Installing a rooftop RV air conditioner is a one-day job for most DIYers if you have the right tools and follow two non-negotiable rules of roof waterproofing. Most "leaky AC" problems we see at OutEquipPro aren't product failures — they're installation mistakes that could have been caught in 60 seconds. This guide walks you through the process with the exact specs, cutout dimensions, torque values, and pro tips straight from our Summit 2 and Glacier Pro installation manuals.
Spring is the busiest install season for a reason: you want the unit mounted, sealed, and tested before the first 90°F afternoon. Here's how to do it right the first time.
Quick Answer: The Install in One Paragraph
For a 12V OutEquipPro Summit 2 or Glacier Pro, you'll cut a 14.1" × 14.1" opening in your roof (or use an existing 14" × 14" MaxxFan opening), seat the included EPDM gasket, position the outdoor unit so the chassis drainage cutout stays outside the gasket, route the included 6 AWG power cord from a capable LiFePO4 battery bank to the indoor connection point, and seal the perimeter with a UV-resistant RV sealant. Plan on 4–6 hours start to finish. Difficulty: intermediate. The hardest part isn't the install — it's getting the gasket positioning and unit offset right so water never gets inside.
Before You Start: Pre-Installation Checklist
Walk through this list before you cut anything. Skipping it is the most common reason installs go sideways.
Roof Condition
- Roof structure can support the unit's weight. Summit 2 = 45 lbs total. Glacier Pro = 68 lbs total. Skyeline mini-split outdoor unit = 52 lbs.
- Roof thickness is between 1.5" and 3.5" (Summit 2 standard range, measured from outer roof skin to interior ceiling panel). Thinner roofs (van conversions) need a wooden support frame around the opening. Thicker roofs (3.5"–8.7") require the optional Air Duct Extension Kit (longer duct, longer rods, longer screws — sold separately).
- Roof is flat and level. Up to 5° of slope (front-to-back or side-to-side) is acceptable; rear leveling foam blocks are included with the Summit 2.
- No hidden wiring, plumbing, or structural ribs below the cutout area. Check from inside with a stud finder or by removing the headliner.
Measurements
Summit 2:
- Standard square cutout: 14.1" × 14.1" (358 × 358 mm) — direct fit for replacing a standard RV vent or MaxxFan
- Minimum rectangular cutout: 14.1" × 10.3" (358 × 262 mm) — uses the universal strip gasket
- Outdoor unit footprint: 28.3" × 28.3" × 6.3" tall
- Required clearance: at least 2" on left/right/rear from any solar panels or accessories
Glacier Pro:
- Minimum opening: 14.1" × 13.7" (360 × 350 mm)
- Maximum opening: 28.7" × 22.8" (730 × 580 mm)
- Option 1 — 14.1" × 14.1" opening: uses an existing RV vent hole, but you'll need to drill 4× M8 rod holes and 4× M6 trim holes (template included)
- Option 2 — 18.1" × 14.1" opening: the recommended approach; mounting holes are visible from inside and no extra drilling is required
- Outdoor unit footprint: 35.4" × 34.6" × 7.1" tall
- Required clearance: 2–3" on all sides
Electrical Capacity
- 12V LiFePO4 battery bank with 100A continuous BMS minimum. A standard 50A BMS will trip during turbo cooling on Summit 2 (58A) or Glacier Pro (62A).
- Compliant with NFPA 1192 and NFPA 70 (NEC) in the US, or CSA C22.1 / Z240 in Canada.
- Battery sized for runtime goal. 230Ah lithium ≈ 6–7 hours eco / 3–4 hours turbo. 460Ah ≈ 12–14 hours eco — true overnight cooling. (See our Battery Sizing Guide for the math.)
Tools & Materials
| Tool / Material | Purpose | Notes |
|---|---|---|
| Jigsaw with metal/fiberglass blade | Cut roof opening | Painter's tape on the shoe to prevent scratches |
| 3/8" drill + step bit | Pilot holes + stud holes | Step bit useful for fiberglass |
| Tape measure + carpenter's square | Mark cutout precisely | Measure twice. Cut once. |
| UV-resistant RV sealant | Perimeter waterproofing | Sikaflex 221/252, Dicor lap sealant, or equivalent |
| Included thick power cord | DC power run | 12V units = 6 AWG; 24V/48V units = 8 AWG |
| Included inline fuse | Overcurrent protection | Pre-installed on the positive cord, properly sized for the unit's current |
| Cable gland or rubber grommet | Seal cable pass-through | If using separate roof opening for power |
| HVAC aluminum foil tape | Seal foam cover | If routing cable through the return air duct |
| Heat shrink ring terminals | Battery terminations | Crimp + heat shrink |
| Multimeter | Verify voltage | Should read 12.5–13.5V at the lugs (for 12V systems) |
| Torque wrench (small range) | Final tightening | Summit 2 = <1.5 Nm; Glacier Pro = <1.5 Nm |
| Helper | Lifting outdoor unit onto roof | Especially for 68 lb Glacier Pro |
The Two Golden Rules of Waterproofing
This is the single most important section of this guide. Every interior leak we troubleshoot at OutEquipPro traces back to one of these two rules being broken.
Rule 1: The Chassis Drainage Cutout Must Stay OUTSIDE the Gasket Ring
Look at the bottom of the outdoor unit. There's an open cutout section that exposes the condenser coils and fan to outside airflow — and it's also where condensate water drains out onto the roof.
This cutout must sit completely outside your roof opening, sealed against the solid bottom panel of the unit by the gasket.
Test: From inside the RV, look up through the roof opening before you fully tighten the bolts. You should see only the solid metal underside of the unit and a continuous gasket. If you can see the open chassis deck or the coil cutout, water will pour into your cabin the first time it rains.
Summit 2 critical detail: When using the 14.1" × 14.1" standard opening, you must offset the unit's air duct 2.36"–3.15" REARWARD (toward the back of the vehicle). This is the exact offset needed to keep the drainage cutout outside the gasket on the standard opening. The installation manual specifies this; skipping it is the #1 reason customers report leaks on otherwise correct installs.
Rule 2: The Mounting Studs Must Pass INSIDE the Gasket Ring
The threaded rods that secure the outdoor unit to the roof must penetrate inside the sealed perimeter — not through your gasket and not outside it. If a rod passes through the gasket itself, it creates a permanent leak point that no amount of Sikaflex will fully fix.
On the Glacier Pro, the manual labels these as #7 (M6 trim screws) and #8 (M8 mounting rods) holes — both must sit inside the gasket area.
When the gasket is properly compressed, the rods come down into the cabin through dry, sealed roof penetrations. The interior trim then covers the rod and hardware.
Get these two rules right and your install will be bone-dry for the life of the unit.
Step-by-Step Installation
Step 1: Mark and Cut the Roof Opening (45 min)
- Center your cutout location with at least 4" of clearance on all sides for the gasket and sealant zone.
- Tape off the cut lines with painter's tape (protects the roof finish from your jigsaw shoe).
- Drill 3/8" pilot holes in each corner.
- Cut the opening with a jigsaw, working from corner to corner. Have a helper steady the cut piece.
- Deburr the edges with a file or sandpaper. Wipe with isopropyl alcohol.
Replacing a MaxxFan? Remove the existing fan, scrape off the old butyl/sealant down to clean roof material, and skip to Step 2. The 14" × 14" opening is already correct for Summit 2 or Glacier Pro Option 1.
Step 2: Install the Gasket (15 min)
Summit 2: Two gaskets are included in the box.
- For 14.1" × 14.1" openings: Use the pre-sized Square Gasket. Remove the adhesive backing, center it over the cutout, and press firmly around the perimeter.
- For 14.1" × 10.3" or non-standard openings: Use the Universal Strip Gasket. Trim it to length and ensure the ends meet tightly with no gap.
Glacier Pro: A single flexible EPDM gasket is included, with pre-punched holes for support rubber columns that prevent long-term deformation.
- Apply the gasket around the cutout.
- Stretch and trim to fit snugly.
- Insert the support columns into the punched holes (trim them shorter if a hole falls on a roof rib).
Step 3: Apply Weather Sealing (15 min)
- Apply a continuous bead of UV-resistant RV sealant (Sikaflex 221/252 or Dicor) around the outer edge of the foam gasket where it meets the roof.
- Smooth the bead with a gloved finger or plastic applicator for full, gap-free coverage.
- Do not put sealant under the gasket face — the gasket needs to compress directly against the roof to seal properly.
- Cure time: 24–48 hours before exposing to rain or road spray. Plan accordingly.
- Apply a second bead along the inside edge of the roof opening for extra protection.
Step 4: Position the Outdoor Unit (30 min — needs a helper)
- Lift the outdoor unit onto the roof. Summit 2 is manageable for one person at 43 lbs; Glacier Pro at 65 lbs needs two people.
- Summit 2: Offset the air duct 2.36–3.15" rearward toward the back of the vehicle (per the manual) so the drainage cutout clears the gasket.
- Summit 2 leveling: Place the included hard foam blocks under the rear corners. Use a bubble level — slope up to 5° in any direction is acceptable.
- Glacier Pro: If you cut the larger 18.1" × 14.1" opening, the unit drops in with mounting holes visible from inside. If you used the 14.1" × 14.1" opening, mark the M8 (#8) and M6 (#7) hole positions through the included template and drill before final placement.
Step 5: Secure the Unit From Inside (30 min)
Summit 2:
- From inside the cabin, position the included Galvanized Steel Mounting Plate (painted black) against the roof opening. For thin roofs, the plate must rest against your added wooden support frame, not directly against thin sheet metal.
- Insert the four threaded rods through the plate into the threaded inserts on the base of the outdoor unit.
- Hand-tighten in a crisscross pattern to compress the gasket evenly.
- Torque to less than 1.5 Nm — basically hand-tight plus a quarter turn. Overtightening will crush the roof structure or damage the unit base.
Glacier Pro:
- Insert the M8 threaded rods (chosen length based on roof thickness) into the #8 mounting holes from inside the cabin.
- Hand-tighten four nuts to draw the rods down to the unit base.
- Position the mounting brackets onto the rods, then secure with washers and anti-slip nuts.
- Torque to less than 1.5 Nm in a crisscross pattern. Do not overtighten.
- Trim excess rod length if needed.
Step 6: Route the Power Cable (45 min)
The Summit 2 manual lists three approved methods. Pick the one that fits your build:
- Option 1 — Separate roof opening: Drill a clean round hole near the unit and seal with a cable gland or rubber grommet.
- Option 2 — Through the return air duct (no new roof hole): Open the outdoor unit's top cover, free the power cord at the rear chassis exit, lift the black foam evaporator cover, create a small hole in the foam aligned with the return duct, feed the cable through into the cabin, then seal the foam with HVAC aluminum foil tape.
- Option 3 — Notch the gasket: Cut a small notch in one corner of the gasket and route the cable under the gasket through the main roof opening. Apply RV-compatible sealant around the wire at the notch.
The Glacier Pro supports Option 1 and Option 3 (no return-duct route).
Wiring the DC power:
- Route the included thick power cord from the battery to the unit's connection point. Our 12V units come equipped with robust 6 AWG wire, while the 24V and 48V units include 8 AWG wire. Use grommets at every panel pass-through to prevent chafing.
- At the battery end: You'll notice the positive lead of your power cord already features an included inline fuse properly sized for your specific unit's current draw. Crimp and heat-shrink ring terminals to attach it securely to your battery.
- At the unit end: Connect to the labeled +/− terminals.
- Before powering on, measure with a multimeter. You should see 12.5–13.5V at the unit's terminals for a 12V system. If you see significantly less at the lugs, check your connections.
Step 7: Seal the Ceiling Gap (10 min — easy to skip, big cooling impact)
Most RV and van ceilings have a gap between the structural roof and the interior ceiling panel. If left unsealed, hot air trapped in this cavity gets pulled into the return air intake, dramatically reducing cooling efficiency.
Use the included foam insulation strips to block both sides of the opening before installing the indoor panel. Trim to fit and ensure full coverage. This step matters most in larger ceiling cavities and hot-climate applications.
Step 8: Install the Indoor Panel and Wiring (30 min)
- Place the decorative panel trim between the ceiling and the indoor panel assembly.
- Push the indoor panel up until the air ducts firmly connect with the outdoor unit (sealed air path).
- Connect the keyed wiring harnesses: 3 plugs for cooling-only models, 4 plugs for cooling + heating models.
- Critical: position the temperature sensor. Find the black sensor wire (round head) and secure it in the pre-looped zip tie above the return air grille. Do not let it hang near the cold air outlets — if cold air blows directly on the sensor, the unit will read an artificially low temp and cycle off prematurely.
- Fasten the indoor panel with the included long and short screws.
For the Glacier Pro: insert M6 threaded rods through the #6 holes, align the decor trim, and tighten the nuts evenly to pull the trim flush against the ceiling. Don't overtighten — the trim will deform or show gaps.
Step 9: First-Run Testing (15 min)
- Power on. Run Fan Only mode first to verify the blower spins freely.
- Switch to Sleep Cooling (lowest amp draw) and let the unit run 5–10 minutes. Verify cold air output and no error codes.
- Step up to Eco then Turbo to confirm full performance. Listen for unusual vibration — if you hear rattling, check that all four mounting rods are evenly tightened.
- Download the OutEquip app (Apple App Store / Google Play) to pair Bluetooth control. Range is ~30 ft.
Important: Do not run the cooling function when ambient temperature is below 40°F — this can cause frost inside the unit.
Special Cases We See in Customer Support
Ram ProMaster (Ribbed Roof)
The ProMaster's deep roof channels make a flat gasket seal tricky. Both manuals address this:
- Notch the gasket to match the contours of the roof ribs.
- Trim or use leveling shims if a mounting hole or gasket section falls on a rib.
- Apply extra sealant at all rib transitions and gasket joints.
- The included gaskets are designed for this — a third-party gasket is not required.
- Recommended path on a ProMaster Glacier Pro install: cut the 18.1" × 14.1" opening so the unit drops in cleanly.
Sprinter (Double-Layer Roof)
Some Sprinter generations have a double-skin roof creating a gap between outer roof and inner ceiling. Standard mounting hardware may not seat fully. Fixes: use the Air Duct Extension Kit (longer rods + extended air duct, sold separately) or build a custom backing plate to span the gap. Email support@outequippro.com with your VIN — we ship the right hardware free if your build qualifies.
Replacing a MaxxFan or Fantastic Fan
Easiest install scenario. The 14" × 14" opening is a direct fit for Summit 2 or Glacier Pro Option 1. Power audit first: a 200Ah lithium bank with ~370W solar (typical MaxxFan setup) gives 4–6 hours of AC turbo runtime or 6–7 hours in eco — afternoon naps and pre-bed cool-down, not all-night cooling. Plan to upgrade to 460Ah lithium for overnight off-grid AC.
Skyeline Mini-Split (Different Install Profile)
The Skyeline is a split system — separate indoor and outdoor units connected by 10 ft pre-charged refrigerant lines and a signal cable. Outdoor unit can mount vertically (rear of van) or horizontally (under-chassis or roof). Indoor unit is wall-mounted at 25.1" × 13.1". No roof cutout required, which makes it the right choice for builds where roof real estate is already taken by solar.
Drainage: Where Does the Water Go?
Both Summit 2 and Glacier Pro use gravity drainage. Condensate drips into a pan inside the outdoor unit and exits through built-in slots on the left and right sides of the bottom chassis — directly onto the roof, where it runs off naturally. No external drain hose is required.
If your van has no factory rain gutters and you're worried about water streaking down the sides or pooling under solar panels, you can attach a small drain hose to the chassis outlets and route it to the rear. Optional, not required.
Why 12V Installation Is Simpler Than 120V
If you've ever installed a traditional rooftop AC, you know the headaches: shore power panel modifications, GFCI breakers, transfer switches, and inverter sizing if you want any battery capability at all.
A 12V install skips all of that:
- No inverter required. The unit runs directly off the battery bank.
- No 120V panel modifications. The DC system is independent of any shore power infrastructure.
- No transfer switch. The AC just draws from the battery, which can be charged by shore, solar, or alternator.
- No generator needed for off-grid use. This is the entire reason 12V exists.
The trade-off: you need a properly sized lithium battery bank and a real DC-DC charger if you want to charge while driving. (A cigarette-lighter port will not charge a battery that powers an AC — it's limited to 10–15A and can overheat.)
When to DIY vs. Call a Pro
You can DIY this install if:
- You're comfortable with a jigsaw and a multimeter
- Your roof is flat fiberglass or aluminum (not double-layer or composite)
- You have a LiFePO4 battery bank
- You can recruit one helper for the lift
Call a pro if:
- You have a fiberglass-over-foam roof and are nervous about delamination
- You need to add the battery bank, DC-DC charger, and solar at the same time as the AC
- You're working on a high-end Class A or Airstream where mistakes are expensive
- You don't have a comfortable workspace (covered garage with the rig at a manageable height)
Pro install typically runs $400–$700 in the US for a drop-in replacement; full system installs run $1,500–$3,000.
Frequently Asked Questions
Can I install an RV air conditioner myself?
Yes — if you're comfortable cutting a roof opening, routing the included power cord, and following manufacturer specs, this is an intermediate-level DIY job. Plan 4–6 hours. The most common DIY mistake is gasket misalignment combined with skipping the rearward air-duct offset (Summit 2). Following the "two golden rules" of waterproofing in this guide will avoid that.
What wire gauge do I need for an RV air conditioner?
You don't need to guess—our units come with a heavy-duty power cord included right in the box! For the OutEquipPro Summit 2 and Glacier Pro 12V models, the included wire is 6 AWG. If you are installing a 24V or 48V unit, the included wire is 8 AWG. Even better, each power cord features an inline fuse pre-installed on the positive lead that is matched perfectly to that unit's current requirements.
Will a 12V AC fit a standard RV roof opening?
Yes. Both Summit 2 and Glacier Pro fit the standard 14.1" × 14.1" (358 × 358 mm) RV roof opening — a direct drop-in for MaxxFan or Fantastic Fan replacements. The Glacier Pro also offers an alternate 18.1" × 14.1" cutout that allows a no-extra-drilling install.
How long does it take to install a rooftop RV air conditioner?
A drop-in replacement on an existing 14" × 14" opening takes 3–4 hours. A fresh install (cutting a new opening, running the new DC power cord, and completing battery connections) takes 4–6 hours for an experienced DIYer. Add 1–2 hours for ribbed roofs (ProMaster) or 24–48 hours of sealant cure time before exposing to rain.
Do I need to reinforce my RV roof for a 12V air conditioner?
For factory RV roofs (fiberglass with internal cross members) in the standard 1.5"–3.5" thickness range, no reinforcement is needed. Summit 2 weighs 45 lbs total — significantly less than a traditional 13,500 BTU rooftop AC at 75–95 lbs. For DIY van conversions with thin sheet-metal roofs (<1.5"), the manual specifies adding a wooden support frame around the opening so the mounting plate clamps against rigid material, not thin metal. For thick roofs (3.5"–8.7"), use the optional Air Duct Extension Kit.
Related Articles
- How to Size Your Solar System to Run a 12V RV Air Conditioner
- Best 12V RV Air Conditioners for Boondocking in 2026
Ready to upgrade your RV cooling this spring? The OutEquipPro Summit 2, Glacier Pro, and Skyeline mini-split are all in stock and ship from US warehouses. Free installation hardware and heavy-duty power cables with every order. Browse the full lineup at outequippro.com.
Have an installation question we didn't cover? Email support@outequippro.com — we respond within one business day with specific advice for your rig.
