If your air compressor won’t start, hums without turning on, or keeps tripping breakers, there’s a good chance the capacitor has failed. The capacitor is a small but critical component that stores electrical energy and delivers the jolt needed to start and run the motor. Choosing the wrong one can damage your compressor or keep it from working at all. The big question many owners ask is: what capacitor does my compressor need?
In this guide, we’ll explain the different types of compressor capacitors, how to choose the right one, and which high-quality replacements are worth buying today. Whether you own a portable 120V unit or a large two-stage shop compressor, the right capacitor ensures smooth, reliable operation.
Quick Picks: Best Replacement Capacitors
- Best Overall: TEMCo Industrial AC Motor Start Capacitor (440–480V) – Rugged, reliable, and covers a wide range of compressors.
- Best Budget: Supco SPP6 Hard Start Capacitor – Affordable and effective for smaller shop compressors.
- Best Premium: Packard Start & Run Dual Capacitor Combo – Perfect for heavy-duty and two-stage compressors needing both types replaced together.
Buyer’s Guide: Choosing the Right Compressor Capacitor
Picking a capacitor isn’t just about price—it’s about making sure it matches your motor’s requirements. Here are the key things to look at:
- Type of Capacitor: Most compressors use a start capacitor (gives the initial boost) and a run capacitor (keeps the motor running smoothly). Some units need both.
- Voltage Rating: Match the voltage (usually 250V, 370V, or 440V). A higher rating is okay, but never lower.
- Microfarads (µF): The most important number. Must match within ±10% of your original capacitor’s rating.
- Size & Shape: Ensure the replacement physically fits in your compressor’s capacitor housing.
- Quality & Brand: Cheap capacitors often fail early. Stick with trusted industrial brands like TEMCo, Packard, or Supco.
Detailed Product Reviews
1. TEMCo Industrial Motor Start Capacitor 440–480V
Who it’s for: Owners of larger shop compressors needing a reliable replacement.
- Key Benefits: Wide voltage range, durable design, 1-year warranty.
- Pros: Built tough, trusted industrial supplier, precise µF rating.
- Cons: Slightly higher cost than generic models.
Final Verdict: The safest choice for professional-grade compressors. Check Price
2. Supco SPP6 Hard Start Capacitor
Who it’s for: DIYers or small shop owners with struggling compressors.
- Key Benefits: Boosts starting torque, compact design, inexpensive.
- Pros: Affordable, easy installation, works with many brands.
- Cons: Not suitable for very large motors.
Final Verdict: A great budget-friendly fix. See Today’s Price
3. Packard Dual Run Capacitor Combo
Who it’s for: Compressors needing both start and run capacitors replaced.
- Key Benefits: Combines start and run capacitors, compact form factor.
- Pros: Saves space, simplifies wiring, long-lasting.
- Cons: Must match exact specifications to your motor.
Final Verdict: Best for replacing both capacitors at once. Check Price
4. Genteq 370V Run Capacitor
Who it’s for: Shop compressors that require continuous running stability.
- Key Benefits: Trusted HVAC brand, accurate microfarad rating, reliable operation.
- Pros: Widely available, proven quality, excellent for continuous-duty units.
- Cons: Slightly bulky compared to newer compact capacitors.
Final Verdict: A time-tested choice for steady performance. View Price
5. Mars 1220 Start Capacitor
Who it’s for: Compressors needing a high-strength start boost.
- Key Benefits: High torque output, compact, affordable.
- Pros: Strong starting power, easy replacement, solid reputation.
- Cons: Limited to smaller motors under 5 HP.
Final Verdict: Reliable option for small shop units. See Price
6. PowerWell PW-70/5 Dual Capacitor
Who it’s for: Compressors needing a dual start/run replacement with budget value.
- Key Benefits: Combines both functions, 70/5 µF rating, good quality.
- Pros: Inexpensive, versatile, easy install.
- Cons: Lower brand reputation compared to Packard or TEMCo.
Final Verdict: A solid budget-friendly dual capacitor. Check Price
Comparison Table
| Model | Type | Voltage | Best For | Price |
|---|---|---|---|---|
| TEMCo Industrial | Start | 440–480V | Large shop compressors | Check Price |
| Supco SPP6 | Hard Start | 330V | Small shop & portable units | See Price |
| Packard Dual | Start + Run | 370V | Two-stage compressors | Check Price |
| Genteq Run | Run | 370V | Continuous-duty compressors | View Price |
| Mars 1220 | Start | 250V | Small motors up to 5 HP | See Price |
| PowerWell PW-70/5 | Dual | 370V | General replacements | Check Price |
Frequently Asked Questions
How do I know which capacitor my compressor needs?
Check the label on your existing capacitor. It will list microfarads (µF) and voltage rating. Always replace with the same µF and equal or higher voltage.
Can I use a capacitor with a higher voltage rating?
Yes, you can go higher in voltage (e.g., replace 370V with 440V), but never lower. The microfarad rating must remain close to the original.
What happens if I install the wrong capacitor?
Using the wrong capacitor can prevent your compressor from starting, cause overheating, or even damage the motor windings.
Should I replace both start and run capacitors at the same time?
If one fails, it’s often smart to replace both, especially on older compressors, since they tend to wear out together.
Can I test a capacitor before replacing it?
Yes, using a multimeter with capacitance function. Compare the reading to the rated µF on the label—if it’s more than 10% off, replace it.
Conclusion
Capacitors may be small, but they are vital for your compressor’s health. Choosing the right one keeps your motor safe and ensures reliable operation. For most users, the TEMCo Industrial Start Capacitor is the best overall choice, while the Supco SPP6 is great for smaller units, and the Packard Dual Combo handles heavy-duty replacements perfectly.
If your compressor is struggling to start or run, don’t wait—replace the capacitor before the motor suffers damage. With the right match, your compressor will run like new again.