Forest River Cedar Creek – AC Capacitor & Fan Motor Service

Hey there, I’m Drew Callahan. After traveling over 80,000 miles across North America in three different rigs, I’ve learned a thing or two about keeping my gear in top shape. It was late July, and the thermometer hit 105 degrees somewhere outside Barstow — not exactly the ideal spot to have your AC quit on you. I was three weeks into a trip down the California coast in my Cedar Creek, which I had owned for about eighteen months. That rooftop unit had been acting up since dawn: the compressor would kick in, struggle for about ten seconds, and then trip the breaker. The fan motor sounded like marbles rattling inside a tin can. Sitting under the awning, sweating through my shirt, I realized I had encountered this exact failure pattern twice before on my other rigs. Ninety percent of the time, that noise-and-stall combo indicates a run capacitor on its way out, combined with a fan motor bearing that’s been running dry for too long. Fix it quickly — before the system overheats into complete shutdown — and you can be running cold again in under an hour. Ignore it or misdiagnose it, and you’re facing a new condenser assembly, a four-figure repair bill, or worse, a rig you end up selling at a loss to someone who actually knows what to listen for.

Understanding the Dual Run Capacitor in Cedar Creek AC Systems

Your compressor and condenser fan need to work in sync — and that’s where the capacitor comes into play. When it fails, the compressor engages but the fan remains motionless, drawing maximum current while providing zero cooling and ultimately overheating itself into a shutdown cycle. On Cedar Creek models, this is the most common AC failure, and it makes its presence known quickly and loudly.

Parts and Tools

• Replacement dual run capacitor matched to the microfarad and voltage rating on the old one (typically 45+5 µF at 370V for Cedar Creek rooftop units) — check current price
• Needle-nose pliers or small adjustable wrench for terminal connections
• Multimeter with capacitance setting to verify the old capacitor’s condition before removal
• Insulated screwdriver set (flathead and Phillips) for access panel and terminal work
• Electrical tape or heat-shrink tubing to secure and insulate any exposed wire connections
• Small container or labeled bag to keep fasteners organized during disassembly

Step-by-Step Instructions

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

Locate your main electrical panel and flip the breaker serving the AC unit to OFF. Wait thirty seconds, then use a multimeter set to AC voltage to confirm zero volts at the unit’s power terminals. This prevents shock and protects the compressor from a hot-start surge while you work. Do not skip this step—capacitors store charge even after power is cut.

Step 2: Access the capacitor mounting location

Climb onto the roof and locate the rooftop AC unit. The access panel is typically on the side or rear of the condenser box, held by two to four Phillips-head screws. Remove these screws and set them aside in a labeled container. Photograph the wire routing and terminal positions before disconnecting anything—this prevents confusion during reassembly.

Step 3: Test the old capacitor and document its rating

Set your multimeter to capacitance mode and touch the probes to the capacitor terminals. A reading significantly below the marked microfarad value (or an open-circuit reading) confirms failure. Write down the exact microfarad and voltage rating printed on the capacitor’s label—this ensures you buy the correct replacement. A failed capacitor typically reads zero or shows infinite resistance.

Step 4: Discharge the capacitor safely

Even with power off, a capacitor holds residual charge. Use an insulated screwdriver to short the two terminals together briefly, then touch each terminal to ground (the metal housing). This bleeds any remaining voltage harmlessly. Wait five seconds before proceeding to avoid a shock or spark.

Step 5: Remove the old capacitor and disconnect terminals

Using needle-nose pliers, gently pull the spade terminals off the capacitor posts. If terminals are corroded or stuck, apply a small amount of penetrating oil and wait two minutes. Note which wire (usually marked with a dot or stripe) connects to which terminal—take a photo if needed. Unscrew or unclip the capacitor mounting bracket and remove the old unit.

Step 6: Install the new capacitor and reconnect terminals

Mount the new capacitor in the same bracket using the original fasteners, ensuring it sits firmly and level. Reconnect the spade terminals to their original posts—match the marked wire to the marked terminal. Crimp or tighten each connection firmly; a loose terminal will cause the same failure pattern within weeks. Double-check polarity if the capacitor has a polarity marking.

Step 7: Reassemble the access panel and test the unit

Replace the access panel screws and tighten them snugly without over-torquing. Climb down, return to the breaker panel, and flip the AC breaker back to ON. Listen for the compressor to engage smoothly and the fan to spin immediately without grinding or hesitation. The unit should cycle normally and begin cooling within two minutes. If the compressor still trips the breaker, stop immediately and recheck terminal connections.

What Works

• Both motors — the compressor and condenser fan — start spinning simultaneously, instead of the compressor struggling while the fan stays locked.
• Cold air starts flowing from your vents within ten minutes, not the weak, barely-cool trickle that a failing capacitor delivers.
• The entire job — taking out the old parts, putting in the new ones, and testing everything — takes about fifteen minutes on the roof with just a socket wrench and a screwdriver.

What Doesn’t Work

• Third-party sellers online often offer generic substitutes labeled as Dometic/Coleman-Mach compatible that fit but have the wrong microfarad specification for your unit.
• Installing a capacitor rated at the wrong microfarads — even if you’re off by just 5µF — can leave the fan dead, making you think the part is faulty when really it’s just not the right size for the job.

At one point, I almost ordered a generic 40µF capacitor from eBay because it was cheaper and showed up faster. But the original on that Cedar Creek was dual-rated at 40/5µF, and a single capacitor would have led to a week of troubleshooting with the fan still not working. RV AC dual run capacitor (Dometic/Coleman-Mach)

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