An air conditioner capacitor plays a crucial role in starting the compressor and fan motors in the air conditioning system. It works to improve efficiency by correcting the power factor coming into the unit. Over time, the capacitor can become faulty due to wear and tear or power surges. A failed capacitor will cause the air conditioner to stop cooling properly or not turn on at all.
Replacing a bad capacitor is an easy, cost-effective DIY repair that can get your air conditioner running again and save you money on service calls. This guide will walk you step-by-step through the process to help you safely replace the capacitor yourself.
Here’s what we’ll cover:
- Understanding capacitors and how to identify failures
- Safety precautions when working with electrical components
- Detailed, step-by-step instructions for replacing the capacitor
- Tips for maintaining your air conditioner and new capacitor
Equipped with this guide, you’ll have the knowledge to efficiently replace a faulty air conditioner capacitor and keep your home cool all summer long.
Understanding the Capacitor
Before replacing your air conditioner capacitor, it helps to understand what a capacitor does and why it can fail.
What is an Air Conditioner Capacitor?
An air conditioner capacitor is an electrical component that stores energy. It works alongside the compressor and fan motors to smooth out voltage peaks and improve efficiency.
There are two common types of capacitors found in air conditioning units:
- Start capacitor – Provides the jolt of energy needed to start the compressor and fan motors. Once running, start capacitors disengage from the circuit.
- Run capacitor – Stays connected to run the motors after start-up. Helps motors run smoothly.
Capacitors contain conductors separated by a dielectric material to store the electric charge. They either come as separate start-and-run capacitors or a dual capacitor that performs both functions.
Signs of a Faulty Capacitor
A faulty capacitor exhibits certain signs and symptoms, indicating it needs replacement. Some signs your air conditioner capacitor has failed or is going bad include:
- Air conditioner not starting or fan not spinning
- Unit starts but immediately trips the breaker or blows fuses
- Fan motors run hot and overheat
- Compressor makes humming noise but won’t start
- High-pitched squealing or screeching noises
- Unit runs erratically or inefficiently
- Capacitor leaks oil bulges at top, or shows physical damage
Replacing bad capacitors early on can prevent further damage and restore cooling efficiency.
Safety Precautions
Working with electrical components can be extremely dangerous if proper safety precautions are not taken. Make safety your top priority when replacing an air conditioner capacitor.
Safety Gear Needed
- Electrical gloves to prevent shock
- Safety goggles for eye protection
- Long sleeves and pants without holes or tears
- Work boots with rubber soles for insulation
Tools Needed
- Multi-meter to safely discharge capacitor
- Voltage Sniffer to confirm power is off
- De-energized Outlet Tester
- Phillips and standard screwdrivers
- Needle nose pliers
- 25-75 MFD Dual Capacitor replacement part
Discharging the Capacitor
It’s crucial to properly discharge the old capacitor to prevent serious shock injury or death. Here is a safe discharge method:
- Turn OFF power to air conditioner at the breaker
- Twist together the old capacitor’s wires to short the terminals
- Carefully touch a screwdriver across capacitor terminals to discharge remaining energy
- Use a voltmeter to confirm zero voltage before handling capacitor
With safety first, you’re ready to confidently replace the capacitor.
Step-by-Step Replacement Guide
Follow these step-by-step instructions to safely install a new dual-run capacitor in your air conditioning unit:
Step 1: Safety First
Before touching any wires or components, double-check the power is switched OFF at the breaker. The voltage sniffer will light up if power is still flowing. Only proceed when you have confirmed the circuit is de-energized.
Locate the Capacitor
- The capacitor is usually mounted in a metal box attached to the body of the air handler unit or compressor.
- Most capacitors have their microfarad (MFD) rating printed on top with the negative and positive terminals marked.
Remove the Old Capacitor
- Disconnect and straighten any bent wire connections on the faulty capacitor.
- Take photos of the wires and terminals to help with proper re-wiring later.
- Remove any screws holding the capacitor in place, then gently detach it from its bracket.
Install New Dual Run Capacitor
- Ensure your replacement capacitor matches the old one’s voltage and MFD rating. Using undersized or oversized capacitors can damage the system.
- A dual-run capacitor with 45+5 MFD is usually ideal for most air conditioner units.
- Slide in the new capacitor and securely screw it to the metal bracket.
Wiring Connections
| Terminal | Wire Color | Connect to |
| C | Yellow | Compressor motor wires |
| FAN | Blue | Fan motor wires |
| HERM | Red | Mounting bracket |
- Re-connect each labeled wire to the matching capacitor terminal.
Reconnect Power and Test
- Carefully turn power back ON at the breaker.
- Set the thermostat below room temperature to activate cooling mode.
- Listen and confirm the compressor and fans turn on shortly after calling for cool air.
- Check that air blows from the vents within a few minutes to indicate proper operation.
You’ve successfully installed the new capacitor if all systems activate on demand! Notify an HVAC technician immediately if the air conditioner still doesn’t start or trips the breaker.
Additional Tips
Replacing old capacitors annually before the cooling season starts is best practice to keep your A/C running efficiently all summer long.
Here are some additional maintenance tips to preserve system performance and your new capacitor:
Handy Table for Remembering Recommended Checks
| Maintenance Check | Frequency | Why It’s Important |
| Check capacitor terminals and connections | Seasonally | Ensures secure wire connections to prevent short circuits |
| Test capacitor microfarad values | Annually | Indicates capacitance wears over time, requiring replacement |
| Clean air conditioner coils and fins | Seasonally | Prevents blockages lowering operating efficiency |
| Replace air filters monthly | Monthly | Keeps airflow unrestricted for heat transfer |
| Clear debris around outdoor compressor | Seasonally | Allows proper ventilation to prevent overheating |
| Check refrigerant charge levels | Annually | Prevents operation with low refrigerant reducing cooling capacity |
Following these best practices for system maintenance keeps an A/C running at peak efficiency – maximizing the lifespan of the new capacitor and beyond.
Also Read: How to Clean Your Air Conditioner the Easy Way
Conclusion
Replacing a bad air conditioner capacitor is an economical DIY repair you can totally tackle yourself after reading this guide. Now you know how to:
- Identify signs of a faulty capacitor at fault for cooling issues
- Take proper safety precautions when servicing electrical equipment
- Discharge old capacitors safely before removal
- Install replacement capacitors following wiring diagrams
- Carry out seasonal maintenance for optimal performance
With this DIY knowledge under your belt, you can restore cooling quickly when capacitor failure strikes and keep spare parts on hand for future issues. Stay cool and save money this summer by leveraging these air conditioner capacitor replacement tips.