Newmar Bay Star Sport – AC Capacitor & Fan Motor Service

Newmar Bay Star Sport – AC Capacitor & Fan Motor Service

by

Complete repair guide for the Newmar Bay Star Sport – 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 Issues

Start by running your Bay Star Sport’s AC system for 10-15 minutes and use the non-contact infrared thermometer to measure the temperature of the air coming from the vents—you’re looking for readings between 40-50°F for proper cooling. Listen for unusual humming, rattling, or grinding sounds from the rooftop unit, and check whether the fan motor is running at all; if the compressor cycles on but the fan doesn’t spin, or if the unit produces weak airflow despite running, you likely have a failed capacitor or fan motor. Turn off the AC breaker and visually inspect the rooftop unit from ground level using binoculars, noting any visible corrosion, refrigerant leaks (oily residue around fittings), or damaged fins on the condenser coil.

Step 2: Prepare Unit and Disconnect Power

Switch off the AC circuit breaker at your main electrical panel and verify the power is off by attempting to operate the thermostat—the unit should not respond. Locate the rooftop access point on your Bay Star Sport and set up a stable ladder or roof access platform; you’ll need secure footing to safely work on the AC unit for 30-45 minutes. Allow the unit to cool for at least 20 minutes after shutting down to avoid burns from hot refrigerant lines or compressor components.

Step 3: Remove Shroud and Inspect Components

Unbolt the rooftop AC shroud/outer cover by removing the four corner fasteners (typically 3/8-inch bolts) and carefully lift it away, noting the position of any wiring harnesses attached to the fan motor. Once exposed, visually inspect the RV AC dual run capacitor—a cylindrical component usually mounted near the compressor—for signs of failure: bulging top, leaking electrolyte (oily residue), or a burnt smell. Take a photo of the capacitor’s rating label (you’ll see microfarad ratings like 35+5 µF or similar) and note the voltage rating before disconnecting anything.

Step 4: Disconnect and Test the Capacitor

Using an insulated screwdriver, carefully discharge the capacitor by touching the blade across both terminals to release any stored electrical charge—this step is critical for safety. Disconnect the two wire terminals from the capacitor by loosening the terminal nuts with a socket wrench, then remove the mounting bracket bolt to free the component completely. Before installing the new RV AC dual run capacitor, confirm its rating matches your removed unit exactly; mismatched capacitors will prevent proper motor starting and can damage the compressor.

Step 5: Install New Capacitor and Fan Motor

Mount the new capacitor in the original bracket using the same bolt, ensuring it’s positioned away from hot refrigerant lines and the compressor discharge tube. Connect the two terminals firmly, tightening them until snug (don’t over-torque, as the terminal posts can crack); use the fin comb tool to straighten any bent condenser fins while you have clear access to improve airflow efficiency. If the fan motor is also failing (indicated by no blade rotation even with new capacitor), unbolt the motor assembly, disconnect its wiring harness, and install the new RV rooftop AC fan motor, ensuring the blade spins freely by hand before final assembly.

Step 6: Reseal and Reinstall Shroud Cover

Apply a continuous bead of AC roof gasket & self-leveling sealant around the bottom edge of the rooftop AC shroud where it meets the unit’s housing—this prevents water intrusion and maintains cooling efficiency. Carefully lower the shroud back into place, align the corner bolt holes, and hand-tighten all four fasteners before using a socket wrench to bring them to a firm, even tension (avoid over-tightening, which can crack the shroud). Allow the sealant to cure for 24 hours before running the AC system.

Step 7: Test System Performance and Verify Operation

Restore power at the breaker and set your thermostat to cool mode, listening for the compressor to engage followed immediately by the fan motor spinning (the fan should run smoothly without grinding or rattling). Use the non-contact infrared thermometer to measure return air temperature at the thermostat and outlet air temperature at a ceiling vent after 10 minutes of operation—you should see a temperature drop of 15-20°F between them, indicating proper cooling capacity. Run the system for 20 minutes and confirm that the unit cycles on and off at appropriate intervals; if the compressor runs continuously without reaching set temperature or the fan doesn’t engage with the new capacitor, you may have additional refrigerant loss requiring professional service.