Coachmen Mirada – AC Capacitor & Fan Motor ServiceSave

Coachmen Mirada – AC Capacitor & Fan Motor Service

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The full-time RV community is the most generous knowledge-sharing group I’ve ever been part of. Someone has already fixed the exact problem you’re dealing with, documented it in a forum thread, and answered follow-up questions for free. This guide pulls together the best of that collective experience into one place. When your Coachmen Mirada’s AC unit starts humming but won’t cool — or the fan blade just sits there spinning weakly before giving up — a failed run capacitor or fan motor is almost always the culprit, and in a rig you live in full-time, a dead air conditioner isn’t a weekend inconvenience, it’s a genuine health and safety problem. The good news is that these are among the most approachable repairs you can tackle yourself: the parts are inexpensive, the process is logical, and every step here has been tested by real owners who were in the exact same sweaty, frustrated spot you’re in right now.

Parts & Tools You’ll Need

Step 1: Diagnose AC Failure & Prepare Workspace

Start by running your Mirada’s AC system and listening for the compressor cycling on—if you hear the compressor but the fan won’t spin, you’ve likely got a capacitor or motor issue. Turn off all power at the main breaker and let the rooftop unit sit for 5-10 minutes to discharge any residual electrical current before touching internal components. Gather your parts, tools, and a clear workspace on the roof, ensuring you have safe ladder access and stable footing.

Step 2: Remove Rooftop AC Shroud & Access Interior

Unbolt the rooftop AC shroud/outer cover using a 10mm socket or wrench; typically there are 4-6 fasteners around the perimeter—keep these bolts organized. Carefully lift the shroud away to expose the fan motor, capacitor, and internal wiring without crimping any refrigerant lines or control wires. Take a photo of the wire harness connections before disconnecting anything, as this will serve as your reference during reassembly.

Step 3: Test & Replace the Dual Run Capacitor

Locate the cylindrical dual run capacitor (usually rated 35+5 microfarads or similar) mounted near the fan motor housing. Using a capacitor discharge tool or an insulated screwdriver, short the capacitor terminals together to safely discharge any remaining energy—this prevents electrical shock. Disconnect the two spade terminals and note their positions, then install your new RV AC dual run capacitor for Dometic or Coleman-Mach (depending on your unit’s brand) by reversing the process, ensuring terminals are fully seated.

Step 4: Inspect & Clean Evaporator/Condenser Coils

While the shroud is off, spray the AC evaporator/condenser coil cleaner foam across the aluminum fins and coil surfaces, allowing it to soak for 3-5 minutes per the product instructions. Use a soft brush or the fin comb/coil straightener tool to gently straighten any bent fins and remove debris buildup—bent fins restrict airflow and reduce cooling efficiency by up to 15%. Rinse thoroughly with a garden hose using low pressure, directing water downward away from the electrical components.

Step 5: Remove & Test the Fan Motor Assembly

Unbolt the fan motor (typically 3-4 fasteners) and carefully disconnect its wire harness by pressing the release tab on the connector. Before discarding the old motor, confirm it’s the fault by manually spinning the shaft—a seized or extremely stiff motor indicates bearing failure rather than a capacitor issue alone. Install your new RV rooftop AC fan motor by reversing removal steps, ensuring the shaft spins freely by hand and the motor sits flush against its mounting bracket.

Step 6: Reinstall Shroud & Seal Gasket Properly

Before reinstalling the rooftop AC shroud, inspect the AC roof gasket for cracks or hardening; replace it if it shows significant deterioration to prevent water leaks. Apply a thin, continuous bead of self-leveling sealant along the gasket seating surface, then lower the shroud carefully and torque the fasteners in a crisscross pattern to 8-12 foot-pounds—over-tightening can crack the plastic shroud. Allow the sealant to cure for 24 hours before running the AC system or exposing the roof unit to rain.

Step 7: Power On & Verify Full System Operation

Restore power at the main breaker and set your RV AC thermostat/control board to cooling mode at 72°F; the fan should start within 10-15 seconds and run smoothly without grinding or unusual vibration. Using a non-contact infrared thermometer, measure the cold air discharge temperature at the interior vents—you should see a drop of 15-25°F from ambient room temperature within 5 minutes, indicating the compressor and cooling cycle are functioning properly. Monitor the system for 30 minutes to confirm stable operation, then inspect the rooftop gasket area and all interior vents for any signs of leaks or unusual noise.