Rotom HVAC Dual Run Capacitor 36-353R3744, 35/3MFD 370/440V Round

The Rotom 36-353R3744 is a round dual-run HVAC capacitor rated at 35/3MFD and 370/440 VAC. It supports two motor circuits from one body — the compressor through the HERM terminal and the condenser-fan motor through the FAN terminal, with C as the shared common connection. When the original capacitor fails, one or both motors may hum, struggle to start, operate intermittently, or overheat and trip on thermal overload.

Compatibility is determined by electrical specification and physical fit — not by equipment model number. Confirm both capacitance values, voltage rating, terminal arrangement, shape, and dimensions match the original before ordering.

Is This the Right Part?

Both capacitance values must match exactly. A 440V replacement may replace a 370V original when capacitance matches — the reverse is not permitted. Confirm the round body fits the existing mounting bracket before ordering.

Common Symptoms

• Compressor hums but fails to start or trips on thermal overload
• Condenser fan motor struggles to start or runs at reduced speed
• HVAC system short-cycles or shuts off shortly after starting
• Capacitor body visibly bulged, leaking, or reads out-of-tolerance on a capacitance meter

Check Before Replacing

• Test both capacitance values (35MFD and 3MFD) separately with a dedicated capacitor tester — both must be within ±5% tolerance
• Inspect the contactor for pitting or burning — a worn contactor is a common co-failure with a capacitor
• Verify the compressor and fan motor windings are not open or shorted before condemning the capacitor
• Confirm the electrical supply voltage and wiring connections are correct before replacing any component

Part Details

Specification-Equivalent Cross-References

Direct round replacements (35/3MFD, 370/440V, round):
TRCFD353 (Titan Pro), PRCFD353 (Packard), PRCFD353A (Titan HD), PPHD335440RD (ProParts HD), TP353440U (TradePro HD), 4JR0335 (DiversiTech), CD35+3X440R (Supco), 12077 (MARS Blue Box), 12977 (JARD / MARS), 14077 (MARS USA) — electrical ratings and round shape match; case dimensions vary among manufacturers. Confirm mounting strap diameter, capacitor height and terminal clearance before ordering.

Electrical equivalents — oval shape (confirm mounting fit before ordering):
TOCFD353 (Titan Pro, oval), POCFD353A (Titan HD, oval), 12085 (MARS Blue Box, oval), 12985 (JARD / MARS, oval), C4353L (Genteq / CAPCOM, oval) — electrically equivalent; oval case is not a mechanical drop-in for a round bracket. A different mounting strap or bracket may be required.

370V-only references — do not use in 440V applications:
12082 (MARS Blue Box, round), 12848 (JARD / MARS, oval), TOCD353 (Titan Pro, oval), 43-25135-17 (Rheem / Protech, oval) — use only when the equipment originally specifies a 370V capacitor. A 370V capacitor must not replace a capacitor required to operate at 440V.

Installation Notes

1. Disconnect and lock out all power to the condensing unit before opening the electrical compartment.
2. Photograph the original wiring and terminal labelling (C, FAN, HERM) before disconnecting.
3. Discharge the original capacitor safely before handling — capacitors can retain a dangerous charge after power is removed.
4. Compare the new capacitor with the original — verify capacitance, voltage, terminal arrangement, and physical dimensions.
5. Connect the replacement to the same terminals, confirm all connections are secure, restore power, and test compressor and fan operation.

HVAC capacitor diagnosis and replacement must be completed by a qualified HVAC technician. Capacitors can retain a lethal charge after power is disconnected. Do not attempt this repair without proper training and equipment.

Verified Compatible Models

Compatibility is specification-based — not model-specific. This capacitor fits any HVAC condensing unit requiring a round dual-run capacitor rated at exactly 35/3MFD, 370V or 440V, with C / FAN / HERM terminals, where the round body (1.97" dia × 4.33" H) fits the existing mounting bracket.

Fitment reminder: Match both capacitance values, voltage rating, terminal arrangement, shape, and physical dimensions to the original capacitor label before ordering.