Dual run capacitors are commonly used in HVAC (heating, ventilation, and air conditioning) units. Dual capacitors have three terminals, unlike regular run capacitors, which have only two. Electrically, they are the same as run capacitors that have two terminals. Using a dual run capacitor allows you to save space if you have a small mounting area. The terminals are also clearly marked, making it easy to hook it up to the different components of your air conditioner.
Dual capacitors usually have connections marked "C" for "common," "H" or "HERM" for the hermetic compressor, and "F" or "FAN" for the fan in an HVAC unit. They also have two different capacitance ratings (for example, 40/5 uf). The larger value is always connected to the compressor (40 uf in the example), while the smaller value will always be connected to the fan (in this case, 5 uf).

SPECIFICATIONS:
Model: CBB65 （Universal model）
Case Material: unpainted aluminum case.
Dielectric Material: metallized polypropylene film.(NON-PCB)
Available Capacitance: 40+5 uF
Capacitance Tolerance: ±5%.
Operating temperature: -40℃ to +70℃/-104℉ to +158℉.
Frequency: 50/60 Hz.
Safety rated: 10,000 AFC - Available Fault Current.
Operating Life: 60,000 hours with 94% survival (In accordance with the EIA­456 Industry Standard).
Dissipation Factor: 0.1% maximum.

When an AC capacitor replacement is necessary, you'll experience any number of common symptoms, including:
1)The voltmeter says there are too few microfarads.
2)It's swollen like a balloon. .
3)The capacitor leaks oil.
4)Your air conditioner doesn't turn on at all, Or it's running but doesn't dispense cool air and so on.
Sometimes, an old, rusty-looking capacitor will still read at the appropriate level of microfarads. It really comes down to the voltmeter reading, physical swelling, and/or the presence of oil.