Crossroads Redwood – AC Capacitor & Fan Motor Service

I’m Drew Callahan, and as someone who’s racked up over 80,000 miles across North America in three different rigs, I know the importance of a reliable AC unit. Right now, my Crossroads Redwood is parked in a pull-through site, and I’m looking up at the rooftop AC unit—the same one that has kept me cool through scorching Arizona summers and sticky coastal humidity. When it works, it’s like magic. But when the capacitor fails, you feel the consequences almost immediately: the compressor is humming, but the fan is barely moving, and before long, the interior is heating up to uncomfortable levels. The worst part? Ignoring a simple issue like a failed run capacitor or seized fan motor can lead to a burned-out compressor, transforming a twenty-dollar fix into a four-hundred-dollar disaster. In this post, I’ll guide you through diagnosing the problem, swapping out the part, and handling this repair yourself—especially useful when you’re stuck somewhere remote without easy access to a dealer service bay. I’ve done this repair in my driveway, battled through roadside dust storms, and even tackled it under a Walmart awning at dawn before the temperature made it unbearable.

The Run Capacitor: Why Your AC Compressor Hums But Won’t Turn

In my experience with Crossroads Redwoods, a dead or failing run capacitor is usually the issue when the compressor sounds like it’s trying to start but just can’t get going—and it’s one of the quickest repairs you can make before the motor itself burns out. The dual-run capacitor powers both the compressor and the fan circuit, so when one goes down, it impacts the entire cooling system.

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 Dometic/Coleman-Mach units) — check current price
• Needle-nose pliers or small wire strippers for disconnecting spade terminals
• Multimeter with capacitance setting to test the old capacitor before removal
• Insulated screwdriver set (Phillips and flathead) for opening the AC shroud and accessing terminals
• Replacement fan motor if the existing motor is seized or won’t spin freely by hand after capacitor swap
• Masking tape and marker for labeling wire positions before disconnection

Step-by-Step Instructions

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

Locate your RV’s main electrical panel and switch off the 120V breaker feeding the rooftop AC. Wait five minutes to allow any residual charge to dissipate. This is non-negotiable—capacitors can hold a dangerous charge even when power is off. Double-check that the thermostat is set to off and that no one can accidentally turn the AC back on while you’re working.

Step 2: Access the AC shroud and photograph the wire layout

Climb onto the roof using a ladder and safety harness. Locate the Dometic/Coleman-Mach unit’s access panel—usually held by four Phillips screws around the perimeter. Before removing any wires, take a clear photo of the spade terminal connections on the capacitor. This photo is your insurance against mixing up the compressor and fan leads, which will prevent the unit from running correctly.

Step 3: Test the capacitor with a multimeter

Set your multimeter to capacitance mode. Touch the probes to the two terminals on the capacitor. A healthy capacitor should read close to its rated microfarads (typically 45 µF for the main terminal). If it reads zero, significantly lower, or shows an open circuit, the capacitor is dead. If it reads normal but the fan still won’t spin, the motor itself may be seized—proceed to step five.

Step 4: Disconnect the old capacitor and remove it

Using needle-nose pliers, gently pull each spade terminal off the capacitor posts. If the terminals are corroded or stuck, wiggle gently rather than yanking—you don’t want to damage the posts. Once free, note which wire came from which terminal (your photo helps here). Unscrew the capacitor’s mounting bracket and lift it out. Set it aside safely away from the edge of the roof.

Step 5: Install the new capacitor and reconnect wires

Position the new capacitor in the same mounting location and secure it with the bracket screw. Match the wire terminals to the correct posts using your photograph—compressor lead to one post, fan lead to the other. Slide each spade terminal firmly onto its post until it seats completely. Tug gently on each wire to confirm the connection is solid and won’t slip off during vibration.

Step 6: Manually spin the fan blade to check for seizure

Before restoring power, reach into the AC shroud and try to rotate the fan blade by hand. It should turn freely with minimal resistance. If it’s stuck or grinding, the motor is seized and needs replacement—do not power on the unit. If it spins freely, you’re ready to test. Replace the shroud and tighten all screws.

Step 7: Restore power and verify operation

Climb down from the roof and switch the AC breaker back on. Set the thermostat to cool and listen for the compressor to start. Within a few seconds, the fan should spin at full speed and you should hear air moving through the vents. Feel the air coming from the interior vents—it should be noticeably cooler than ambient temperature within two minutes. If the compressor hums but the fan doesn’t spin, the motor is bad and needs replacement.

What works

• Once you swap the capacitor, the compressor should engage on the first spin—no more of that dead-hum stall.
• The fan motor will ramp back up to its rated speed instead of that sluggish crawl that leaves your interior feeling stuffy.
• It’s a bolt-and-clip swap on Dometic and Coleman-Mach units—straight terminal connection means no harness rewiring or adapters are needed.

What doesn’t

• For Redwoods built in 2010 and earlier, the microfarad specs can differ between model runs—make sure to double-check the MFD rating on your unit’s nameplate before purchasing. Using the wrong capacitor value can choke the compressor or prevent it from starting altogether.
• Online retailers might take a week to deliver; if you’re sweltering in 115-degree heat and need this part ASAP, reach out to an independent HVAC supplier (not an RV dealership parts counter). They usually have stock available at a comparable price and can have it ready for you within hours.

I remember swapping one out for a customer’s Redwood in a Walmart parking lot in Arizona. I held my breath for those first 30 seconds—silence instead of the usual hum made me think I had installed a faulty unit until the compressor finally clicked into action. Be sure to grab the RV AC dual run capacitor (Dometic/Coleman-Mach) and confirm your unit’s uF rating before you check out.

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