Dometic Duo Therm 3311924.000 Analog CF Relay Board Kit

When the rooftop air conditioner in your RV quits switching the compressor or the fan the way it should, the relay board is one of the first parts a good tech reaches for. This is the Dometic Duo Therm 3311924.000, the analog CF relay board kit that replaces the older 3107541.009 board. It's the small circuit board that takes the low-voltage call from your thermostat and actually closes the high-current circuits that run the compressor and the fan motor. When it goes, the rest of the unit can look perfectly healthy and still do nothing.

Think of the relay board as the traffic cop between your thermostat and the guts of the air conditioner. Your wall control runs on a small signal. The compressor and fan motor pull real amperage. The board sits in the middle and uses relays to hand that power off cleanly, on demand. That's why a bad board shows up as odd behavior. The fan runs but the compressor never kicks in. The unit short-cycles. Or nothing responds at all even though you've got power at the plug. Swap the board and, more often than not, the system comes right back to life.

So how do you know it's the board and not something else? Start with the easy stuff. Confirm you've got shore power or a strong battery bank, check the breaker, and make sure the thermostat is actually calling for cooling. If the fan and compressor still won't respond correctly, and the wiring and capacitors check out, the relay board is the usual suspect. It's a common failure point on Duo Therm units that have been through a lot of heat cycles and a few rough summers. The good news is it's a repair, not a whole new air conditioner.

This is the analog CF version, and that matters. Duo Therm built these units around different control setups over the years, and the board has to match the control system your coach already uses. The 3311924.000 is the factory replacement for the 3107541.009, so if that's the number on your old board, this is your part. It drops into the same footprint and lands your existing wiring in the same spots, which keeps the job straightforward instead of turning into a rewiring project.

Installation is well within reach for anyone comfortable working around 120-volt and low-voltage wiring, but respect the power. Kill the shore power and the breaker before you open anything up. Take a photo of the wiring before you pull a single connector so you've got a reference to work back from. Move the connections over one at a time from the old board to the new one, seat everything firmly, and double-check your work before you restore power. If you're not comfortable inside an air conditioner, this is an easy job for an RV service tech and it won't tie up the bay for long.

While you're in there, it's worth giving the rest of the unit a quick once-over. Look for scorched connectors, corroded terminals, or a start capacitor that's seen better days. Fixing a loose or burnt connection now saves you from chasing the same symptom again next season. A clean install on a fresh board is the difference between a repair that lasts and one you're back to in a month.

We stock this as a genuine Dometic part, so you're getting the correct board and the factory warranty behind it, not a mystery box from who knows where. If your Duo Therm has gone quiet and you've traced it back to the relay board, the 3311924.000 gets you back to cold air without the cost of a full replacement unit. And if you're not sure it's the board, give us a shout before you order. We'd rather point you at the right part than sell you the wrong one.