Capacitance Testing

• 1). Turn off the main AC circuit breaker to the RV. The circuit breaker is located in the RV's electrical load center. Remove the shore power AC connection to the RV if it is connected.
  
  
• 2). Climb on to the RV roof and remove the air conditioner protective housing by unscrewing all Phillips head screws located around the base of the housing.
  
  
• 3). Locate the motor run and start capacitor enclosure. The enclosure is typically located near the top right corner of the air conditioner assembly when facing towards the front of the RV. It may also have a wiring diagram sticker on it. Remove the enclosure cover screws and cover.
  
  
• 4). Inspect the enclosure for two capacitors. The motor run capacitor is typically a silver oval-shaped canister two to three inches in length. The motor run capacitor is either black or silver, cylindrical in shape and is three to four inches in length.
  
  
• 5). Discharge each capacitor by shorting the electrical terminals located on the top of the capacitor using the flat blade screwdriver.
  
  
• 6). Remove the electrical leads from the motor run capacitor, taking note of what terminal each wire is connected to.
  
  
• 7). Measure the capacitance of the motor run capacitor by switching the multimeter to capacitance mode and place the positive lead (red) on positive or "+" terminal of the capacitor and the negative (black) lead on the negative or "-" terminal.
  
  
• 8). Compare the reading to the value printed on the side of the capacitor. If it is out of range, replace the capacitor. Repeat Steps 6 and 7 to test the motor start capacitor.
  
  

Resistance Testing

• 1). Switch the multimeter to Ohms mode. Place the positive lead (red) on the positive or "+" terminal of the capacitor and the negative (black) lead on the negative or "-" terminal.
  
  
• 2). Check to see if the resistance measurement gradually increases to near infinity. If it does not, the capacitor is leaky and requires replacement. If there is no resistance --- a zero reading --- the capacitor is shorted and requires replacement. If there is no resistance reading, the capacitor has an open circuit and requires replacement.
  
  
• 3). Repeat Steps 1 and 2 for the motor start capacitor.