When choosing a replacement, you must match the microfarad rating exactly. You can use a higher voltage rating, but you must never use a lower one. Pick a round or oval case that fits inside your unit's mounting bracket.
Parts with these numbers
45+5 MFD 440/370V Round Dual Run Capacitor (Bluefin CPDRR1-455)
45+5 MFD 440/370V Round Dual Run Capacitor (Titan Pro TRCFD455)
45+5 MFD 440/370V Oval Dual Run Capacitor (Titan Pro TOCFD455)
- µF (MFD): must be the same, like 45/5
- Volts: same or higher (440 can replace 370)
- Shape: round or oval, to fit the bracket
What the Numbers Mean
The label on a dual run capacitor lists capacitance and voltage. Capacitance is measured in microfarads, which is written as MFD, uF, or µF. A 45/5 rating means the part has two separate sections inside. The larger 45 µF rating runs the compressor, while the smaller 5 µF rating runs the outdoor fan motor.
The voltage rating shows the maximum electrical pressure the part can handle. A 440/370V rating means the capacitor can safely operate in systems needing 370 volts or 440 volts. You can always use a 440V part to replace a 370V part, but you must never replace a 440V part with a 370V part.
- 45 µF: Capacitance needed for the compressor motor.
- 5 µF: Capacitance needed for the outdoor fan motor.
- 440/370V: Voltage rating that covers both 370V and 440V applications.
How to Read the Terminals on the Old Part
A dual run capacitor has three sets of terminal posts on top. Each post connects to a different motor circuit in your outdoor cooling unit.
Take a photo of every wire before removing the old part. Move the wires one at a time to the matching posts on the new capacitor to avoid wiring mistakes.
- C: Common terminal that connects to the incoming line voltage.
- HERM: Hermetic terminal that connects to the compressor.
- FAN: Fan terminal that connects to the outdoor condenser fan motor.
Comparing Shapes and Part Options
Capacitors with the same ratings do the same electrical job, but their physical shape can differ. Round and oval shapes are both available in the 45/5 MFD 440/370V rating. Check your outdoor unit to see which shape fits inside the metal mounting bracket and allows the wires to reach.
Bluefin makes a round model under part number CPDRR1-455. Titan Pro offers a round version under part number TRCFD455, which replaces CAP-45/5/440R, CD45-5X440R, TRCD455, and CPDRR1-455. Titan Pro also makes an oval model under part number TOCFD455, which replaces CAP-45/5/440, CD45-5X440, and POCFD455.
Common Signs of a Bad Capacitor
Capacitors wear out over time from heat and normal use. When this part fails, the outdoor fan motor or compressor will not receive the electrical boost needed to run.
A common sign of failure is an outdoor fan that hums loudly but will not spin. Homeowners sometimes mistake this for a broken fan motor when the motor itself is still fine. The top of the metal can may also swell or bulge outward when the capacitor goes bad.
How to confirm it fits
- Turn off electrical power at the breaker and pull the outdoor disconnect, then test for power.
- Discharge the old capacitor terminals using an insulated tool.
- Check the microfarad rating on the old label to make sure it reads 45/5, 45+5, or 45/5 MFD.
- Check the voltage rating on the old part to confirm it is 370V or 440V.
- Look at the shape of the existing metal can and bracket to choose between a round or oval replacement.
Questions
Can I replace a 370V capacitor with a 440V capacitor?
Yes. A 440V capacitor can safely replace a 370V capacitor. You must never go lower than the voltage rating on your original part.
Can I use an oval capacitor instead of a round capacitor?
Yes, as long as the ratings match and the oval can fits securely into the mounting bracket inside your unit.
What is the difference between a dual run capacitor and a start capacitor?
A dual run capacitor stays in the circuit to run two motors and has three terminals. A start capacitor is used in hard start kits and lists a microfarad range, such as 88 to 108 µF.
What should I do if my fan hums but does not spin?
A fan that hums without spinning often points to a bad capacitor rather than a broken motor. Turn off power at the breaker and outdoor disconnect before inspecting the part.
Related guides
Brand names and part numbers are used only to show fit. HVAC Fitter is not affiliated with, authorized by, or endorsed by any equipment maker. If you are not sure a repair is safe for you, call a licensed HVAC technician.