Why Does My Craftsman Compressor Keep Tripping the Breaker? Troubleshooting Your 919.167310

It's a common frustration: you power up your Craftsman 919.167310 air compressor, and *click* – the circuit breaker trips, even with an empty tank. You're dealing with complex components like dual capacitors and no clear wiring diagram. Let's systematically break down the potential causes and solutions to get your compressor running again.

This guide will walk you through identifying capacitors, checking essential components like the check valve, understanding potential motor issues, and performing safe troubleshooting steps, all tailored to your specific model based on common user experiences and repair information.

Key Insights & Troubleshooting Highlights

• Capacitor Roles: The larger 136-150uF dual capacitor is likely the start capacitor, crucial for overcoming initial inertia. The 30uF capacitor is probably the run capacitor, aiding efficiency once running. Issues with the start capacitor are a common cause of startup breaker trips.
• Circuit Capacity is Crucial: Your compressor, often rated around 6 peak HP, can draw significant current during startup (potentially over 40A momentarily). A standard 15A household circuit may be insufficient. Testing on a dedicated 20A or 30A circuit is advisable.
• Beyond Capacitors: While capacitors are frequent culprits, the problem could also stem from faulty motor windings, a malfunctioning centrifugal switch, incorrect wiring, a stuck check valve, or even the breaker itself.

Demystifying the Capacitors and Wiring

Understanding the Dual Capacitor Setup

Single-phase motors, like the one in your compressor, need capacitors to create a phase shift for starting and running. Your setup with two distinct capacitor units (one single, one dual) is common in higher-horsepower compressors.

• Start Capacitor (Likely 136-150uF Dual Unit): This capacitor provides a large burst of energy to get the motor rotating from a standstill. It's typically connected to the motor's start winding via a centrifugal switch, which disconnects it once the motor reaches about 75-80% of its running speed. The dual nature and connecting resistor in your 136-150uF unit are part of this start circuit design, potentially offering a specific start characteristic or bleed-off function. A faulty start capacitor (or its associated resistor/switch) is a prime suspect for tripping the breaker immediately on startup.
• Run Capacitor (Likely 30uF Single Unit): This capacitor stays in the circuit while the motor is running, improving efficiency and power factor. Since you've already substituted this one with a known-good unit without success, it's less likely to be the primary cause of the *immediate* breaker trip, although its correct wiring is still essential.

Testing the Capacitors

Safety First: Always unplug the compressor and discharge capacitors before handling them. You can discharge them by carefully shorting the terminals with an insulated screwdriver or, more safely, using a resistor (like 10k Ohm, 5 Watt).

1. Visual Inspection: Look for bulging, leaking, or burn marks on both capacitor units and the resistor on the dual cap.
2. Multimeter Test (Requires Capacitance Function):
   • Set your multimeter to the capacitance (μF or MFD) setting.
   • Test the 30uF capacitor. It should read close to 30μF.
   • Test the 136-150uF dual capacitor. You may need to test each section if it has multiple terminals (often marked 'Herm' for Hermetic/Compressor, 'Fan', and 'C' for Common, though configurations vary). Check the total capacitance matches the rating. Also, test the resistor connecting the sections for continuity/correct resistance value (usually low ohms).
   • If any reading is significantly off (e.g., >10% deviation) or shows 'OL' (Open Loop/Infinite resistance), the capacitor or resistor is likely bad.

Wiring Concerns Without a Schematic

Finding an exact internal motor wiring schematic for older Craftsman models can be difficult. However, you can often trace the wires:

• The start capacitor typically connects to the motor's start winding and the centrifugal switch (usually located on the motor's end bell).
• The run capacitor connects to the run winding.
• Incorrect wiring after previous repairs or component replacements can cause shorts or improper operation, leading to breaker trips. Double-check connections against photos taken before disassembly or look for similar model diagrams online (e.g., searching for "Craftsman 6HP compressor motor wiring").
• Resources like Sears Parts Direct, Master Tool Repair, and Fix.com often have parts diagrams that can help identify component locations and general connections, even if they lack detailed internal motor schematics.

Exploring Other Potential Culprits

Insufficient Circuit Amperage

A 15A circuit breaker is often insufficient for compressors of this size. The initial startup current (inrush current) can easily exceed 15A, especially for a 6 peak HP motor. While it might run okay once started, that initial surge is enough to trip a lower-rated breaker.

• Recommendation: Try plugging the compressor into a dedicated 20A or even 30A circuit (if available and safe according to your home's wiring). If it starts without tripping on a higher-amperage circuit, your 15A circuit capacity is likely the primary issue.
• Extension Cords: If using an extension cord, ensure it's heavy-duty (at least 12-gauge, preferably 10-gauge) and as short as possible. Undersized or long cords cause voltage drop, making the motor work harder and draw more current.

The Check Valve: Location and Testing

The check valve is a one-way valve that prevents compressed air in the tank from flowing back into the compressor pump when it stops. If it's stuck open or leaking, the motor has to start against existing pressure (even a little residual pressure), significantly increasing the load and current draw.

Locating the Check Valve

• Follow the metal tube or hose coming from the compressor pump head to where it enters the air tank.
• The check valve is typically a brass fitting screwed into the tank at this connection point. It might have a small port on the side for the unloader line (a small tube often running to the pressure switch).

Testing the Check Valve

1. Unplug the compressor.
2. Drain all air from the tank.
3. Listen for Leaks (after running): If the compressor runs briefly before tripping, turn it off and listen carefully at the check valve. If you hear air hissing back *from the tank towards the pump*, the valve is leaking.
4. Manual Test:
   • Disconnect the tube coming from the pump head to the check valve inlet.
   • Try starting the compressor briefly. If it starts without tripping now, the check valve was likely causing excessive starting load.
   • You can also remove the check valve entirely (after ensuring the tank is depressurized) and inspect it. Try blowing through it – air should only pass in one direction (towards the tank). Clean any debris or replace it if faulty.

Motor and Internal Component Issues

If capacitors, wiring, and the check valve seem okay, the issue might be within the motor itself.

• Faulty Windings: A short circuit within the motor's start or run windings can cause an immediate high current draw. This often requires professional testing (megohmmeter) or motor replacement.
• Centrifugal Switch Malfunction: This switch disconnects the start capacitor/winding once the motor nears full speed. If it fails to open, the start circuit remains energized, drawing excessive current and tripping the breaker. If it fails to close when stopped, the motor may hum and fail to start. It's located inside the motor housing, usually on the end opposite the drive shaft.
• Bearing Issues: Seized or tight motor bearings increase friction, making the motor harder to turn and causing it to draw more current. Try rotating the motor shaft by hand (with power off) – it should turn relatively freely.
• Thermal Overload Protector: Most motors have an internal thermal protector (often a small button or automatic reset device) that shuts the motor off if it overheats. This device typically *doesn't* trip the main circuit breaker; it interrupts power within the motor circuit itself. If the motor runs for a short time then stops (without tripping the house breaker), the thermal protector might be activating due to overheating (caused by low voltage, bad bearings, etc.). However, your symptom is an *immediate breaker trip*, making this less likely the primary cause, though an underlying issue triggering the thermal protector could also contribute to high current draw.

Likelihood of Potential Faults Radar Chart

This chart provides a visual estimate of the relative likelihood of different issues causing your Craftsman 919.167310 compressor to trip the breaker immediately upon startup, based on common experiences with this type of equipment. Note that this is subjective and your specific situation may vary.

Systematic Troubleshooting Mindmap

This mindmap outlines a logical flow for diagnosing the breaker tripping issue with your Craftsman 919.167310 air compressor.

Visual Guide: Fixing a Craftsman Compressor Tripping Breakers

While diagnosing your specific issue requires hands-on testing, watching someone troubleshoot a similar problem can provide valuable insights. This video demonstrates fixing a Craftsman 30 Gallon / 6HP compressor (model 919.167311, very similar to yours) that was tripping breakers, focusing on a common failure point.

In this video, the user identified a faulty capacitor as the cause for the breaker tripping on startup. Although you've already tested substituting the 30uF capacitor, observing the diagnostic process, component locations (like the capacitor housing), and safety precautions can be helpful. Pay attention to how components are accessed and tested, which might give clues for checking your 136-150uF start capacitor or inspecting the wiring and centrifugal switch area.

Summary Table: Common Causes and Checks

Here's a quick reference table summarizing the potential issues discussed:

Frequently Asked Questions (FAQ)

References

• Craftsman 919167310 Air Compressor Parts Manual - Sears Parts Direct
• Craftsman 919.167310 Troubleshooting Guide - Manualzilla
• 30 Gallon 6HP 919.167310 wiring help - Master Tool Repair Forum
• 919.167310 at initial start up blows breaker - About Air Compressors Forum
• 10 Reasons Why Your Air Compressor Keeps Tripping The Breaker - All About Air Compressors
• Compressor Fix PDF (Specific to 919.167310 Capacitor) - My Tractor Forum

Recommended Reading

• How can I accurately test both start and run capacitors using a multimeter?
• What specific symptoms indicate a malfunctioning centrifugal switch in an air compressor motor?
• What are the requirements for circuit breaker size and wiring gauge for a 6 HP air compressor?
• Can I see a step-by-step guide for replacing the check valve on my Craftsman air compressor?