Complete repair guide for the Nexus Triumph – AC Capacitor & Fan Motor Service. Follow these steps to diagnose and fix the issue yourself.
Parts & Tools You’ll Need
- Fits for Dometic 3312195.000 Air Conditioner RV AC Motor Capacitor 60/5 MFD, Heavy Duty Air Conditioner Capacitor Replacement, Compatible with Dometic 3312195000 RV Air Conditioner Models — RV AC dual run capacitor (for Dometic or Coleman-Mach)
- HHQ RV Air Conditioner Motor with Capacitor, Direct Replacement for Coleman Mach RV AC Fan Motor, Replaces Fasco D1092, 1/3 HP, 115 Volts, 1675 RPM, 5-Year Warranty — RV rooftop AC fan motor
- 3106996022 3106996.022 Heat & Cool Thermostat Relay Analog Control Circuit Board Kit for Dometic RV Air Conditioner (White) — RV AC thermostat / control board
- CRC (05084-12PK) Brakleen Non-Chlorinated Brake Parts Cleaner – 14 oz., (Pack of 12) — AC evaporator/condenser coil cleaner foam
- LEDBarz RV Air Conditioner Shroud Cover Screws (10 Pack) for Dometic RV Brisk II and Penguin II Roof Top Air Conditioner, Replacement Parts for Dometic 3310724.0040000002 — Rooftop AC shroud / outer cover
- Dongxw Self Leveling RV Roof Sealant White, 4 Pack Camper Roof Sealant, Lap Sealants for RVs Roofs, Waterproof Flexible RVs Sealants and Caulk for Trailer, Maintenance, Repair — AC roof gasket & self-leveling sealant
- AMI PARTS FCR6 Fin Comb Set for Air Conditioner FCR6 Coil Fin Comb Ring Straighten Evaporator Condensor — Fin comb / coil straightener tool
- FKM Infrared Thermometer Gun Non-Contact Laser Temperature Gun,-58°F~986°F(-50°C~530°C) AdjustableEmissivity,Digital Thermometer Gun for Industrial,Kitchen Cooking,Oven,Automotive,HVAC,Not for Human — Non-contact infrared thermometer
Step 1: Diagnose AC Failure & Disconnect Power
Before touching any components, switch off your RV’s electrical breaker dedicated to the rooftop AC unit—typically a 30 or 50-amp circuit depending on your system. Use a non-contact infrared thermometer to measure the temperature difference between the air entering and exiting your AC unit; a difference of less than 15°F indicates a failed capacitor or fan motor. Listen for a humming sound without the fan spinning (capacitor failure) or complete silence (motor failure), then visually inspect the dual run capacitor for bulging, leaking, or a burnt smell around the unit.
Step 2: Remove Rooftop AC Shroud Safely
Climb onto your RV roof using proper fall protection and locate the four to six bolts securing the rooftop AC shroud/outer cover—these are typically 3/8-inch or 1/2-inch fasteners. Carefully unbolt and lift away the shroud, noting the position of any wiring harnesses connected to the thermostat/control board before fully removing it. Set the shroud on a clean, flat surface to avoid damage and keep all fasteners in a labeled container.
Step 3: Test & Replace the Dual Run Capacitor
Locate the dual run capacitor (typically rated 35/5 microfarads at 440 volts for Dometic or Coleman-Mach units) mounted near the compressor or fan motor. Using a multimeter set to capacitance mode, test the capacitor’s output; readings significantly below the rated microfarad value confirm failure. Before disconnecting, use a screwdriver to safely discharge any residual electrical charge by bridging the terminals, then unbolt and remove the failed capacitor. Install the replacement RV AC dual run capacitor by connecting the common wire (C), herm wire (H), and fan wire (F) to their corresponding terminals, ensuring all connections are tight.
Step 4: Inspect & Clean the Fan Motor Assembly
Spin the rooftop AC fan motor blade by hand; it should rotate freely without grinding sounds or excessive resistance. If the motor is stuck or making noise, check for debris, ice buildup, or corrosion around the shaft and bearing—use a fin comb/coil straightener tool to gently clear any blockages. Apply AC evaporator/condenser coil cleaner foam to the fan motor housing and the surrounding condenser coil, following product instructions for dwell time and rinsing with distilled water.
Step 5: Replace the Fan Motor if Necessary
If the fan motor fails the spin test or shows no electrical continuity when tested with a multimeter, unbolt it from its mounting brackets (typically two to four bolts). Disconnect the motor’s wire harness from the thermostat/control board by carefully removing the spade terminals. Install the replacement RV rooftop AC fan motor by reversing the removal process, ensuring the motor shaft aligns with the fan blade hub and all bolts are torqued to 12-15 foot-pounds.
Step 6: Reseal Unit & Reinstall Shroud Cover
Inspect the AC roof gasket for cracks, hardening, or missing sections that could allow water infiltration—replace it if any damage is visible. Apply a bead of self-leveling sealant around the gasket perimeter and the shroud bolt holes, then carefully lower the rooftop AC shroud back into place and hand-tighten all bolts before using a wrench to snug them evenly to prevent warping. Wipe away excess sealant with a damp cloth and allow 24 hours of curing time before exposing the unit to rain.
Step 7: Test System Performance & Verify Cooling
Restore power at the breaker and set your RV AC thermostat/control board to cooling mode at 72°F, listening for the compressor and fan motor to engage within 30 seconds. Using the non-contact infrared thermometer, measure the temperature of air exiting the AC vents after 15 minutes of operation—the temperature should be 15–20°F cooler than the ambient air entering the unit. Check that the dual run capacitor shows no signs of bulging or overheating (touch-test the shroud after 30 minutes of operation; it should be warm but not hot enough to burn your hand), and verify that all roof fasteners remain tight and the sealant has cured properly.