Forest River Berkshire – AC Capacitor & Fan Motor Service

I’m standing on the ladder with my head tilted up into the rooftop AC shroud, one hand on the blower housing and the other holding a multimeter. The hum is there — the compressor is spinning fine — but the fan blade barely moves. It’s 98 degrees outside, and inside the Berkshire it’s climbing toward 82. I’ve seen this pattern a dozen times: the motor gets voltage, tries to turn, then gives up. Either the capacitor is shot or the fan motor itself is on the way out. On a Forest River Berkshire, when your cooling system starts acting like this during summer heat, you’re almost always looking at a failed run capacitor or a weakening fan motor — and the good news is both are parts-and-labor jobs that cost anywhere from $15 to $80 in components if you’re willing to do the work yourself, versus the $300-plus mobile tech bill you’ll get if you call someone out to the campground. This is the repair I talk you through the way I’d explain it to a friend at the picnic table: step by step, no fluff, assuming you’ve got a wrench and a willingness to learn.

The Run Capacitor That Restarts Your Dometic AC When the Fan Quits

When your rooftop Dometic unit hums steadily but the fan refuses to spin, or it cycles off after a few minutes of weak operation, the culprit is almost always a capacitor that’s lost its charge — and swapping it out is the fix that gets cool air moving again without replacing the whole motor.

Parts and Tools

• Replacement run capacitor matched to the microfarad and voltage rating stamped on the old capacitor (typically 60/5 MFD for Dometic rooftop units) — check current price
• Replacement fan motor assembly if the capacitor tests good but the motor still won’t spin — check current price
• Digital multimeter capable of reading AC voltage and resistance
• Socket set and wrench to fit the bolts securing the capacitor bracket and motor housing
• Needle-nose pliers for disconnecting spade terminals from the capacitor leads
• Insulated screwdriver for any terminal adjustments

Step-by-Step Instructions

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

Locate your main 120V breaker panel inside the Berkshire and flip the breaker labeled for the rooftop AC to the OFF position. Wait 30 seconds, then go back outside and try the AC wall switch to confirm no power is reaching the unit. This prevents shock when you touch the capacitor terminals. Even with the breaker off, capacitors can hold a charge, so treat every connection as live until you’ve verified it with your multimeter.

Step 2: Access the rooftop AC shroud and photograph the wiring

Climb onto the roof using a stable ladder and locate the Dometic unit. Remove the shroud bolts (usually four corners) and lift the cover away. Before touching anything, take a clear photo of how the capacitor terminals connect to the motor leads — spade connectors on top, typically two wires. This photo is your reassembly map. Note the position of the capacitor bracket so you can reinstall the new one identically.

Step 3: Test the capacitor with your multimeter

Set your multimeter to the resistance (ohms) setting. Touch one probe to each capacitor terminal. A good capacitor shows a brief needle deflection then returns to infinity. A dead capacitor reads zero or stays at a fixed low number. If the reading is normal, the motor itself is likely failing. If the capacitor is bad, proceed to removal. If the motor is the problem, you’ll need to replace the motor assembly instead.

Step 4: Disconnect the capacitor terminals safely

Using needle-nose pliers, gently pull each spade connector off the capacitor terminals. Do not yank the wires themselves — grip the connector only. Set the wires aside where they won’t touch metal. Unscrew or unbolt the capacitor bracket from its mounting point (usually two bolts through the bracket ears into the shroud frame). Lift the old capacitor out and set it aside. Do not discard it yet — you need to read the microfarad and voltage rating from its label.

Step 5: Install the new capacitor and reconnect terminals

Position the new capacitor into the bracket so it sits exactly as the old one did. Bolt it down firmly but do not overtighten — snug is enough. Slide the two spade connectors back onto the capacitor terminals, pressing until they click or seat fully. Double-check that both connectors are seated and not loose. Verify your photo matches the new setup before moving on.

Step 6: Reinstall the shroud and restore power

Lower the AC shroud back into place and reinstall all four corner bolts, tightening evenly so the shroud sits flat. Climb down from the roof. Go inside and flip the AC breaker back to ON. Set the thermostat to cool and listen for the compressor to start. The fan should now spin smoothly and pull air through the return vents.

Step 7: Test cooling performance and monitor for 15 minutes

Let the AC run for at least 15 minutes while you monitor the interior temperature and listen for any unusual sounds. The fan should run continuously without stuttering or cycling off. Feel the air coming from the vents — it should be noticeably cool within 5 minutes. If the fan still won’t spin or the compressor hums without the fan turning, the motor is bad and needs replacement. If cooling is restored, the job is complete.

What works

• Fits Dometic 3312195.000 units as a direct bolt-in — bracket stays put, wiring harness doesn’t need rewiring, you just unbolt the old one and bolt the new one down.
• The 60/5 MFD specification matches factory OEM exactly, so your motor gets the full electrical kick it needs to turn over under load instead of that sad, half-speed spin you get from a mismatched aftermarket part.
• Built to handle the punishment of full-time operation — this isn’t the bargain-basement capacitor that starts bulging after a couple of summers and fails again when you need it most; it’s engineered for the thermal stress of running 12+ hours daily in a rig that lives outside year-round.

What doesn’t

• You have to cut power at the breaker before you touch it — a charged capacitor stores enough voltage to deliver a serious shock, and skipping that step is not worth the risk.
• If you order through Amazon, plan on 5–7 days for delivery; if you’re already in a heat wave, you’re going to suffer through it with a portable AC unit or just riding out the temperature indoors until the part shows up.

I second-guessed myself the first time I pulled a capacitor and the multimeter reading looked borderline — not completely dead, just weak — so I almost ordered a whole motor instead of trusting the failure mode. Order the 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 and have it on hand before summer hits.

This post contains affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you.