The thing that separates a good RV flipper from someone who just cleans up old rigs is systems thinking. When one component fails, I always ask what else failed alongside it, what caused it, and what’s about to fail next. RV systems are connected in ways that aren’t obvious until you’ve taken enough of them apart. On the Highland Ridge Open Range units I’ve flipped, the rooftop AC is one of the first things I put on the lift — a failed run capacitor is almost never the whole story, because the capacitor usually dies because the fan motor has been struggling, drawing excess current, and running hot for longer than it should have. Left undiagnosed, you replace the capacitor, hand the rig to a buyer, and two weeks later the compressor is gone — so this guide walks you through both components together, the way the repair actually needs to be done.
Parts & Tools You’ll Need
- RV AC dual run capacitor (Dometic/Coleman-Mach)
- Rooftop AC fan motor
- RV AC thermostat / control board
- AC evaporator/condenser coil cleaner foam
- Rooftop AC shroud / outer cover
- AC roof gasket & self-leveling lap sealant
- Fin comb / coil straightener tool
- Non-contact infrared thermometer
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Step-by-Step Repair Guide
Step 1: Diagnose AC System & Safety Prep
Start by turning off your RV’s main electrical panel and the AC unit itself, waiting at least five minutes for capacitors to discharge completely. Use your non-contact infrared thermometer to check current cooling performance, and listen for unusual noises from the rooftop unit to confirm whether you’re dealing with a capacitor or fan motor failure.
Step 2: Remove Rooftop AC Shroud Cover
Climb onto your Highland Ridge’s roof with proper safety equipment and locate the four to six bolts securing the AC shroud. Carefully lift and set aside the outer cover, noting the position of any wiring connectors and taking photos for reassembly reference.
Step 3: Replace Dual Run Capacitor Unit
Discharge the old capacitor by using an insulated screwdriver to short the terminals together, then unbolt and disconnect the dual run capacitor from its mounting bracket. Install the new Dometic/Coleman-Mach capacitor by reversing the process, ensuring all wire terminals are firmly seated and the capacitor is securely bolted to prevent vibration damage.
Step 4: Service Fan Motor & Coils
Remove the fan blade assembly and inspect the motor shaft for debris or corrosion, cleaning gently with a dry cloth if needed. Apply AC evaporator/condenser coil cleaner foam to the coils following product instructions, and use your fin comb to straighten any bent cooling fins for optimal airflow.
Step 5: Install New Fan Motor Assembly
If your fan motor shows signs of wear or doesn’t spin freely, unbolt the old motor and disconnect its wire harness carefully. Position your new fan motor into the mounting brackets, reconnect the wiring harness with the correct polarity, and tighten all bolts securely.
Step 6: Reseal Rooftop AC Gasket
Remove the old AC roof gasket by peeling it away from the mounting surface and clean any remaining adhesive with rubbing alcohol. Install the new gasket and self-leveling lap sealant around the shroud perimeter, pressing firmly to create a waterproof seal that prevents future leaks.
Step 7: Test AC Cooling & Performance
Turn your RV’s electrical system back on, set the thermostat to cooling mode, and listen for smooth fan operation without rattling or grinding noises. Use your infrared thermometer to verify that cold air is flowing from the vents and compare temperatures before and after service to confirm proper repair completion.
Recommended Parts
| Part | Link |
|---|---|
| RV AC dual run capacitor (Dometic/Coleman-Mach) | View on Amazon |
| Rooftop AC fan motor | View on Amazon |
| RV AC thermostat / control board | View on Amazon |
| AC evaporator/condenser coil cleaner foam | View on Amazon |
| Rooftop AC shroud / outer cover | View on Amazon |
| AC roof gasket & self-leveling lap sealant | View on Amazon |
| Fin comb / coil straightener tool | View on Amazon |
| Non-contact infrared thermometer | View on Amazon |