Refrigerator Clicking But Not Starting – A Technician’S

Hearing a rhythmic click coming from the back of your appliance is a classic sign of a refrigerator clicking but not starting. This sound usually indicates that the compressor is trying to kick on but is being thwarted by an electrical or mechanical failure.

As a technician, I see this issue most often when a specific component in the start circuit fails. Understanding the relationship between the relay and the compressor is the first step to saving your food from spoiling.

The clicking sound is actually a safety mechanism at work. It is the sound of the overload protector cutting power to the compressor to prevent a catastrophic electrical fire or motor burnout.

Why Your Refrigerator Clicking But Not Starting Requires Immediate Attention

When you encounter a refrigerator clicking but not starting, the clock is ticking on your perishable goods. The compressor is the heart of the cooling system, responsible for circulating refrigerant through the evaporator and condenser coils.

If the compressor fails to engage, the internal temperature will rise rapidly. Most modern units will attempt to restart every few minutes, leading to the repetitive clicking sound you hear.

Ignoring this sound can lead to further damage. Continuous attempts to start a seized compressor can overheat the wiring or damage the digital inverter control board in high-end models.

Understanding the Relay-Overload Assembly and PTC Thermistor

The most common culprit in this scenario is the relay-overload assembly. This small device is mounted directly onto the side of the compressor and is responsible for providing the initial “kick” to get the motor spinning.

Inside many of these assemblies is a PTC thermistor. This is a ceramic disk that increases in resistance as it heats up, effectively cutting out the start winding once the motor reaches about 75% of its rated speed.

If the PTC thermistor cracks or burns out, the circuit stays open. This prevents the compressor from getting the torque it needs to start, resulting in a hum followed by a click from the overload protector.

• Unplug the refrigerator before attempting any repairs.
• Remove the rear access panel to locate the compressor.
• Pull the relay-overload assembly off the compressor terminals.
• Shake the relay; if it rattles like a box of broken glass, the internal ceramic disk is shattered.
• Check for visible burn marks or a distinct “burnt electronics” smell.

The Role of the Start Capacitor and Run Capacitor

Many modern refrigerators utilize a start capacitor to provide an extra boost of electrical energy during the startup phase. This component stores electricity and releases it in a high-voltage burst to overcome the initial inertia of the compressor motor.

If the start capacitor fails, the compressor may hum but will lack the power to turn over. This leads to high amperage draw, which triggers the overload protector to click off.

Some units also feature a run capacitor. While the start capacitor is only active for a second, the run capacitor stays in the circuit to improve motor efficiency and power factor.

A failing run capacitor can cause the compressor to run hot or stall under load. In either case, the result is often a refrigerator clicking but not starting as the system tries to protect itself.

• Visually inspect capacitors for bulging, leaking fluid, or scorch marks.
• Use a multimeter set to the capacitance (MFD) setting to verify the rating.
• Always discharge a capacitor with a high-ohm resistor before handling to avoid a dangerous shock.
• Compare your multimeter reading to the microfarad rating printed on the capacitor casing.

Diagnosing the Hermetic Compressor and Motor Windings

If the relay and capacitors check out, the problem may lie within the hermetic compressor itself. This is a sealed unit containing both the motor and the pump mechanism, meaning it cannot be serviced internally.

The motor inside has two main sets of compressor motor windings: the start winding and the run winding. If either of these windings is “open” (broken) or “shorted” to the metal casing, the compressor will not run.

You can diagnose this using a multimeter continuity test. By testing the three pins on the side of the compressor (Common, Start, and Run), you can determine the health of the internal motor.

• Set your multimeter to the lowest Ohms setting.
• Measure the resistance between the Run and Common pins.
• Measure the resistance between the Start and Common pins.
• The sum of these two readings should approximately equal the resistance between the Start and Run pins.
• Test each pin against the compressor’s metal housing to check for a ground short.

If you find that the windings are intact but the compressor still won’t start, it may be mechanically seized. This condition is often referred to as locked rotor amperage (LRA), where the motor draws maximum current because it cannot move.

Troubleshooting the Digital Inverter Control Board

In newer, high-efficiency refrigerators, the traditional start relay is replaced by a digital inverter control board. These systems vary the speed of the compressor rather than just turning it on and off.

An inverter board converts standard AC power into three-phase DC power. If the board’s power transistors or capacitors fail, it may send incorrect signals to the compressor, causing a clicking sound.

Diagnosing an inverter system is more complex. You often have to check for specific DC voltage outputs at the compressor harness while the unit is powered on.

• Check for diagnostic LED lights on the main control board or inverter board.
• Look for a specific flash code that corresponds to a compressor start failure.
• Ensure the communication signal from the main board is reaching the inverter.
• Verify that the incoming AC voltage to the board is stable and within range.

Step-by-Step Guide to Fixing the Issue

When you are faced with a refrigerator clicking but not starting, follow this logical progression to isolate the fault. This sequence moves from the most common and least expensive parts to the most complex.

1. Power Cycle the Unit: Unplug the fridge for 10 minutes to allow the system pressures to equalize and the control board to reset.
2. Clean the Condenser Coils: Heavy dust buildup causes the compressor to overheat, which can trigger the overload protector prematurely.
3. Inspect the Start Relay: Remove the relay from the compressor and perform the shake test or check for continuity across the terminals.
4. Test the Capacitors: Use a multimeter to ensure the start and run capacitors are holding and releasing the correct charge.
5. Check Compressor Continuity: Test the three compressor terminals for proper resistance and ensure there is no short to ground.
6. Measure Voltage: Verify that the relay is actually receiving 120V AC from the thermostat or control board when the cooling cycle is called for.

If the relay is good and the compressor windings are healthy, but the unit still clicks, the compressor is likely mechanically stuck. In some cases, a “hard start kit” can provide enough extra torque to break a seized compressor loose, but this is often a temporary fix.

Frequently Asked Questions

Is it worth replacing a compressor that is clicking?

Replacing a compressor is one of the most expensive appliance repairs. If the refrigerator is more than 8-10 years old, the cost of the part and the labor of a certified sealed-system technician often exceeds the value of the unit.

Can a dirty condenser cause the clicking sound?

Yes, if the condenser coils are covered in pet hair or dust, the refrigerant cannot shed heat effectively. This causes the compressor to run extremely hot, eventually tripping the overload protector as a safety measure.

What does a “hard start kit” do?

A hard start kit is a combination of a powerful capacitor and a relay. It is designed to provide a massive electrical boost to help a struggling or aging compressor overcome mechanical friction during startup.

How do I know if my start relay is bad?

The easiest way to tell is the shake test; a rattling sound almost always indicates a failed PTC thermistor. Additionally, you can use a multimeter to check for continuity between the plug-in holes on the relay.

Why does my fridge click but the lights are still on?

The lights and the cooling system operate on different circuits. The clicking indicates a failure in the high-current compressor circuit, while the low-current logic and lighting circuits remain functional.

Dealing with a refrigerator clicking but not starting can be frustrating, but most of the time, it is a simple fix involving the start components. By systematically testing the relay, capacitors, and motor windings, you can determine whether a $20 part or a new appliance is in your future.