Newmar Bay Star – AC Capacitor & Fan Motor Service

Newmar Bay Star – AC Capacitor & Fan Motor Service

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Complete repair guide for the Newmar Bay Star – AC Capacitor & Fan Motor Service. Follow these steps to diagnose and fix the issue yourself.

Parts & Tools You’ll Need

Step 1: Diagnose AC Performance & Safety Check

Start by running your Bay Star’s AC system for 10-15 minutes and note any symptoms: weak cooling, unusual grinding noises, or the compressor cycling on and off rapidly. Use your non-contact infrared thermometer to measure the temperature at the AC outlet—it should read between 50-60°F when the thermostat is set to maximum cooling. Before proceeding, turn off power at your RV’s main breaker and verify the system is de-energized using a multimeter set to AC voltage mode on the capacitor terminals.

Step 2: Access Rooftop AC Unit & Remove Shroud

Climb onto your RV’s roof and locate the Newmar Bay Star’s AC unit, which is typically mounted toward the front section. Unbolt the rooftop AC shroud using a Phillips or flathead screwdriver (usually 6-8 bolts around the perimeter), then carefully lift it straight up to expose the internal components. Inspect and photograph the internal layout to aid reassembly, noting the wire routing and bolt positions.

Step 3: Discharge Capacitor & Disconnect Power

Even with the breaker off, discharge the RV AC dual run capacitor by using an insulated screwdriver to create a short circuit between each terminal pair for 3-5 seconds—you may hear a small pop or see a spark, which is normal. Once discharged, use a multimeter to confirm 0V across the capacitor terminals. Disconnect the two or three wire connectors from the old capacitor (noting their positions) and unscrew the mounting bracket bolt.

Step 4: Install New Dual Run Capacitor

Position your new RV AC dual run capacitor (typically rated 45+5 microfarads at 370V for Dometic or Coleman-Mach units) in the same mounting location and secure it with the bracket bolt—ensure it’s snug but not over-tightened. Reconnect the wire terminals in the exact same configuration as the original, double-checking that each connector is fully seated and secure. Verify the capacitor’s microfarad and voltage ratings match your AC unit’s specifications, which are usually printed on the compressor housing.

Step 5: Replace Fan Motor & Check Bearings

Locate the rooftop AC fan motor (usually a 1/4 to 1/3 HP unit) and disconnect its power harness by gently pulling the connector straight out. Remove the mounting bolts (typically 3-4 bolts) and lift the old motor away, noting its orientation. Install your new RV rooftop AC fan motor in the reverse sequence, ensuring the motor shaft spins freely by hand before reconnecting the harness—it should rotate with minimal resistance and no grinding sounds.

Step 6: Clean Coils & Reseal Unit Housing

Spray your AC evaporator/condenser coil cleaner foam across the aluminum fins and allow it to sit for 5-10 minutes, then rinse thoroughly with a low-pressure water source or compressed air—avoid high-pressure spray that may bend the fins. Use your fin comb tool to straighten any bent fins, working gently from the base outward at a 45-degree angle. Apply a bead of AC roof gasket sealant and self-leveling sealant around the shroud mounting surface before reinstalling, then bolt the rooftop AC shroud down securely.

Step 7: Test System & Verify Cooling Performance

Restore power at your RV’s main breaker and set the thermostat to cool mode at maximum setting, allowing the system to run for 15-20 minutes. Check the AC outlet temperature again with your non-contact infrared thermometer—you should see 50-60°F airflow and hear the fan motor running smoothly without vibration or noise. Verify that the compressor engages within 2-3 minutes and that the interior temperature drops noticeably; if cooling is weak or the motor doesn’t engage, recheck all wire connections and capacitor terminals for loose contacts.