What are Capacitors in an AC?
In an air conditioner, a capacitor is an electrical component that helps the motors start and run smoothly.
AC capacitors store electrical energy and release it at the right moment to:
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Start the compressor
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Start and run the fan motor
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Improve efficiency and reduce power loss
⚙️ Why Capacitors Are Needed in AC
AC motors are single-phase motors, and they cannot start by themselves.
The capacitor:
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Creates a phase shift
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Provides extra starting torque
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Keeps the motor running at proper speed
Without a capacitor → the motor will hum but not start.
🧰 Types of Capacitors Used in AC
1️⃣ Start Capacitor
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Used only during startup
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High capacitance
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Works for a few seconds
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Connected through a relay
📌 Example: 88–108 µF
2️⃣ Run Capacitor
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Works continuously
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Lower capacitance
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Improves efficiency & performance
📌 Example: 25 µF, 35 µF, 45 µF
3️⃣ Dual Run Capacitor (Most Common)
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One capacitor for two motors
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Used for compressor + fan motor
📌 Example: 35/5 µF
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35 µF → Compressor
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5 µF → Fan motor
⚡ Voltage Ratings (Very Important)
Common AC capacitor voltages:
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370V
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440V
✔ Always use same µF
✔ Voltage can be same or higher, never lower
🚨 Signs of a Bad AC Capacitor
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AC not starting
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Outdoor fan not spinning
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Humming sound
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Compressor overheating
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AC trips breaker
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Weak or no cooling
🛠️ Where Capacitors Are Located
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Mostly in the outdoor unit
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Inside the electrical control box
🔍 Safety Note
⚠️ Capacitors can hold charge even after power is OFF.
Always discharge before handling.
🧠 Quick Summary
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Capacitor = starter + helper for AC motors
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Essential for compressor and fan
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Wrong value can damage AC
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One of the most common AC failures
If you want, I can also explain:
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How to check an AC capacitor
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Wiring terminals (C, FAN, HERM)
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Difference between 370V vs 440V
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How to select the correct capacitor
Arise Aircon – Business Details
Business Name: Arise Aircon
Address: 17, Dhuleshwar Garden, C-Scheme, Jaipur, Rajasthan, India
Mobile Number: +91 88909 36664
Email ID: ariseaircon77@gmail.com