want to stay with Dometic and keep running everything from one thermostat, the path is:
- FreshJet 5 with Heat Pump — in white or black
- Connect Essential thermostat, 9610007991 — this is the piece that lets the Blizzard you're keeping, on its CCC2 board, still talk to the new FreshJet 5
- Three RJ-11 to RJ-45 adapter harnesses
You will not need to run additional wire behind the wall.
Why
The obstacle in a two-unit coach is never the air conditioner — it's making the old and new units share a thermostat. Your existing Blizzard NXT runs on a CCC2 board. A FreshJet 5 Heat Pump is a newer control generation. Left alone they don't cooperate, and the usual assumption is that you're stuck replacing both units or running a second thermostat.
The Connect Essential 9610007991 is what resolves it. It's a backward-compatible replacement for CCC2 thermostats that also speaks to FreshJet units with pre-installed electronic controls — so it sits above both generations at once and runs them from a single point. It's single and multi-zone, handles heat pump plus furnace, and switches automatically from heat pump to furnace when outdoor temperatures approach freezing.
The wiring is the other half. Legacy Dometic multi-zone CCC and CCC2 systems ran on RJ-11 cable. Connect Essential and FreshJet 5 Heat Pump use RJ-45. The adapter harnesses bridge the two, which is precisely why the wire already in your walls stays where it is.
Three is the count for this configuration, and here is where each one goes:
- One at the thermostat
- One connecting the thermostat wire to the FreshJet 5
- One connecting the FreshJet 5 to the daisy-chained wire running to the Blizzard NXT
The total varies by how many rooftop units are on the chain and where each sits in the daisy-chain sequence, so a coach with a different layout may need a different count.
What to do
- Confirm the unit you're keeping is on a CCC2 board. That's the assumption this whole approach rests on.
- Pick your FreshJet 5 Heat Pump in white or black.
- Add the Connect Essential 9610007991. Your existing thermostat is being replaced — this isn't optional in this configuration.
- Order three RJ-11 to RJ-45 harnesses. They're inexpensive relative to the rest of the job and the install stalls without them.
- Leave the wall wiring alone. No new runs are needed — that's the entire point of the adapters.
- Have a qualified RV technician handle the install, including RV-C or CMC protocol configuration on the new thermostat.
Still not sure?
Tell us how many rooftop units you have, what thermostat is on the wall now, and which unit you're replacing, and we'll confirm the exact harness count before you order. Ask us here.