The Brand Story
ProParts: The Small Can That Starts the Whole System
It is late afternoon in July, the house is warm, and the outdoor unit is humming but not running. A technician pulls the service panel, and there it is: a round metal can with its top swollen into a dome. A failed run capacitor is one of the most common service calls in air conditioning, and one of the cheapest to fix. ProParts capacitors are made for exactly that moment, a replacement part sized to match the one that came out of the unit.
Chapter 1 · What a capacitor does
A small push for a big motor
Single-phase motors need help to start turning and to run efficiently. A run capacitor stores and releases electrical energy to create the phase shift that keeps a compressor or fan motor turning smoothly. A dual run capacitor combines two capacitors in one round can: a larger section for the compressor and a smaller one for the condenser fan motor. Its rating is written as two numbers, such as 35/5, meaning 35 microfarads for the compressor (marked HERM) and 5 microfarads for the fan (marked FAN), with a shared common terminal (marked C).
When a capacitor weakens, the motor it serves runs hot, draws more current and may fail to start, which is why a capacitor check is part of nearly every no-cool diagnosis.
The Lineup
What ProParts offers at HVAC365
HVAC365 lists ProParts capacitors in common replacement ratings:
- Dual run capacitors: round 440-volt cans in ratings such as 35/5 microfarads, for condensing units that run the compressor and fan from one capacitor.
- Single run capacitors: for blower motors, fan motors and compressors wired with separate capacitors.
The replacement should match the original's microfarad rating, within its stated tolerance, and carry an equal or higher voltage rating. A 440-volt capacitor can replace a 370-volt one, but not the other way around. Always discharge a capacitor before handling it, and leave electrical work on condensing units to a qualified technician.
More HVAC parts and supplies and electrical components and controls sit alongside them.
At a Glance
ProParts capacitors at a glance
- Product type
- HVAC run capacitors
- Styles
- Dual run and single run
- Case
- Round metal can
- Voltage rating
- 440V
- Example rating
- 35/5 microfarads
Questions
Frequently asked questions about ProParts
What does 35/5 mean on a ProParts capacitor?
It is a dual run capacitor rating: 35 microfarads for the compressor (HERM terminal) and 5 microfarads for the condenser fan motor (FAN terminal), sharing a common terminal.
Can I use a 440V capacitor in place of a 370V capacitor?
Yes. A 440-volt capacitor can replace a 370-volt capacitor with the same microfarad rating, but a 370-volt capacitor should not replace a 440-volt one.
How do I know if a run capacitor has failed?
Common signs are a bulging or leaking top, a compressor or fan that hums but will not start, and a microfarad reading on a meter that falls outside the tolerance printed on the label.
Is a dual run capacitor the same as a start capacitor?
No. A run capacitor stays in the circuit while the motor runs. A start capacitor gives a short, strong boost only at startup and is usually part of a hard start kit.
