Most RV AC complaints — poor cooling, freeze-up, water leaks — trace back to skipped maintenance. None of it is complicated. A once-a-year inspection on the roof and a clean filter inside covers most of it.
The two things I see most often in the shop: filters that haven't been cleaned in years, and thermostats set to temperatures the unit can never actually reach. Both cause the same result — the compressor runs constantly, the unit freezes up, and the owner thinks the AC is broken. Usually it isn't. Start with the basics before assuming it's a refrigerant or compressor problem.
A clogged filter restricts airflow across the evaporator coil. Restricted airflow means the coil can't absorb heat properly — and that leads directly to freeze-up. It also makes the unit work harder for less output and shortens compressor life.
RV AC filters are simple foam or mesh panels. They pull out from inside the ceiling unit, rinse clean with water, and go back in. There's no reason to skip this.
An RV air conditioner is not a residential unit. It has a fixed capacity — and it can only cool the space so far below the outside temperature. When the thermostat is set to an unrealistically low temperature, the unit never satisfies the call for cooling. It just keeps running.
A compressor that runs continuously without cycling off will eventually freeze the evaporator coil solid. Once frozen, the unit stops cooling entirely and shuts the compressor down to protect itself. At that point the fix is to turn the unit off, let it thaw completely — which can take an hour or more — and then restart with a reasonable setpoint.
The plastic shroud on the roof is easy to remove — usually a handful of screws around the perimeter. Most owners never take it off. Inside you'll find the condenser coil, the fan, and the drain channels. A year of road travel collects more debris up there than you'd expect.
This is also your chance to inspect everything that's hidden from ground level — and it's the most important maintenance step most owners skip entirely.
The AC unit sits on a rubber gasket between the rooftop unit and the ceiling assembly inside. That gasket creates the seal. Over time the rubber loses integrity — it compresses, hardens, or shifts. The mounting bolts that clamp everything together can also work loose, especially on units that weren't torqued down firmly from the factory.
A gap doesn't have to be obvious to cause damage. Water finds the path of least resistance, and even a small opening at the roofline means moisture is getting into the ceiling structure every time it rains.
RV air conditioners are the single largest electrical load in the coach. They're sensitive to low voltage — and running on an undersized or degraded power supply is hard on the compressor. Low voltage at startup is a common cause of compressor failure over time.
Before the first hot day of the season: clean the filter, pull the roof shroud and clear the debris, check the drain holes, spin the fan, snug the mounting bolts, and inspect the gasket. That's the full annual inspection. It takes less than an hour and it covers the most common causes of AC failure before they become problems.