Refrigerator Compressor Not Running: Start Relay and Diagnosis Guide
When a refrigerator stops cooling completely and the compressor never runs, the first thing to check is the start relay — not the compressor. The start relay is a $10–$20 component that plugs into the side of the compressor and provides the electrical kick to start it. Failed start relays are vastly more common than failed compressors, and misdiagnosing the relay as a compressor means spending $400–$600 (or buying a new fridge) unnecessarily. Do the shake test first.
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Common Symptoms
- Refrigerator is warm — neither compartment is cooling
- Compressor never starts (no hum, vibration, or cycling sounds from the back)
- A clicking sound from the back of the fridge every few minutes (compressor trying to start and failing)
- Fan is running inside the fridge but no cooling occurs
- Fridge light works and ice maker water valve clicks, but no cooling
Most Likely Causes
- 1
Failed Start Relay (Most Common — $10 Fix)
The start relay plugs into the compressor on the back lower section of the fridge. It provides a brief burst of current to the start winding to get the compressor spinning, then drops out once the run winding takes over. When the relay fails, the compressor can't start. You'll often hear a click every 2–5 minutes as the overload protector trips each time the stalled compressor overheats. The fix: pull the relay out, shake it near your ear. If you hear a rattle (broken internal contact), it's confirmed dead.
- 2
Overload Protector Failure
The overload protector is a thermal device that cuts power to the compressor if it overheats or draws too much current. A failed overload protector can either keep the compressor from starting at all, or cause repeated clicking as it trips and resets. The overload is usually integrated with the start relay on a relay/overload combination plug.
- 3
Compressor Thermal Cutout Tripped
Compressors have a built-in thermal cutout that protects against overheating. On a hot day or in a confined space with poor ventilation, the compressor may get hot enough to trip the thermal cutout. Unlike the start relay, this is a temporary condition — the compressor will restart after cooling down (30–60 minutes). If the fridge had been running fine and stopped on a hot day or after a power outage, this may be the cause.
- 4
Bad Relay on the Control Board
On newer refrigerators with electronic inverter compressors (common on Samsung, LG, and some GE models), the compressor is controlled by an inverter board or main control board. A failed relay or transistor on the board can prevent the compressor from receiving power even when the thermistor is calling for cooling. This requires testing the compressor's power supply directly.
- 5
Failed Compressor
A truly dead compressor — seized motor, blown windings, or cracked piston — is the most expensive failure. Test: disconnect the start relay and overload, and measure the compressor terminals with a multimeter. Common, Start, and Run terminals should all show 3–30 ohms between them. Any open reading (OL) indicates a blown winding — the compressor is dead. This is usually a machine-replacement decision.
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Quick DIY Checks
Always unplug the refrigerator before accessing the compressor compartment. The compressor body can be very hot during or after operation — allow time to cool before handling components in that area.
- 1Locate the compressor: unplug the fridge and pull it away from the wall. The compressor is a black dome-shaped component at the back bottom. The start relay is a small rectangular plug on the side of the compressor.
- 2Do the start relay shake test: firmly pull the relay straight off the compressor terminals (no screws, it's a friction fit). Hold it near your ear and shake it. If you hear a rattle — like a marble or broken piece inside — the relay is confirmed bad. A good relay is silent when shaken. Replace the relay ($10–$20). This test alone identifies the problem in the majority of no-cool compressor-not-running cases.
- 3Test the relay with a multimeter: set to ohms. Measure between the two large terminals (the ones that connect to the compressor). A good relay reads 0–10 ohms (near-zero resistance). An open reading (OL) means the relay contacts are failed open — replace it.
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Try Pro — $7.99/mo- 4Allow the compressor to cool if recently overheating: if the compressor body is very hot to the touch and the fridge was recently running, unplug it for 30–60 minutes and try again. Thermal cutout inside the compressor may have tripped from overheating. Ensure the fridge has 2+ inches of clearance on the sides and back for ventilation.
- 5Test the compressor windings (if relay tests good): unplug the fridge. Remove the relay and access the three compressor terminals (Common, Start, Run — usually labeled). Set multimeter to ohms and measure: Common-to-Start, Common-to-Run, and Start-to-Run. All three should read finite resistance (3–30 ohms). Any OL reading indicates a blown compressor winding — the compressor is failed and the machine should be replaced.
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Repair vs Replace
If the start relay is the problem, repair it — $10–$20 for the relay, and it's a 5-minute fix. If the compressor itself has failed, the economics change dramatically. Compressor replacement costs $400–$700 in parts plus labor, making it close to or exceeding the value of a mid-range refrigerator. For refrigerators over 8–10 years old with a dead compressor, replacement is usually the better financial decision.
Est. Repair Cost
$10–$25 for start relay; $400–$700 for compressor replacement
Est. Replacement Cost
$800–$2,500 for a new refrigerator
Recommended Tools & Parts
- Buy on Amazon →
Refrigerator Start Relay
Start relay for the compressor. Model-specific — search your refrigerator brand and model number. Whirlpool/Kenmore, GE, Samsung, and LG all have different relays.
$10–$25
- Buy on Amazon →
Start Relay and Overload Combination
Combined start relay and overload protector kit for refrigerators where both components are integrated in one plug.
$15–$40
- Buy on Amazon →
Digital Multimeter
For testing relay resistance and compressor winding resistance. Necessary for confirming whether the compressor or relay is the failed component.
$20–$40
Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.
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Frequently Asked Questions
- How do I do the refrigerator start relay shake test?
- Unplug the refrigerator and pull it away from the wall. Find the compressor at the lower back — it's a black dome. The start relay is a small rectangular plug on the side of the compressor. Pull it straight off (no tools needed — it's a friction fit). Hold it near your ear and shake it like a maraca. If you hear rattling — a broken piece or loose contact inside — the relay is dead. Silence means the relay passes the shake test and you should test it further with a multimeter, or look elsewhere for the failure.
- How do I tell if the compressor is dead or if it's just the relay?
- Replace the relay first — it's $10–$20 and takes 5 minutes. If the fridge starts cooling after the relay swap, you're done. If it still doesn't cool, test the compressor: with the relay removed, measure resistance between all three compressor terminal pairs (Common-Start, Common-Run, Start-Run). All should read 3–30 ohms. Any open reading (OL/infinity) is a blown winding — the compressor is dead. A compressor with all three readings in range but that still won't start may have internal mechanical seizure, which also means replacement.
- Why does my refrigerator click every few minutes but won't start?
- Clicking every 2–5 minutes is the classic sound of the overload protector tripping. Here's what's happening: the compressor tries to start, fails (because the relay is dead or the compressor is seized), draws high current, the overload trips to protect the compressor, the overload resets after a minute or two, and the cycle repeats. This clicking pattern, combined with no cooling, almost always means a failed start relay. Pull the relay and do the shake test.
- Can a refrigerator compressor be repaired?
- Compressors are hermetically sealed units — they are not user-serviceable. Repair means replacing the compressor, which costs $300–$600 in parts plus professional labor. On refrigerators under 5 years old still under warranty, this repair can be worthwhile. On older machines, the total cost often approaches or exceeds the price of a new mid-range refrigerator, making replacement the more practical choice.