Forest River Riverstone – AC Capacitor & Fan Motor Service

As someone who’s traveled over 80,000 miles across North America in three different rigs, I’ve learned a thing or two about RV maintenance. Most RV owners, including myself at times, often walk away from their AC unit thinking it’s either going to work or it’s going to die—there’s no in-between. What I’ve discovered is that a small, inexpensive component inside that rooftop box can fail in ways that *mimic* a complete system breakdown. This can lead to wasting hundreds of dollars and days of troubleshooting before anyone realizes what actually went wrong. On a Forest River Riverstone, the run capacitor is exactly that part. I’ve seen countless owners spend money chasing phantom refrigerant leaks and compressor failures when the real culprit was right there, begging for replacement. Here’s the kicker: if you ignore a weakening capacitor, it will drag your fan motor down with it—a $20 solution can quickly turn into a $300 nightmare.

The Dual Run Capacitor: Why Your Compressor Won’t Engage on Riverstone Units

When a dual run capacitor gives up, I’ve noticed that your AC compressor may spin the fan but never actually engage the cooling cycle—or it hums frantically without any real operation. Forest River Riverstones see this failure more regularly than you might think, and owners often mistake it for a refrigerant shortage or a seized compressor, which is completely backward.

Parts and Tools

• Replacement dual run capacitor matched to the microfarad and voltage rating on the old one (typically 40+5 µF at 370V for Riverstone units) — check current price
• Needle-nose pliers or small wire strippers for disconnecting capacitor terminals
• Multimeter with capacitance setting to test the old capacitor before removal
• Insulated screwdriver set for accessing the AC control box and securing new capacitor
• Discharge tool or jumper wire to safely bleed residual charge from the old capacitor
• Camera or phone to photograph wire positions and terminal connections before disconnecting

Step-by-Step Instructions

Step 1: Kill power to the rooftop AC unit

Switch off the AC breaker at your Riverstone’s main panel and verify it’s off by attempting to power the unit—nothing should happen. Wait 30 seconds for any residual charge to bleed. This prevents shock and protects the compressor circuit. Do not skip this step; capacitors hold voltage even when the breaker is off.

Step 2: Locate and photograph the capacitor assembly

Open the AC access panel on your roof (usually a plastic cover held by two or three screws on the Riverstone’s rooftop unit). Inside, you’ll see the capacitor mounted vertically or horizontally near the compressor motor. Take clear photos of the wire connections—which terminal connects to which wire—before touching anything. This prevents reconnection errors.

Step 3: Test the capacitor to confirm failure

Set your multimeter to capacitance mode. Touch the probes to the capacitor terminals and note the reading. A healthy capacitor reads within 10% of its rated value (printed on the case). If it reads zero, significantly lower, or the meter shows infinity, the capacitor has failed. This confirms the problem before you remove anything.

Step 4: Safely discharge the old capacitor

Using an insulated screwdriver or a dedicated discharge tool, short the two terminals together for 2–3 seconds. You may see a small spark; this is normal and means residual charge is bleeding off safely. This step prevents accidental shock when you disconnect the wires.

Step 5: Disconnect and remove the failed capacitor

Using needle-nose pliers, gently pull each wire terminal off the capacitor posts. Note which wire came from which terminal (your photo helps here). Unscrew or unclip the capacitor mounting bracket and remove the old unit. Do not force the terminals; wiggle gently if they’re stuck.

Step 6: Install the new capacitor and reconnect terminals

Mount the new capacitor in the same orientation and position as the old one. Slide the wire terminals onto the corresponding posts—match your photograph exactly. Push firmly until each terminal seats fully. Double-check that no wires are pinched or touching the compressor housing or fan blades.

Step 7: Restore power and test operation

Close the AC access panel and return to your interior control. Switch the breaker back on. Set the thermostat to cool and listen for the compressor to engage with a distinct click within 10–15 seconds. Feel the air coming from the vents; it should turn cold within 2–3 minutes. If the compressor hums but doesn’t click, or if there’s no cooling, turn off immediately and recheck your terminal connections.

What works

• After installing a fresh capacitor, the compressor engages with an audible click, and you’ll feel the pressure differential in your cabin within moments.
• This capacitor design fits across Dometic and Coleman-Mach rooftop units across many RV makes and model years, so you won’t be locked into hunting down a Riverstone-exclusive part.
• Replacement is a 15-minute job with just a socket set and a multimeter to verify the old component has genuinely failed.

What doesn’t

• Availability through online retailers can fluctuate; I’ve had to wait a week or longer for stock, which is tough when the thermometer reads 105.
• A capacitor replacement won’t fix a seized compressor or a failed circuit board; you need to confirm the capacitor is truly the problem with a multimeter or thermal imaging before you order anything.

There was a time when I swapped a capacitor, only to find the compressor still refused to turn over. For a moment, I panicked, thinking I had misdiagnosed the issue and the entire compressor was toast. As it turned out, the contactor on the control board had corroded, and I had to replace that too. So, order the RV AC dual run capacitor (Dometic/Coleman-Mach) as your first move, but don’t skip testing the contactor before assuming you need a new compressor.

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