Dometic 3313107.077 AC Heat Pump Control Board Kit

When the control board in your Dometic rooftop air conditioner gives up, the whole unit goes with it. No cooling, no fan, no heat. This is the replacement kit for that board. The Dometic 3313107.077 is a single-zone LCD relay control board built for the Blizzard NXT, Penguin II, and Cool Cat heat pump units, and it ships ready to connect.

Here's what it actually covers. The board fits Dometic Blizzard NXT units with the H551916 model prefix, Penguin II units in the 651915 and 651916 series, and Cool Cat units in the 441003 and 441004 series. If your rooftop unit is one of those and it came from the factory with a pre-installed control board, this is the part that runs it. Match your unit's model number against that list before you order. The prefix stamped on your AC's data plate is the number that matters, not the marketing name on the shroud.

The kit handles all three modes your heat pump unit needs. Cool, fan, and heat pump. That's the C/F/HP you'll see in the part description, and it's the reason this specific board matters for heat pump models. A cooling-only board won't drive the changeover that lets a heat pump warm the coach on a cold morning. This one does. So if you've got heat on the unit, you want the board that supports it.

It's a single-zone board, which means it controls one air conditioner. If your rig runs a single rooftop unit off one thermostat, that's exactly what you've got. Bigger coaches that run a multizone setup use a different board family, so again, the model prefix on your unit is the deciding factor. When in doubt, read the plate.

Why does a board fail in the first place? Usually it's not dramatic. Power surges from a shaky campground pedestal, a nearby lightning strike, water intrusion up on the roof, or just years of heat cycling under the sun. The symptoms are pretty consistent. The unit won't respond to the thermostat, it runs the fan but never kicks the compressor, the display goes dark or throws a fault, or the heat pump stops swapping over. Any of those and the board is a prime suspect. A meter and a little patience usually confirm it.

Swapping the board isn't a huge job, but it's electrical work up on a roof, so treat it with respect. Kill the power at the breaker and the pedestal before you touch anything. If you're comfortable pulling the shroud, tracing the harness connectors, and matching them one for one to the new board, you can handle this in an afternoon. If any of that sounds like a stretch, hand it to an RV tech. There's line voltage in these units and a mistake is expensive.

Because this is a genuine Dometic part, the connectors, the relay ratings, and the LCD interface all match what left the factory. No adapters, no guessing which pin does what, no fighting a generic board that almost fits. You pull the old one, you set the new one, you reconnect the harness. That's the value of buying the real board instead of a look-alike.

One honest note. This kit is the control board and its relay and display hardware. It's not the whole air conditioner, and it isn't a wall thermostat on its own. If your problem turns out to be the wall control, the fan motor, or the compressor, a new board won't fix it. Diagnose first, order second. But when the board really is the failure, this is the correct genuine replacement for those Blizzard NXT, Penguin II, and Cool Cat heat pump units, and it'll get your air conditioner back online.