Compressor Won T Start On Air Conditioner

Introduction

An air conditioner that won’t cool your home can be incredibly frustrating, especially during sweltering weather. A primary suspect is often the compressor the heart of your AC unit. When the compressor won’t start, your AC can’t circulate refrigerant, and thus, it can’t cool. This situation is common during peak summer months when AC units are working overtime, and addressing it quickly is crucial to prevent further damage and restore comfortable living conditions. Explore more in our Air Conditioner Troubleshooting 4 collection.

Common Causes of compressor won t start on air conditioner

Several factors can prevent your AC compressor from starting. Here are some common causes:

• Power Issues: A tripped circuit breaker or blown fuse can cut power to the unit.
• Faulty Capacitor: Capacitors provide the initial jolt of energy needed to start the compressor. If it’s weak or failed, the compressor won’t start.
• Dirty Condenser Coils: Dirty coils prevent proper heat exchange, causing the compressor to overheat and shut down.
• Refrigerant Leaks: Low refrigerant levels can trigger safety mechanisms that prevent the compressor from running to avoid damage.
• Overheating: The compressor may overheat due to poor ventilation or excessive use.
• Hard Start Kit Failure: If your unit has a hard start kit, this component may be malfunctioning.
• Contactor Problems: The contactor is an electrical relay that sends power to the compressor. If it’s damaged or worn, it may not engage properly.
• Locked Rotor: In rare cases, the compressor itself may be physically seized or “locked,” preventing it from starting.

Symptoms Checklist

Here are some indicators that your AC compressor might be the problem:

• The AC unit turns on, but the air is not cooling.
• You hear a humming sound from the outdoor unit, but the fan isn’t running, or the compressor doesn’t seem to kick in.
• The circuit breaker for the AC unit trips frequently.
• The outdoor unit is completely silent.
• You notice frost or ice buildup on the refrigerant lines.

How to Fix compressor won t start on air conditioner Step-by-Step Guide

Follow these steps to troubleshoot your AC compressor:

1. Check the Thermostat: Ensure the thermostat is set to “cool” and the temperature is set lower than the current room temperature.
2. Inspect the Breaker: Locate the circuit breaker for your AC unit in the electrical panel and ensure it hasn’t tripped. Reset it if necessary.
3. Check the Disconnect Switch: There is usually a disconnect switch near the outdoor unit. Make sure it’s in the “on” position.
4. Examine the Condenser Coils: Check the outdoor unit’s condenser coils for dirt, leaves, or debris. Clean them gently with a garden hose (power OFF).
5. Listen for Sounds: If you hear a humming sound but the compressor isn’t starting, it could be a capacitor issue.
6. Visually Inspect the Capacitor: (With the power OFF at the breaker!) Locate the capacitor inside the outdoor unit. Look for bulging, leaking, or any signs of damage. Do not touch the capacitor directly, as it can hold an electrical charge.
7. Check for Ice Buildup: If you see ice on the refrigerant lines, turn off the AC and let it thaw completely. This could indicate a refrigerant leak or airflow problem.
8. Inspect the Contactor: (With the power OFF at the breaker!) Look at the contactor. It’s a switch that sends power to the compressor. Look for signs of burning or corrosion.
9. Check the Fan Motor: Make sure the fan blades can spin freely. If they are stuck, try lubricating the motor bearings (with the power OFF at the breaker!).
10. Reset the Compressor (if applicable): Some compressors have an internal thermal overload protector that can be reset. Consult your AC unit’s manual for instructions.
11. Wait and Restart: If the compressor overheated, give it a few hours to cool down before trying to restart it.

Fix the Issue Without Buying Parts

Before considering replacements, try these free methods:

• Cleaning: Regularly clean the condenser coils to ensure proper airflow.
• Resetting: Resetting the circuit breaker or disconnect switch can sometimes resolve temporary issues.
• Inspection: Regularly inspect the unit for signs of damage or wear.
• Maintenance: Regular professional AC maintenance can prevent many compressor issues.

When Replacement Might Be Necessary

If you’ve tried all the troubleshooting steps and the compressor still won’t start, replacement may be necessary. Common failing parts include the capacitor, contactor, or even the entire compressor unit itself. Replacement costs can range from $150-$300 for a capacitor or contactor (including labor) to $800-$2500+ for a compressor, depending on the unit’s size and complexity. It’s wise to get quotes from multiple HVAC technicians before making a decision.

Safety Warning

Take these precautions when working with your AC unit:

• Always turn off the power to the AC unit at the circuit breaker and disconnect switch before performing any maintenance or repairs.
• Never touch electrical components, especially the capacitor, without properly discharging them first.
• Avoid working on the unit in wet conditions.
• If you’re uncomfortable with any of these steps, call a qualified HVAC technician.

Tools You May Need

Here’s a list of tools you might find useful:

• Screwdrivers (Phillips and flathead)
• Wrench set
• Garden hose
• Multimeter (for testing electrical components use with caution!)
• Work gloves
• Safety glasses

FAQ

Here are some common questions and answers:

• Q: Why is my AC compressor humming but not starting?
  A: This often indicates a faulty capacitor that’s not providing enough power to start the motor.
• Q: How do I know if my AC compressor is locked up?
  A: If the compressor is making a loud grinding noise and tripping the breaker immediately, it might be locked.
• Q: Can I replace the capacitor myself?
  A: Replacing a capacitor is possible for some homeowners with electrical experience, but it’s crucial to handle it with extreme caution and discharge it properly.
• Q: How often should I have my AC unit professionally serviced?
  A: It’s generally recommended to have your AC unit serviced at least once a year, preferably before the start of the cooling season.

Conclusion

Troubleshooting an AC compressor that won’t start can seem daunting, but by following these steps, you can often identify and resolve the issue yourself. Remember to prioritize safety and start with the simplest solutions. If you’ve exhausted these steps and are still experiencing problems, it’s best to call a qualified HVAC technician for professional assistance. Many AC problems are resolved with some simple steps, so get your hands dirty and hopefully save some money!. Discover more free resources across our collection library.

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