Run Capacitor check and change out checklist.
1. Determine this component is your problem.
There are at least two if not three run capacitors (one for each motor) on your A/C unit.
Your blower motor (indoor fan) will not be coming on. You can check this by turning, at your thermostat, the fan switch from auto to on and note there is no airflow at the registers in the home. Often, in this case you will see a coat of ice on the suction line of the copper pipes. This is because the compressor is still trying to move refrigerant but with no warm air blowing across it the coil, the pipe and coil ice up.
TURN YOUR UNIT TO 'OFF' AT THE THERMOSTAT. THIS CONDITION CAN TURN UGLY FAST FOR YOUR COMPRESSOR IF LIQUID REFRIGERANT GETS BACK TO IT. This will also help your overheated compressor to cool down and work again. *Caution this can be misdiagnosed as a very dirty evaporator coil* call me if you need help ruling this out.
If the outdoor fan motor and/or compressor do not come on there is a run capacitor that powers these two motors as well This is where you see the dual run capacitor, you may see two separate caps as well, but less common. The fan blades on the condenser fan motor should still move freely (not seized up) and you can check this by turning the blades with a stick or screwdriver through the top of the unit. The dual run capacitor has three terminals C - common, Fan - for fan motor leads, and 'Herm' referring to the compressor leads. All that really matters is you hook the leads back up to the same terminals. On the single run capacitor (with two terminals on to) it does not matter (common can be on either side and the motor leads on the other).
2. Before opening unit PULL THE DISCONNECT SWITCH OR UNPLUG THE BLOWER MOTOR. IF NEITHER IS AVAILABLE TURN OFF THE UNIT AT THE CIRCUIT BREAKER PANEL.
3. The run capacitors should be easy to find and readily accessible.
4. Discharge the run capacitor using an insulated screwdriver. Holding the insulated handle, touch each terminal across to the other terminals, basically shorting them together.
5. If the run capacitor is visibly bulged or has leaked out, it will be obvious. Often times the run cap looks good and can then be tested with a multimeter with a MFD (microfarad) mode. The measured MFD should be within 5% of the stated rating on the side of the cap.
6. Take a photo and/or mark the wires that come off the run capacitor.
7.. If the cap is bad simply replace with exact MFD rating and voltage can be the same or higher on the new cap (voltage is either 370 volts or 440, I just put 440v on all my new ones).
8. Re-attach the wires exactly.
9. Power up the unit at the disconnect or breaker panel.
10. You can test your work by turning (at the thermostat) the fan switch from auto to on. The blower should come on now. If the run cap in the outdoor unit was bad you can use the same insulated screwdriver (holding the insulated screwdriver) and push the plunger on the contactor in. The condenser fan motor and compressor should come on. Release this after a couple of seconds - it is just a test.
11. Button the unit up and you should be back in business. If the compressor does not come on at first, wait. It has an internal protection that turns itself off when it overheats. It needs to cool to appx 115 degrees for the motor to operate again. That can take awhile in Phoenix (we use ice bags in a pinch) but time will do it as well.
8. Congratulations you just saved yourself at least 100$ and feel great!!!!