If your refrigerator is silent or clicking and not cooling, do not assume the compressor is finished. The most common cause by a wide margin is the small start relay that sits on the compressor terminal — a part that costs about as much as lunch and takes minutes to change.
Unplug the refrigerator before removing any rear panel. Mains voltage is present at the compressor terminals and the relay, and a capacitor may hold a charge after the plug is removed. If you are not confident working near mains voltage, diagnose only as far as step 3 and then call a technician.
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1. Confirm the fridge has power
Before anything technical, confirm the unit is receiving power and the control board is calling for cooling.
- Interior light: no light at all means no power to the unit.
- Outlet test: plug a lamp or charger into the same outlet. Kitchen outlets are frequently GFCI — press reset.
- Breaker: check the panel for a tripped circuit.
- Control panel: confirm the fridge is not in a demo or showroom mode, and check for a fault code.
2. Listen and feel for the compressor
Locate the compressor — the black dome-shaped unit at the lower rear of most fridges. Then watch for one of three patterns.
| What you observe | What it means | Next step |
|---|---|---|
| Silent, cold, no vibration | No power reaching the compressor | Check the board and the overload |
| Click, brief hum, click | Start relay or capacitor failed | Steps 3 and 4 |
| Humming but very hot, not cooling | Compressor running but system fault | Check coils; then sealing system |
| Trips the breaker when it starts | Short circuit or seized compressor | Stop — call a technician |
“Click — hum — click” repeated every few minutes is the classic signature of a start relay that has failed. The compressor tries to start, draws locked-rotor current, the overload heater trips, and the cycle repeats. It is a distressingly common failure and almost always a cheap fix.
3. Test the start relay — the highest-value five minutes
Unplug the fridge. Pull the plastic relay off the compressor terminal. Depending on the type, you will find either a PTC disc or a mechanical contact inside.
- Shake test. Shake the relay next to your ear. A healthy solid-state relay is silent; a broken one rattles because the internal disc has shattered.
- Smell test. A burnt electrical smell means the relay has failed.
- Visual test. Look for blackening, cracked plastic, or a burnt terminal.
- Replacement. Buy by compressor model number, not by fridge brand. They are typically $10–$30.
Because the relay is the cheapest and most likely failure, replacing it on spec — rather than testing further — is a reasonable approach on a fridge that is clicking.
4. Test the run capacitor
Some models use a run capacitor alongside the relay. A weak capacitor lets the compressor start poorly or not at all, and it often looks perfectly fine.
- Discharge it safely before testing — a capacitor can hold a charge.
- Set a multimeter to capacitance (µF) and compare the reading to the value printed on the can. A reading well below spec means replace it.
- A bulged top or leaking body is a definite failure.
- Cost: usually $10–$25.
5. Test the compressor windings
If the relay and capacitor are good and power reaches the compressor, test the motor windings. You are looking for continuity between the common, start and run terminals, and infinite resistance to ground.
| Test | Healthy reading | What a bad reading means |
|---|---|---|
| Common to run | Low resistance (a few ohms) | Open = winding failed |
| Common to start | Slightly higher (a few to tens of ohms) | Open = winding failed |
| Start to run | Sum of the two above | Vastly different = shorted |
| Any terminal to case | Infinite (no continuity) | Continuity = grounded, replace the unit |
If any terminal shows continuity to the compressor case, the unit is electrically grounded and unsafe. Unplug it, stop, and do not attempt to run it. A grounded compressor is a replacement, not a repair.
What each result means
| Finding | Diagnosis | Action |
|---|---|---|
| Relay rattles or smells burnt | Start relay failed | Replace — $10–$30, DIY |
| Capacitor below spec | Run capacitor weak | Replace — $10–$25, DIY |
| Windings open or shorted | Compressor failed | Replace the unit |
| Continuity to case | Grounded compressor | Unplug and replace — unsafe |
| Relay good, windings good, still no start | Control board or overload | Technician diagnosis |
| Compressor runs but no cooling | Sealed system fault | Technician with gauges |
Click-hum-click plus a rattling relay is the most common refrigerator failure there is, and it is a $15 part with a five-minute fit. Test the relay first, then the capacitor, then the windings. If the windings or the sealed system are at fault, put the money toward a new unit.
Frequently asked questions
Before you condemn the compressor
| Check | How | Meaning if it fails |
|---|---|---|
| Power at the outlet | Plug in a lamp | Supply problem |
| Thermostat setting | Turn the dial | Set to off or failed thermostat |
| Door switch | Press it manually | Compressor inhibited |
| Defrost timer | Advance the cam | Stuck in defrost |
| Start relay | Shake and measure | Failed relay |
| Overload protector | Continuity | Tripping prematurely |
| Compressor windings | Resistance across pins | Compressor failed |
A silent refrigerator is far more often a cheap electrical fault than a dead compressor. The compressor only runs when the control circuit tells it to, and that circuit passes through the thermostat, the door switch, the defrost timer and the start relay before it reaches the windings. Work through the chain in order and the fault is usually found well before the compressor.
Check power, then the thermostat, then the defrost timer, then the relay and overload, and test the windings last. In practice the compressor is the least likely culprit in a no-run condition, and it is by far the most expensive part to replace.
When to stop and call a technician
Compressor replacement is the point where DIY stops making sense. The circuit contains refrigerant under pressure, needs recovery and recharge equipment, and the work is regulated in many places, so the practical boundary is the sealed system.
Replacing the start relay, checking the capacitor and testing the overload are all reasonable DIY steps. Once you have confirmed the start device is healthy and the compressor still does not run, the remaining possibilities are internal, and that is a job for someone with the tools and the licence.
