Complete repair guide for the Tiffin Zephyr – 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 & Gather Tools
Begin by powering on your Tiffin Zephyr’s rooftop AC unit and listen for the compressor cycling and fan motor engagement. If the fan doesn’t spin or the unit runs but produces weak cooling, the capacitor or fan motor has likely failed—capacitors typically last 3–5 years in RVs. Gather your tools: a multimeter set to microfarads (μF) for capacitor testing, a Phillips screwdriver, a 1/4-inch wrench set, and ensure the AC breaker is switched off at your main panel before proceeding.
Step 2: Access the Rooftop AC Unit Safely
Set up a sturdy ladder or roof access system and climb to your RV’s rooftop, ensuring the AC breaker remains off at the main panel for electrical safety. Locate the Dometic or Coleman-Mach AC unit (typically mounted center-roof on Zephyrs) and visually inspect for debris, rust, or visible damage to the shroud. Clear away leaves, dirt, or roof sealant buildup around the unit’s base using a soft brush; this improves airflow and gives you clear access to the shroud fasteners.
Step 3: Remove Shroud & Disconnect Electrical Connectors
Unscrew the four corner bolts securing the rooftop AC shroud (typically 3/8-inch), then carefully lift the outer cover away from the unit to expose the capacitor and fan motor assembly. You’ll see two or three electrical connectors: one thick two-wire connector on the capacitor and one or two connectors on the fan motor itself. Before disconnecting anything, take a photo of the connector positions with your phone, then gently pull each connector straight off—do not twist or force them.
Step 4: Test & Replace the Dual Run Capacitor
Set your multimeter to the capacitance (μF) setting and touch the probes to the two terminals on your existing capacitor; a healthy unit reads 35–50 μF (specs vary by model—check your AC nameplate). If the reading is significantly lower or shows zero, the RV AC dual run capacitor has failed and must be replaced. Unscrew the single bracket bolt holding the old capacitor, slide it free, disconnect its terminals, then position the new capacitor in the bracket, reconnect the terminals with firm pressure, and secure with the bolt—ensure terminals don’t touch the metal housing.
Step 5: Inspect & Replace the Fan Motor Assembly
Spin the fan blade by hand (power is off); it should rotate freely with minimal resistance—if it’s stiff, seized, or doesn’t spin, the bearing is worn and replacement is necessary. Note the motor’s shaft orientation and the position of the single mounting bracket bolt before unbolting the old fan motor from its housing. Install the new RV rooftop AC fan motor by aligning the shaft in the same position, securing the mounting bracket bolt snugly (do not over-tighten), then reconnect its electrical connectors using your photo reference.
Step 6: Clean Coils & Reseal the Shroud
Spray AC evaporator/condenser coil cleaner foam generously over the fins and internal coil surfaces, let it sit for 5–10 minutes, then rinse gently with a low-pressure hose; this removes mineral buildup that restricts airflow. If any fins are bent, use your fin comb / coil straightener tool to gently straighten them in one direction only. Remove the old AC roof gasket completely, clean the mounting surface with a dry cloth, apply the new roof gasket, then reinstall the shroud and tighten all four corner bolts evenly; finish by applying AC roof gasket & self-leveling sealant around the shroud perimeter to prevent leaks.
Step 7: Power Up & Verify Proper Operation
Return to the RV interior, switch the AC breaker back on, set your thermostat to cooling mode at 70°F, and listen for the compressor to start and the rooftop fan to engage within 30 seconds. Use your non-contact infrared thermometer to measure the temperature of the cold-air discharge vent (should read 45–55°F when running) and compare it to the interior temperature; a 20–30°F difference indicates proper cooling performance. Allow the unit to run for 15 minutes, check that the thermostat / control board cycles normally, and confirm no water drips from the roof around the AC—if any issues occur, recheck your electrical connectors and ensure the gasket seated correctly.