Newmar Bay Star – AC Capacitor & Fan Motor Service

Your Newmar Bay Star’s rooftop AC quits pushing cold air mid-July, and you’re already asking yourself: is this a capacitor, a motor, or am I looking at a five-figure compressor replacement? The answer, in most cases, is simpler than that — and it’s something you can fix yourself if you know what you’re looking at. When you’re living full-time on your own power and water, there’s no calling a service department on Monday; the AC either works now or you’re cooking. I’ve pulled apart enough Dometic units mounted on Bay Stars to know exactly where these systems break down, what the actual failure chain looks like, and which parts fail so predictably you should almost expect them. This is the repair I’ve done enough times that I can walk you through it without guessing — real part numbers, real failure modes, and the exact sequence that separates a one-time fix from a repair that leaves you stranded again before Labor Day.

Replacing the Run Capacitor on Your Dometic Rooftop Unit

A run capacitor deteriorates without announcing itself — your fan motor just loses its punch gradually, spinning slower with each passing day until the airflow drops to barely noticeable. By the time you’ve figured out what’s wrong, you’re already sweltering in a rig with no breeze and nowhere to escape the heat.

Where this repair succeeds

• Fan motor snaps back to normal operation instantly — that urgent, high-pitched whir returns the moment you restore power, a completely different sound from the weak churn you’ve been hearing.
• System cooling performance gets back to spec almost immediately; your compressor no longer has to strain against a fan that’s barely turning over.
• Bolt-in compatibility with 3312195.000 models means zero adapter searching, zero “maybe this will fit” uncertainty while you’re sweating on the roof in the middle of summer.

Where it stumbles

• Standard shipping through the major retailers runs 5–7 days minimum; when your capacitor fails in peak heat season, that waiting period feels endless and you’re already desperate.
• You absolutely must discharge the old capacitor before touching it — failing to do this will send voltage through you that can stop your heart; if you don’t have a meter and know how to use it, hire someone who does.

I second-guessed the spec number the first time I ordered one, convinced I had the wrong digits from the manual, but the 60/5 MFD rating was exactly right and the part dropped in without modification. 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

Parts and Tools

• Replacement dual run capacitor matched to the microfarad and voltage rating on the old one (typically 60/5 MFD for Dometic rooftop units on Bay Stars) — check current price
• Needle-nose pliers or small adjustable wrench for terminal connections
• Insulated screwdriver set (flathead and Phillips) for access panel and terminal screws
• Multimeter with capacitance setting to verify the old capacitor’s failure
• Electrical tape or heat shrink tubing for insulating exposed terminals
• Discharge tool or insulated jumper wire to safely bleed residual charge from the old capacitor

Step-by-Step Instructions

Step 1: Kill power to the AC unit at the breaker

Locate your Bay Star’s main electrical panel and flip the breaker controlling the rooftop AC to the OFF position. Wait five minutes. Even with the breaker off, capacitors hold a charge—do not skip this step or you risk a shock that will drop you off the ladder. Take a photo of the breaker panel with the AC breaker clearly labeled so you remember which one it is.

Step 2: Access the rooftop unit and locate the capacitor

Climb to the roof using a stable ladder and secure yourself. Remove the AC shroud cover (usually four to six bolts around the perimeter). The capacitor sits near the fan motor, typically a cylindrical aluminum or plastic component with two or three wire terminals protruding from the top. It’s roughly the size of a D battery. Photograph the exact terminal positions and wire colors before touching anything.

Step 3: Discharge the capacitor safely

Using an insulated screwdriver or discharge tool, touch the blade across both terminals simultaneously to bleed any residual charge. You may see a small spark—this is normal and expected. Wait ten seconds, then repeat the process. This prevents a shock when you disconnect the wires. Do not skip this step even though the breaker is off.

Step 4: Test the old capacitor with a multimeter

Set your multimeter to capacitance mode. Touch the probes to the two main terminals on the capacitor. A healthy capacitor reads close to its rated microfarad value (60 MFD for most Bay Star units). If the reading is zero, significantly lower than rated, or the meter shows an error, the capacitor has failed. Document this reading—it confirms the diagnosis before you remove anything.

Step 5: Disconnect the old capacitor terminals

Using needle-nose pliers or a small wrench, loosen the terminal nuts one at a time and slide the wire connectors off. Keep the wires separated so they don’t touch each other or the metal housing. Set the old capacitor aside. Do not let the disconnected wires touch the AC frame or each other, as this can create a short when power is restored.

Step 6: Install the new capacitor and reconnect terminals

Position the new capacitor in the same location as the old one, ensuring it sits firmly and does not contact any moving fan blades or sharp edges. Slide the wire connectors onto the corresponding terminals—match wire colors to the terminals they came from. Tighten each terminal nut firmly with pliers, but do not over-tighten; you want a solid connection without stripping the threads.

Step 7: Reassemble the unit and restore power

Replace the AC shroud cover and secure all bolts. Climb down from the roof and return to the breaker panel. Flip the AC breaker back to ON. Listen for the fan motor—it should spin up with a sharp, urgent whir and sound noticeably stronger than before. Feel the air output at the vents; airflow should be immediate and robust. If the fan does not spin or sounds weak, turn the breaker off immediately and recheck your terminal connections.

Step 8: Verify cooling performance over 30 minutes

Set your thermostat to cool mode and allow the system to run for at least 30 minutes. Check the interior temperature drop and listen for the compressor cycling normally. The cabin should cool noticeably faster than it did before the repair. If the system cycles on and off rapidly or fails to cool, the capacitor may have been a symptom of a larger motor or compressor issue—stop and reassess.