Answer
Jul 28, 2025 - 04:29 AM
Unlike car AC systems, there is no way to recharge the AC if there is a freon leak, the AC would need to be replaced.
⚡ Step-by-Step: How to Test the Capacitor in your RV AC
1. Kill All Power
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Disconnect from shore power, turn off inverter, & flip off breaker feeding the AC unit.
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Do not test with power connected.
2. Remove AC Shroud
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Go on the roof.
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Unscrew the outer plastic shroud and locate the capacitor box (usually a metal or plastic cover near the compressor/fan).
3. Discharge the Capacitor
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Capacitors can hold a charge long after power is cut. You must discharge it. DO NOT TOUCH PINS without doing this first.
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Short the terminals using an insulated screwdriver across each pair:
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Start to Common
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Run to Common
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⚠️ You may hear a snap. That’s normal. It means the charge is gone.
4. Remove the Wires
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Take a photo first so you know which wires go where.
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Disconnect the terminals
5. Test with the Multimeter
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Set the multimeter to capacitance mode (μF).
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Touch the probes to:
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C and FAN to test fan side
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C and HERM to test compressor side
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6. Compare to Rating
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Capacitor will say something like:
45 + 5 μF ±6% 370/440V-
That means 45μF for the compressor, 5μF for the fan.
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Your reading should be within ±6% of each value:
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45μF: Acceptable = 42.3 to 47.7μF
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5μF: Acceptable = 4.7 to 5.3μF
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If you're outside that range or it reads “OL” (overload/open), the capacitor is bad. Replace it.
🚫 Don’t Have Capacitance Mode?
If your meter doesn't have μF, you can still check basic health with resistance:
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Set to ohms (Ω).
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Touch probes to
CandHERMorFAN. -
You should see the resistance climb, then reset (charging the meter). No change = bad capacitor.
Replace with the same specs:
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μF or MFD (microfarad) rating must match
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Voltage rating can be equal or higher (never lower)
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