How to Tell if a Capacitor is Bad in a Commercial HVAC System

A faulty capacitor is one of the most common causes of HVAC motor and compressor failure.

Common symptoms include:

• Motor humming but not starting  
• Unit randomly shutting off  
• Weak airflow  
• Tripped breaker  

To test a capacitor:

1. Turn off power completely.
2. Discharge the capacitor safely.
3. Use a multimeter with capacitance mode.
4. Compare the reading to the rated value printed on the label.

If the reading is outside ±6%, the capacitor should be replaced.

Always use a properly rated replacement capacitor.