Why Wont My Dewalt Air Compressor Turn On

DeWalt Air Compressor Won’t Turn On? Here’s Why!

There are few things more frustrating than needing your tools and finding they won’t cooperate. If your DeWalt air compressor won’t turn on, it can halt your entire project. I understand this feeling well; I have faced it myself multiple times. This issue is common, and many possible reasons exist.

This article will help you figure out why your DeWalt air compressor might not be starting. We will look at common power supply problems, motor issues, and pressure system malfunctions. We will also cover essential safety checks and troubleshooting steps. By the end, you will have a clear path to diagnose and fix your compressor. Let’s get your DeWalt air compressor running again.

Takeaway

Always check the power supply first, including outlets, cords, and circuit breakers.
Thermal overload protection often stops the compressor from starting when it gets too hot.
Motor components like capacitors or brushes can fail, preventing the motor from spinning.
Issues with the pressure switch or unloader valve often prevent startup.
Regular maintenance and checks can prevent many common starting problems.

Why Won’t My DeWalt Air Compressor Turn On?

Your DeWalt air compressor will not turn on if it lacks proper electrical power, suffers from a tripped thermal overload, has a faulty motor component like a capacitor, or experiences issues with its pressure switch or unloader valve. Low voltage or an empty tank can also prevent startup.

Power Supply Problems: The First Check

When your DeWalt air compressor refuses to start, the first thing to check is its power source. Many times, the problem is not with the compressor itself but with the electricity it receives. This simple check can save you a lot of time and effort. I always start here when any electrical device fails to power up.

Outlet and Circuit Breaker Issues

Your wall outlet might be dead. Plug another device into the same outlet to test it. If the other device does not work, the outlet has no power. This often means a circuit breaker has tripped.

Go to your electrical panel. Find the breaker for the circuit your compressor is on. It might be in the “off” position or halfway between “on” and “off.” Flip it completely off, then firmly flip it back to the “on” position. If it immediately trips again, there is a short circuit or an overload somewhere on that line. You might need an electrician in this case. Ensure the circuit can handle the compressor’s amperage. A DeWalt air compressor draws a lot of power.

Extension Cord and Power Cord Damage

Many people use extension cords with their air compressors. An extension cord might be too long, too thin (not heavy-duty enough), or damaged. A small gauge cord causes a voltage drop, especially over long distances. This means the compressor motor does not get enough power to start.

Always use a heavy-duty, short extension cord rated for the compressor’s amperage. Inspect the compressor’s power cord itself. Look for cuts, frayed wires, or bent prongs. Damage to the cord can prevent power from reaching the motor. If the cord is damaged, replace it with an identical, correctly rated cord. Do not use a damaged cord; it is a fire hazard.

Tripped GFCI Outlet

Some garages or workshops have Ground Fault Circuit Interrupter (GFCI) outlets. These outlets protect against electrical shock. They trip easily if they detect a power surge or a ground fault. If your compressor is plugged into a GFCI outlet and it won’t start, press the “Reset” button on the outlet. If it trips again, there might be a fault in the compressor itself. Always use appropriate outlets for heavy-duty tools.

For more general troubleshooting tips on various appliances that won’t turn on, you might find some universal principles apply, such as those discussed when a Craftsman air compressor won’t turn on. The core principles of power delivery remain consistent across different brands and tools.

Thermal Overload Protector: A Safety Feature

Your DeWalt air compressor has a built-in safety feature called a thermal overload protector. This device monitors the motor’s temperature. If the motor gets too hot, the protector trips. It shuts off the compressor to prevent damage. This is a very common reason why your DeWalt air compressor won’t turn on after heavy use.

Why It Trips

The thermal overload trips for several reasons. The compressor might have run for a very long time without a break. It could be working in a hot environment. Low voltage can also make the motor work harder and heat up. A lack of proper ventilation around the motor causes heat to build up. This safety mechanism is there to protect your investment.

Resetting the Overload

Most DeWalt air compressors have a clearly marked red “Reset” button. This button is usually located near the power switch or on the motor housing. If your compressor suddenly stopped and won’t restart, check for this button.

Unplug the compressor: Always disconnect power before touching internal parts.
Allow it to cool: Wait at least 20-30 minutes for the motor to cool down.
Press the reset button: Firmly press the button. You might hear a click.
Plug it back in and try: Reconnect power and attempt to start the compressor.

If the thermal overload trips repeatedly, there is an underlying issue. The motor might be failing, or there could be a persistent low voltage problem. Overuse is a common cause, but frequent trips signal a deeper problem. Consider cleaning any dust or debris from the motor cooling fins. This helps dissipate heat.

Prevention of Overheating

Preventing the thermal overload from tripping saves you time. Ensure your compressor has good airflow around it. Do not operate it in direct sunlight on hot days. Take breaks during long periods of continuous operation. Allow the motor to cool down for 10-15 minutes after 30-45 minutes of heavy use. Proper ventilation and managed usage extend the life of your compressor. Regularly inspect the air intake filter too; a clogged filter can make the motor work harder.

Motor Starting Issues: The Core Problem

If your DeWalt air compressor gets power but the motor does not spin, you likely have a motor starting issue. These problems can be electrical or mechanical within the motor itself. The motor is the heart of your compressor.

Starting Capacitor Failure

Many air compressors, including DeWalt models, use a starting capacitor. This component provides an extra burst of electricity to help the motor overcome initial resistance and begin spinning. If the capacitor fails, the motor cannot get that initial “kick.” It might hum loudly but won’t start.

A faulty capacitor can look swollen, burst, or leak fluid. It can also fail internally without visible signs. Replacing a capacitor is a common repair. However, capacitors store a high voltage charge even when unplugged. Always discharge them safely before handling. If you are not comfortable with electrical work, get professional help.

Motor Windings or Brushes

The motor contains copper windings that generate the magnetic field needed for rotation. If these windings are damaged or shorted, the motor will not function. This often requires a motor rewind or replacement. This is a more serious and costly repair.

Some compressor motors use carbon brushes to transfer power to the rotating part (armature). Over time, these brushes wear down. Worn brushes prevent proper electrical contact. The motor might hum, spark, or simply fail to start. Checking and replacing carbon brushes is a common maintenance task for brushed motors. Not all DeWalt compressors use brushed motors, so check your model’s specifications. If your DeWalt air compressor isn’t starting, checking these motor components is essential.

Mechanical Binding

Sometimes, the motor itself is fine, but something is preventing it from turning. This is called mechanical binding. The pump or crankcase might have seized due to lack of oil or internal damage. Trying to turn the compressor pulley by hand (with the power off) can test for this. If it is stiff or won’t move, there is a mechanical problem.

Issues that cause mechanical binding often relate to the compressor’s pump or connecting rod. If the motor hums but does not spin, check if the pump can move freely. This might require disassembling parts of the compressor. Addressing mechanical binding often means looking at the internal pump components.

For insights into similar motor issues, you can review information on why portable air compressors might not be working. While it covers various brands, the principles of motor starting are often similar.

Pressure System Malfunctions: The Unseen Obstacles

The pressure system plays a critical role in your DeWalt air compressor’s ability to start. It involves the pressure switch and the unloader valve. If these components malfunction, the compressor’s motor will not activate correctly. This is often an overlooked area when troubleshooting a compressor that won’t turn on.

Faulty Pressure Switch

The pressure switch monitors the air pressure in the tank. It tells the motor when to turn on (when pressure drops below a set point) and when to turn off (when pressure reaches the maximum). A faulty pressure switch can prevent your DeWalt air compressor from starting.

Stuck “Open” or “Closed”: If the switch is stuck in the “open” position, it will not tell the motor to start, even if the tank pressure is low. If it’s stuck “closed” when the tank is full, it might prevent the motor from restarting properly.
Dirty Contacts: Internal electrical contacts within the switch can become dirty or corroded. This prevents proper electrical flow to the motor. You might be able to clean them, but often a replacement is needed.
Adjustment Issues: Sometimes, the pressure switch settings might be off. However, unless someone tampered with it, this is less likely to be the initial cause of a complete failure to start.

To test the pressure switch, you can sometimes bypass it momentarily (with extreme caution and knowledge of electrical systems) to see if the motor starts. However, it is safer to test for continuity with a multimeter. If the switch does not actuate correctly based on pressure, it needs replacement.

Stuck Unloader Valve

The unloader valve is a small, crucial component connected to the pressure switch. Its job is to release the residual air pressure from the compressor’s cylinder head and discharge tube when the compressor shuts off. This allows the motor to start freely against no pressure the next time it turns on.

If the unloader valve is stuck open, air continuously leaks, preventing pressure build-up. If it is stuck closed, the compressor tries to start against a full head of pressure in the cylinder. This makes the motor work too hard and often prevents it from starting at all. It might hum loudly and trip the thermal overload.

To check the unloader valve:

Turn off and unplug the compressor.
Press the schrader valve (like a tire valve) on the unloader tube. It is a small tube from the pump head to the pressure switch.
If air rushes out, it means the valve likely stuck closed. If it is stuck open, you would hear a continuous hiss when the compressor is supposed to be off.

A stuck unloader valve is a common cause of a DeWalt compressor motor humming but not starting. Sometimes, tapping the valve gently can free it. More often, it requires cleaning or replacement. Issues with pressure switches can also lead to scenarios where your DeWalt air compressor keeps running continuously, as it fails to register the target pressure.

Low Voltage and Electrical Supply Issues

Even if power is reaching your DeWalt air compressor, it might not be enough. Low voltage or insufficient amperage can prevent the motor from starting. Air compressor motors draw a significant amount of current, especially during startup.

Inadequate Circuit Amperage

Your DeWalt air compressor needs a dedicated circuit with sufficient amperage. For example, a large compressor might require a 20-amp or even a 30-amp circuit. Plugging it into a standard 15-amp household circuit shared with other devices can cause problems.

When the compressor tries to start, it draws a large surge of current. If the circuit cannot provide this, the voltage drops. This drop prevents the motor from getting the power it needs. It might hum and trip the circuit breaker. Ensure the electrical circuit matches the compressor’s requirements, typically found on its data plate or in the user manual.

Long or Thin Extension Cords

We discussed extension cords earlier regarding damage, but length and gauge are also critical. A very long extension cord, or one with a small wire gauge (like 16-gauge for heavy tools), causes a significant voltage drop. The further the electricity travels, the more resistance it encounters.

This voltage drop means the motor receives less than the required 120 volts (or 240 volts for larger models). It strains to start and might not succeed. Always use the shortest possible, heavy-duty extension cord. Look for cords labeled “12-gauge” or “10-gauge” for air compressors. A 10-gauge cord is thicker and handles more current over longer distances better than a 12-gauge.

Other Electrical Issues

Problems in your home’s wiring can also lead to low voltage. An old or faulty outlet could have loose connections. A shared circuit with too many other high-draw appliances could also be the culprit. If you suspect general house wiring issues, consult a qualified electrician. They can diagnose problems with your electrical supply.

Sometimes, a loose wire connection inside the compressor itself can cause a voltage drop at the motor. Check all wire terminals for tightness. Ensure no wires are pinched or corroded. Always unplug the unit before inspecting internal wiring. My own experience taught me that a simple loose connection can cause major headaches.

Understanding these electrical requirements is key to maintaining optimal performance and prevents the frustration of a compressor that won’t turn on due to power starvation.

Internal Component Failures and Maintenance

Beyond the common electrical and pressure system issues, internal mechanical failures can prevent your DeWalt air compressor from turning on. Regular maintenance is key to preventing these problems. Ignoring basic upkeep can lead to significant issues.

Pump Issues

The compressor pump is the heart of the system. It compresses the air. If the pump itself seizes or has significant internal damage, the motor might not be able to turn it. This can cause the motor to hum and trip its thermal overload.

Lack of Oil: For oil-lubricated compressors, a low oil level or contaminated oil can lead to excessive friction and pump seizure. Check your oil level regularly. Change the oil according to your DeWalt manual’s recommendations.
Bearing Failure: The pump’s bearings can wear out. This causes increased friction and resistance. The motor struggles to turn the pump. A seized bearing prevents the pump from rotating.
Piston/Cylinder Problems: Internal damage to the piston or cylinder can cause binding. This might be due to debris or wear.

Diagnosing pump issues often requires partial disassembly. If the motor hums but the pump doesn’t turn even with the unloader valve open, the pump is likely seized.

Check Valve Problems

The check valve sits between the pump and the air tank. It allows air to flow from the pump into the tank but prevents compressed air from flowing back into the pump when it’s off. If the check valve fails, it can prevent the compressor from starting.

If the check valve sticks open, air from the tank can flow back into the pump head. This means the motor tries to start against the full pressure of the tank, rather than an empty pump head. This makes it impossible for the motor to start, similar to a stuck unloader valve. You might hear air leaking back through the intake filter. A faulty check valve might also cause your Craftsman air compressor to not build pressure, indicating its importance in the pressure system.

Replacing a check valve is a relatively straightforward repair for someone with basic mechanical skills.

Air Intake Filter Clog

The air intake filter prevents dust and debris from entering the compressor pump. A severely clogged filter can restrict airflow to the pump. While this is less likely to cause a complete “won’t turn on” scenario, it can make the motor work much harder, leading to overheating and thermal overload trips. Over time, it can contribute to motor strain.

Regularly inspect and clean or replace the air intake filter. This is a simple maintenance task that promotes efficiency and prolongs compressor life. I replace my air filter every few months, depending on use, to keep my DeWalt running smoothly.

Proper maintenance, like cleaning your air compressor tank and checking for internal leaks, is vital for preventing these kinds of failures. A well-maintained compressor is a reliable compressor.

Troubleshooting DeWalt Specific Issues and Advanced Checks

DeWalt air compressors are known for their durability, but like all machines, they can develop specific issues. Some models might have unique diagnostic features or common failure points. Knowing about these can streamline your troubleshooting process.

DeWalt Model-Specific Diagnostics

Some DeWalt air compressors, especially newer or more advanced models, might have diagnostic codes or indicator lights. Refer to your compressor’s owner’s manual. The manual is your best friend for specific model information. It will often list common troubleshooting steps and error codes unique to your DeWalt unit. For example, some DeWalt models might display specific warnings that relate to their pressure systems. This can be similar to understanding what BLO means on a DeWalt air compressor for certain pressure-related issues.

If your model has an LCD display or a series of blinking lights, check what these patterns mean. They often point directly to the system that has failed, whether it is a pressure sensor, motor fault, or another component.

Start/Run Capacitor Testing

As mentioned earlier, a faulty capacitor is a common no-start issue. If you suspect the capacitor, you can test it with a multimeter that has a capacitance setting.

Safety First: Unplug the compressor.
Discharge: Safely discharge the capacitor using a resistor or insulated screwdriver with a plastic handle. Touch the two terminals of the capacitor with the screwdriver. You might see a spark.
Test: Set your multimeter to capacitance (uF). Connect the probes to the capacitor terminals. The reading should match the microfarad (uF) rating printed on the capacitor label. A significant deviation indicates a faulty capacitor.

If the capacitor is bad, replace it with one of the exact same specifications (uF rating and voltage rating).

Manual Start Test (Caution!)

In some cases, if the motor hums but does not start, you can briefly try to manually spin the fan or pulley by hand. This is highly dangerous and should only be attempted by experienced individuals with extreme caution. Make sure the power is off and unplugged before touching any part. Then, very briefly apply power while giving the fan/pulley a spin. If it starts, it confirms a capacitor or start winding issue. I strongly advise against this unless you are very familiar with electrical safety and motor operation. It is best to leave this to a professional.

Professional Help

If you have tried all the troubleshooting steps and your DeWalt air compressor still won’t turn on, it might be time to call a professional. Complex motor issues, internal pump failures, or persistent electrical problems require specialized tools and expertise.

Authorized DeWalt Service Centers: Check the DeWalt website for authorized service centers near you. These technicians are trained to work on DeWalt products and use genuine parts.
General Compressor Repair Shops: Many local tool repair shops can also diagnose and fix air compressors. Look for shops with good reviews and experience with various brands.

Investing in professional repair can save you money in the long run compared to attempting complex repairs yourself and potentially causing further damage. My philosophy is, know your limits, and when in doubt, call an expert.

Essential Safety Measures and Preventative Maintenance

Working with air compressors and electricity carries risks. Before attempting any troubleshooting or repair, prioritize safety. Additionally, regular preventative maintenance can significantly reduce the chances of your DeWalt air compressor failing to start in the first place.

Safety First: Always Disconnect Power

This is the most critical rule. Before inspecting any internal components, touching wires, or attempting any repair, always:

Unplug the compressor from the wall outlet.
Bleed all air from the tank. Open the drain valve and let all compressed air escape until the tank pressure gauge reads zero. This prevents accidental startup or sudden air release.

Failing to do so can result in severe electrical shock or injury from moving parts. I have seen too many close calls to emphasize this enough. Your safety is paramount.

Regular Maintenance Checks

A well-maintained DeWalt air compressor is less likely to surprise you with a no-start situation.

Drain the Tank Regularly: Condensation builds up in the air tank. This water can lead to rust, reducing tank capacity and potentially causing internal component issues. Drain the tank daily or after each use by opening the drain valve at the bottom.
Check Oil Levels (if applicable): For oil-lubricated compressors, check the oil level before each use. Add oil if needed. Change the oil according to the manufacturer’s schedule, typically every 100-200 hours of operation. Using the correct type of compressor oil is important.
Inspect Air Filter: Check the air intake filter regularly for dirt and debris. Clean or replace it as needed. A clogged filter makes the motor work harder, leading to overheating.
Check for Leaks: Listen for air leaks around fittings, hoses, and the pressure switch. Leaks make the compressor run more often, leading to premature wear and thermal overload trips. Use soapy water to find small leaks.
Inspect Cords and Hoses: Look for cracks, cuts, or wear on the power cord and air hoses. Replace damaged items immediately.
Clean the Unit: Keep the compressor clean, especially the motor and pump cooling fins. Dust and grime can act as insulation, causing overheating.

Proper Storage

When not in use, store your DeWalt air compressor in a clean, dry area. Protect it from extreme temperatures and moisture. If storing for extended periods, ensure the tank is drained and oil levels are correct. Proper storage prevents rust and keeps components in good working order for when you need them next.

By following these safety guidelines and performing routine maintenance, you extend the life of your DeWalt air compressor. You also minimize the chances of facing the frustrating problem of it not turning on when you need it most. A little effort now saves a lot of headaches later.

Frequently Asked Questions (FAQ)

What does it mean when my DeWalt air compressor hums but won’t start?

When your DeWalt air compressor hums but does not start, it often points to a faulty starting capacitor. The capacitor provides the initial burst of power to get the motor spinning. Other causes can be a seized pump, a mechanically bound motor, or a stuck unloader valve. The motor tries to start but cannot overcome the resistance.

How do I reset the thermal overload on my DeWalt compressor?

To reset the thermal overload, first unplug your DeWalt air compressor. Allow the motor to cool down for at least 20-30 minutes. Then, locate the red “Reset” button, usually near the power switch or on the motor housing, and press it firmly. Plug the compressor back in and try to start it.

Can a bad extension cord stop my DeWalt compressor from turning on?

Yes, a bad extension cord can definitely prevent your DeWalt compressor from turning on. If the cord is too long, too thin (small gauge), or damaged, it can cause a significant voltage drop. This means the compressor motor does not receive enough power to start properly, leading to humming or no action at all.

Why would my DeWalt compressor not turn on after I used it for a long time?

If your DeWalt compressor won’t turn on after extended use, it is highly likely that the thermal overload protector has tripped. Running for a long time causes the motor to overheat. The overload protector shuts it down to prevent damage. Allow it to cool and then press the reset button.

How can I tell if my DeWalt air compressor’s pressure switch is bad?

A faulty pressure switch can prevent your DeWalt compressor from starting. If the tank pressure is low but the compressor does not respond by turning on, the switch might be stuck. You might also hear constant air leaks if it is stuck open. Checking for continuity with a multimeter can help confirm if the electrical contacts are working correctly based on pressure.

Is it safe to try fixing my DeWalt air compressor myself?

You can safely troubleshoot simple issues like power supply, tripped breakers, or resetting the thermal overload. However, for internal electrical components like capacitors, motor windings, or pump issues, professional help is recommended. Always unplug the compressor and drain all air before any inspection to ensure your safety.

Conclusion

When your DeWalt air compressor won’t turn on, it can be frustrating. However, most common problems have straightforward solutions. I hope this comprehensive guide has given you the knowledge and confidence to diagnose the issue. We covered everything from basic power supply checks to more complex motor and pressure system problems. Remember to always start with the simplest solutions, like checking the power outlet and ensuring the thermal overload is not tripped.

Prioritize safety throughout the troubleshooting process. Always disconnect the power and drain the air tank before inspecting internal components. Regular maintenance, such as draining the tank, checking oil, and cleaning filters, will help keep your DeWalt air compressor running smoothly for years. If you’ve exhausted all these steps and the compressor still remains unresponsive, consider consulting a qualified professional or an authorized DeWalt service center. Getting your DeWalt air compressor back up and running means you can get back to your projects without delay.