Quick Answer
If your 12V RV air conditioner is dripping water inside the cabin, the first thing to know is that making water is normal — a cooling AC pulls humidity out of the air and that condensate has to go somewhere. The problem is almost never the unit "leaking"; it's that the condensate drain path is blocked or the gasket was installed wrong. Work through it in this order: (1) confirm the rig is level, because parked on a steep incline the drain tray overflows toward the low side; (2) check the external drain slots on the left and right of the outdoor chassis for leaves, pine needles, or sealant smeared over them; (3) check the gasket seal — if the unit sits too far back the gasket can bridge the roof cutout, and over- or under-torqued bolts both break the seal; and (4) confirm sealant was applied only around the outer edge of the gasket, never underneath its face. The two rules that prevent leaks at install time: the chassis drain opening must stay OUTSIDE the gasket ring, and the mounting studs must stay INSIDE it. Get those right and the water drains onto the roof where it belongs.
First: condensation is supposed to happen
Let's clear up the single biggest misunderstanding we see in the support queue. A rooftop AC works by passing warm cabin air over a cold evaporator coil. Just like a cold glass of iced tea sweats on a summer day, that coil pulls moisture out of the air and it collects as liquid water. A unit that makes water is a unit that's cooling well.
On the Summit 2 and Glacier Pro, that condensate is designed to collect in the outdoor (rooftop) half of the unit and drain out through drainage outlets on both the left and right sides of the bottom chassis, straight onto your roof, then off the edge. You will sometimes see water dripping off the side of your RV on a humid day. That's the system working correctly.
So the real question is never "why is it making water?" It's "why is the water ending up inside instead of draining onto the roof?" That's a drainage or sealing problem — and it's fixable.
How to tell normal condensation from an actual leak
Run this quick triage before you do anything else.
| Sign | Points to | What it means |
|---|---|---|
| Water dripping off the roof edge outside | Normal condensation | Drains are working — no action needed |
| Water inside only when parked on a slope | Drainage / leveling | Tray overflowing to the low side; level the rig |
| Water inside even when level, drains look clear | Gasket / seal | Suspect gasket bridging the cutout or uneven bolt torque |
| Water inside after rain, AC off | True rain leak | Sealant edge or gasket compression failure, not condensate |
| Drains visibly clogged with debris | Blocked drain path | Clear the slots; tray is overflowing inward |
The tell: condensate problems happen while the AC is running and cooling. A drip that shows up after rain with the unit off is a rainwater intrusion problem — same gasket and sealant fixes apply, but it's not the coil's condensate.
Cause 1: the rig isn't level
This is the easiest one and the most overlooked. The condensate tray relies on gravity to reach the drain outlets. Park on a steep enough incline and the water pools toward the low corner faster than it can drain, the tray overflows, and it finds its way to the cabin ceiling.
Fix: level the rig, or at least avoid leaving the AC running hard while parked nose-down or heavily off-camber. If you only ever see interior water on a slope, this is your answer — nothing is broken.
Cause 2: the external drain slots are blocked
The drain outlets sit low on the outdoor chassis, which makes them easy targets for roof debris.
- Leaves and pine needles packed into the slots after parking under trees.
- Sealant smeared over the drains during a DIY install — well-meaning, but it traps the water it was supposed to let out.
- Road grime built up over a season.
Fix: with the unit off and cool, inspect the left and right drain slots on the bottom of the outdoor chassis and gently clear anything blocking them. Never seal over a drain. If condensate has nowhere to exit, the tray backs up and overflows inward — which looks exactly like a leak but is just a plugged drain.
Cause 3: the gasket seal (the install issue behind most "real" leaks)
If the rig is level and the drains are clear but you still get interior water — especially during rain — the gasket is the prime suspect. A rooftop AC seals to your roof with a foam gasket that has to compress evenly around the roof cutout. Two specific failures show up again and again:
- Unit positioned too far back. If the AC is shifted rearward during install, the gasket can end up bridging the roof cutout instead of sealing flat around it, leaving an open path for water.
- Uneven or wrong bolt torque. Under-torqued bolts don't compress the gasket enough to seal; over-torqued bolts crush and distort it (and can stress the base of the unit). Both leak. The target is hand-tight, roughly 1–1.5 Nm — snug plus a small final turn, not gorilla-tight.
The Summit 2 ships with two gaskets for exactly this reason: a pre-cut square gasket sized for a standard 14"×14" opening, and an oversized universal foam strip you trim to fit non-standard or ribbed roofs (like a ProMaster).
The Two Golden Rules of waterproofing (do these at install)
These are the two rules our install team comes back to on every leak case. When you position the gasket, mind two zones:
- Chassis drainage stays OUTSIDE the gasket ring. The drain opening at the bottom of the outdoor unit must sit outside the sealed gasket area, so condensate drains onto the roof. If the gasket ring closes over the drain, water has nowhere to go but inside.
- Mounting studs stay INSIDE the gasket ring. The threaded mounting rods must pass through inside the sealed area, so each bolt penetrates the roof at a point the gasket protects — no bolt hole left exposed to water.
Get the drain outside and the studs inside, and the geometry of the seal does the waterproofing for you.
Sealant: where it goes (and where it must not)
Sealant supports the gasket — it doesn't replace it. The pattern we recommend:
- Outer perimeter only. Run a continuous bead of a quality RV/marine polyurethane sealant (e.g., Sikaflex 221 or 252) around the outer edge where the gasket meets the roof.
- Trimmed joints. If you cut or splice the universal strip to clear roof ribs, add extra sealant at those cut joints — they're the weak points.
- Never under the gasket face. The gasket needs to compress to seal. Sealant smeared under its face props it up and prevents an even squeeze. Seal the edges, not the underside.
A note on roof thickness: these units are designed for a roof in the 1.5"–3.5" range. Double-layer roofs (some Sprinters) may need bracket adjustment so the gasket still compresses correctly — confirm the manual before you torque anything down.
A simple way to decide what's wrong
- Is water dripping off the roof outside? Yes → normal, you're done.
- Is the rig level? No → level it and re-check.
- Are the drain slots clear? No → clear them (never seal over them).
- Still leaking while level with clear drains? → gasket/torque. Check the unit isn't shifted rearward, re-seat the gasket, and set bolts to even ~1–1.5 Nm hand-tight.
- Only leaks in the rain, AC off? → sealant edge / gasket compression, not condensate. Same gasket fixes plus a fresh perimeter bead.
Nine times out of ten this lands on a blocked drain or a gasket that wasn't compressed evenly — both DIY-fixable on the roof in an afternoon.
When to contact support
Reach out if: the seal looks correct and the drains are clear but interior water continues; you find cracked or badly distorted gasket material; or you're unsure whether your roof type compresses the gasket properly. OutEquipPro support is reachable by email and online chat, and units carry a 1-year warranty (with an extended option if purchased within 30 days). Send photos of the roof install and the drain slots — that's the fastest path to a real diagnosis. (For a cooling-performance issue rather than water, see our 12V RV AC not cooling guide.)
FAQ
Q: Why is my RV air conditioner dripping water inside?
A: Almost always a blocked condensate drain or a gasket sealing problem — not a broken unit. The AC pulls humidity from the air and that water normally drains onto the roof through outlets on the left and right of the outdoor chassis. If those drains are clogged, the rig is parked on a slope, or the gasket wasn't compressed evenly at install, the tray overflows inward. Level the rig, clear the drain slots, and check the gasket seal.
Q: Is it normal for a 12V RV AC to drip water?
A: Yes — dripping water outside, off the roof edge, is completely normal and a sign the unit is cooling well. Cooling pulls moisture out of the cabin air and it has to drain somewhere. It's only a problem when the water ends up inside the cabin, which points to drainage or sealing, not the cooling system.
Q: How do I know if it's condensation or a real leak?
A: Condensate problems happen while the AC is running and cooling, and usually track with a blocked drain or an off-level rig. A drip that appears after rain with the AC off is rainwater intrusion — a gasket compression or perimeter-sealant issue. Both are fixed at the gasket; the difference just tells you where to look first.
Q: How tight should the mounting bolts be on a rooftop RV AC?
A: Hand-tight — roughly 1–1.5 Nm, snug plus a small final turn. Under-tightening leaves the gasket uncompressed and leaky; over-tightening crushes the gasket and can stress the base of the unit. Tighten evenly so no corner is looser than the others.
Q: Do I need to seal under the gasket?
A: No. The gasket needs to compress to seal, and sealant under its face prevents an even squeeze. Apply a continuous bead around the outer perimeter where the gasket meets the roof, add extra sealant at any trimmed joints, and leave the underside clean.
Q: What are the Two Golden Rules of waterproofing?
A: (1) Keep the chassis drain opening outside the gasket ring so condensate drains onto the roof. (2) Keep the mounting studs inside the gasket ring so every bolt penetrates a sealed area. Drain outside, studs inside — that geometry is what keeps water out.
