Dometic SmartStart Soft Starter for FreshJet 5 Mechanical AC

If you've ever tried to start your rooftop air conditioner on a small portable generator and watched it stall, sputter, or trip the breaker, you already know the problem this thing solves. The Dometic SmartStart is a soft starter built specifically for the FreshJet 5 Mechanical series. It tames the big jolt of power your AC's compressor demands the instant it kicks on, and that one change opens up a lot of options for how you power your rig.

Here's what's happening under the hood. A standard air conditioner compressor pulls a huge surge of current at the moment it starts, often several times what it draws while running. That inrush is what overwhelms a small generator or an inverter. The SmartStart ramps the compressor up gradually instead of hitting it all at once, cutting that startup power demand by as much as 75 percent. Once the compressor is spinning, it settles into its normal running draw. The soft starter has already done its job.

What does that mean out at the campsite? It means a 2,000-watt inverter generator that never had a prayer of starting your AC suddenly can. It means you're not forced onto a loud, oversized generator just to get cool air. Folks running a battery bank and inverter get the same benefit, since the startup surge is usually the first wall they hit. We've seen plenty of campers add one of these and finally use the AC they've been hauling around unused for a couple of seasons.

Let's be straight about what it does and doesn't do, because that honesty saves you a return. The SmartStart reduces the startup surge only. It does not lower how many watts your air conditioner pulls while it's actually running. So if your generator can't handle the AC's steady running load, a soft starter won't fix that. It's the startup spike it's built for. And it works one air conditioner at a time. If you've got two rooftop units and you're hoping to run both off one undersized generator, this isn't the workaround for that.

Fitment matters here. This unit is matched to the Dometic FreshJet 5 Mechanical series specifically, running on 120 volts. If you've got a different air conditioner or a heat-pump version, check your model before you buy. The mechanical FreshJet 5 is the target, and that's where it drops in clean.

One more note on that "Mechanical" label in the name. The FreshJet 5 comes in more than one control style, and this soft starter is spec'd for the mechanical version, the one with mechanical controls rather than a fully electronic control board. Matching the soft starter to the right control type is what keeps the startup timing playing nice with the unit, so it's worth confirming which FreshJet 5 you're running before you order.

On the install side, this is a hardwired component, not a plug-in dongle. It wires in ahead of the compressor inside the AC unit, and it ships with the connections you need to tie it in. If you're comfortable working around 120-volt AC wiring and pulling the shroud off a rooftop unit, it's a very doable afternoon job. If you're not, have an RV tech handle it. There's line voltage involved, so respect it. The module itself measures about 12-1/4 inches long by 7 inches wide by 5 inches deep, and it's built to tuck into the AC's existing housing without a bunch of custom bracketry.

Bottom line, if you camp anywhere that shore power isn't guaranteed, or you're trying to get by on a smaller, quieter generator, the SmartStart is one of the highest-value upgrades you can make to a FreshJet 5. It's a small box that changes what your air conditioner is capable of running on. And on a hot afternoon at a no-hookup site, that's the difference between sweating it out and actually enjoying the trip.