The most expensive mistake RV owners make is replacing parts before they’ve diagnosed the actual problem. I’ve walked up to rigs where the owner has already swapped three components and the real issue is something a five-dollar fuse or a loose connector would have fixed. Diagnosis first. Always diagnosis first. On the Brinkley Model Z, the AC system is one of the first things owners panic about — and understandably so, because when your rooftop unit stops cooling in the middle of July, comfort disappears fast and food and medications can be at risk. Most of the time, what looks like a dead compressor or a failed control board traces back to a weak run capacitor or a seized fan motor — two components that are absolutely serviceable roadside with the right know-how — and that’s exactly what this guide is built to walk you through, step by step, the way I’d talk you through it standing right there beside your rig.
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 Issues and Ensure Safety
Begin by turning off your RV’s main electrical breaker and the AC unit itself to prevent electrical shock during diagnosis. Use your non-contact infrared thermometer to check the temperature differential between the inlet and outlet air to confirm whether the capacitor or fan motor is faulty—a weak temperature difference typically indicates motor or capacitor failure.
Step 2: Remove Rooftop AC Shroud Cover
Climb onto your RV roof safely and locate the four corner bolts securing the outer shroud. Carefully lift and remove the shroud to expose the internal AC components, taking note of the wire connections to the fan motor and capacitor for reassembly.
Step 3: Replace Dual Run Capacitor Unit
Disconnect the wire terminals from the old capacitor using a small screwdriver, then unbolt the mounting bracket and lift out the failed unit. Install your new Dometic or Coleman-Mach dual run capacitor in the same orientation, reconnecting the three terminal wires (common, herm, and fan) in their original positions.
Step 4: Service Fan Motor and Coils
Inspect the fan motor for debris and corrosion, then spray the evaporator and condenser coils with AC coil cleaner foam according to product instructions. Use your fin comb tool to straighten any bent aluminum fins on the coils, which will improve airflow and cooling efficiency significantly.
Step 5: Install New Fan Motor Assembly
Remove the three bolts securing the old motor to the fan blade assembly and disconnect its electrical wires. Position your new rooftop AC fan motor in alignment with the blade hub, secure it with bolts, and reconnect the wires to the capacitor terminals and control board.
Step 6: Seal and Reassemble Roof Components
Apply a bead of self-leveling lap sealant around the shroud opening and install a new AC roof gasket to prevent water infiltration. Carefully lower the shroud back into place, align the bolt holes, and tighten all four corner bolts evenly to create a watertight seal.
Step 7: Test AC Performance and Monitor Operation
Restore power to your RV’s electrical system and turn on the AC unit, listening for smooth fan motor operation and feeling for cold air output. Allow the system to run for 15-20 minutes while monitoring the inlet and outlet temperatures with your infrared thermometer to confirm proper cooling function.
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 |