Appliance Spares
Quick answer: A fridge thermostat (cold control) senses cabinet temperature and switches the compressor on and off to hold your set point. If your fridge runs non-stop, freezes food, won’t get cold, or never cycles, a failed thermostat is a prime suspect. We stock Samsung, LG and Haier fridge thermostats with same-day Sydney dispatch.
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What a fridge thermostat actually does
A fridge thermostat — also called a cold control — is the switch that decides when your compressor runs. In a mechanical fridge it’s a sealed bellows filled with gas connected to a thin capillary tube (sensor probe) that touches the evaporator or sits in the air stream. As the cabinet warms, the gas expands and closes the contacts, starting the compressor; as it cools to your dial setting, the gas contracts and opens the contacts, stopping it. That on-off cycling is what holds a steady 3–4°C. In newer fridges the same job is done electronically: a thermistor sensor feeds a temperature reading to the main control board, which switches the compressor. Either way, when the thermostat fails the fridge loses temperature control entirely — it either runs forever or never starts. Understanding which type you have decides how you test and what part you order.
Symptoms of a faulty fridge thermostat
A failing thermostat produces a small set of distinctive symptoms. Match yours to the table before buying anything — some of these point elsewhere.
| Symptom you observe | Most likely cause | What to do |
|---|---|---|
| Fridge runs constantly, never switches off | Contacts stuck closed (mechanical) or sensor reading high | Replace thermostat / test sensor |
| Food freezing in the fridge, milk slushy | Thermostat not opening contacts; compressor over-running | Replace thermostat |
| Fridge won’t get cold at all, compressor silent | Contacts stuck open / dead thermostat | Test & replace thermostat |
| Temperature swings wildly, won’t hold setting | Worn bellows or drifting thermistor | Replace thermostat / sensor |
| Dial does nothing across its range | Mechanical cold control failed | Replace thermostat |
| Both compressor AND lights dead | Power, not thermostat | Check supply / call tech |
A cold control that sticks closed makes the compressor run endlessly and over-freezes everything; one that sticks open leaves the fridge warm because the compressor never starts. If you can hear the compressor humming but temps are wrong, suspect the thermostat. If nothing runs at all, check power first.
Mechanical cold control vs electronic sensor
Knowing which system your fridge uses tells you exactly what to order and how to diagnose it.
| Mechanical cold control | Electronic temperature sensor | |
|---|---|---|
| How it works | Gas-filled bellows + capillary closes/opens a switch | Thermistor changes resistance, board reads it |
| Looks like | Dial unit with a thin copper/aluminium tube | Small bead/probe on a wire harness, no dial |
| Common on | Older top-mounts, bar fridges, chest freezers | Most fridges from ~2010 onward, French-doors |
| Test method | Continuity across contacts when warm/cold | Resistance check vs spec at known temp |
| Example part | LG 6930JB1003D, Samsung DA47-10160J | Haier sensor cable H0060402077 |
A mechanical cold control is a self-contained switch — no electronics — so you test it for continuity. An electronic sensor (thermistor) does no switching itself; it only reports temperature to the board, so you test its resistance. There’s also a third related part on many fridges: a defrost termination thermostat (bimetal), like the LG 6615JB2005A, which shuts off the defrost heater at a set temperature so the coils don’t overheat. Identify your type, then use the matching test below.
How to test (and safely bypass) a fridge thermostat
Unplug the fridge at the wall before touching any wiring — these are 240V mains appliances and the thermostat sits in the live circuit. If you’re not confident around mains wiring, stop and use a licensed technician (AS/NZS 3760).
For a mechanical cold control: pull the thermostat from its housing, leave the dial on its coldest setting, and put a multimeter on continuity across the two switch terminals. At room temperature the contacts should be closed (beep / near 0 Ω). Warm the sensor bulb in your hand or warm water — contacts should stay closed; chill the bulb (ice water) and they should open. No change across the range means a dead thermostat.
A quick bypass test confirms it: with the fridge unplugged, disconnect the two thermostat wires and join them with an insulated jumper, then plug in. If the compressor runs and the fridge cools, the thermostat — not the compressor — was the fault. Never leave it bypassed; it will freeze everything. For an electronic sensor, measure resistance against the maker’s spec at a known temperature; a wildly off or open reading means replace it.
Where the thermostat sits and how to replace it
On most fridges the thermostat lives inside the control housing — the plastic box on the fridge ceiling or upper rear wall that also holds the dial and light. To reach it: unplug at the wall, remove the dial knob, and unclip the housing (usually 1–3 screws plus tabs). You’ll see the capillary sensor tube routed to the evaporator or air duct — note exactly how it’s clipped and routed, because the replacement must sit in the same spot to read temperature correctly.
Swapping a mechanical cold control takes about 15–25 minutes: photograph the two wire terminals, transfer them one at a time to the new unit, re-route the capillary identically, and clip the housing back. For an electronic sensor like the Haier H0060402077, it’s a plug-and-clip job — disconnect the harness, fit the new sensor probe in the same well, reconnect. Restore power, set the dial mid-range, and check it cycles correctly over 24 hours. Don’t kink or stretch the capillary tube — a damaged one leaks its gas and ruins the new part.
Genuine fridge thermostats — find your part
Order by your fridge’s model number or the part number printed on the old thermostat. These are the genuine Samsung, LG and Haier fridge thermostats and sensors we keep in the Sydney warehouse. Link at least four below; if yours isn’t here, the Part Finder will match it.
| Part number | Fits | Link |
|---|---|---|
 DA47-10160J | Samsung SR366NTS, SR367NW, SR368NTS bimetal thermostat | |
 DA47-10160J | Samsung SR393NTS, SR394NW, SRS394NW, SR395NT bimetal thermostat | |
 DA47-10160J | Samsung RT41MBS1, RT45MB bimetal thermostat | |
 6930JB1003D | LG GR-332SF, GR-372SF, GR-432SF, GR482SFA fridge thermostat | |
 Defrost termination thermostat — see listing | LG GN-234SQA, GN-253SQA, GN-S303GCA defrost termination thermostat | |
 Fridge sensor cable — see listing | Haier 61213-A, 61214-A, 61220-A, 61222-A fridge sensor cable |
Not sure which one you need? Find your exact part with the Oz Part Finder.
Thermostat vs compressor: how to tell them apart
Before spending on a sealed-system repair, rule the thermostat in or out — it’s the cheaper, more common fault. The bypass test above is the deciding move: jump out the thermostat and if the compressor fires up and cools normally, the thermostat was the problem. If you bypass it and the compressor still won’t run (and you’ve confirmed power is reaching it), the fault is the compressor, start relay, or sealed system.
A compressor fault usually looks different from a thermostat fault: the compressor may hum then click off after a few seconds (a failing start relay/overload), get very hot, or stay completely silent even when called to run. A thermostat fault, by contrast, leaves a healthy compressor either running forever or never being switched on. Sealed-system and gas faults are not DIY work — they require a licensed refrigeration technician with a refrigerant handling licence under Australian regulations. Diagnose the thermostat first; it solves the majority of “temperature won’t hold” complaints.
What it costs in Australia (AUD)
Replacing a fridge thermostat yourself is one of the cheapest fridge repairs you can do. A genuine mechanical cold control or bimetal thermostat typically runs $25–$70 AUD, and an electronic sensor/probe is often $20–$55 AUD. Add a multimeter (around $25 if you don’t own one) and the job costs little more than the part.
Compare that to a callout: a technician visit in most Australian capitals is $120–$200 to attend, plus parts and labour, so a fitted thermostat from a tech commonly lands at $200–$350 AUD. A compressor or sealed-system repair is a different league — often $450–$900+, at which point an older fridge may not be worth fixing. Because the thermostat is inexpensive and the bypass test is conclusive, it’s almost always worth diagnosing and replacing it first. A good fridge is built to run for 12–15 years, so a $30 thermostat that buys you another decade of cold storage is far better value than scrapping a sound cabinet — which is why we keep genuine thermostats on the shelf rather than pushing a whole-unit replacement.
Frequently Asked Questions
Can a bad thermostat make a fridge too cold and freeze food?
Yes. If the cold-control contacts stick closed, the compressor never switches off and the fridge over-cools, freezing milk, lettuce and eggs. A drifting electronic sensor reading too warm does the same thing. Replacing the thermostat restores normal cycling.
Why does my fridge compressor run constantly?
The most common cause is a thermostat that won’t open its contacts, so the compressor never gets the “stop” signal. Other causes include a faulty door seal or defrost fault, but test the thermostat first with the bypass method above.
How do I know if it’s the thermostat or the compressor?
Bypass the thermostat with the fridge unplugged, then power up. If the compressor runs and cools, the thermostat was faulty. If it still won’t run with confirmed power, suspect the compressor, start relay or sealed system — a job for a licensed technician.
Is it safe to replace a fridge thermostat myself?
Yes for the thermostat itself, provided you unplug the fridge at the wall first and transfer the wiring carefully. It’s a low-voltage switch job, not gas work. If you’re unsure around 240V wiring, use a licensed technician per AS/NZS 3760.
What’s the difference between a cold control and a defrost thermostat?
A cold control switches the compressor to hold cabinet temperature. A defrost termination thermostat (like the LG 6615JB2005A) is a separate bimetal switch that cuts the defrost heater off at a safe temperature. They’re different parts doing different jobs.
How much is a fridge thermostat in Australia?
Genuine fridge thermostats and sensors typically cost $20–$70 AUD. Fitting one yourself avoids a $120–$200 technician callout, making it one of the best-value DIY fridge repairs.
Can I just leave the thermostat bypassed?
No. A bypass forces the compressor to run continuously and will freeze your food and waste energy. Use the jumper only as a momentary diagnostic test, then fit a correct replacement thermostat.
Frequently asked questions
Why does my fridge compressor run constantly?
The most common cause is a thermostat whose contacts won’t open, so the compressor never gets the stop signal. A faulty door seal or defrost fault can do it too, but test the fridge thermostat first — the bypass test is quick and conclusive.
Can a bad thermostat make a fridge freeze food?
Yes. If the cold-control contacts stick closed, the compressor never switches off and the fridge over-cools — slushy milk and frozen lettuce are the classic signs. A drifting electronic sensor reading too warm does the same thing. Replacing the thermostat restores normal cycling.
How do I tell if it’s the fridge thermostat or the compressor?
Do the bypass test: with the fridge unplugged, join the two thermostat wires with an insulated jumper, then power up. If the compressor runs and cools, the thermostat was the fault. If it still won’t run with confirmed power, suspect the compressor, start relay or sealed system.
How much does a fridge thermostat cost in Australia?
A genuine mechanical cold control or bimetal thermostat typically runs $25-$70, and an electronic sensor or probe $20-$55. Fitted by a technician it commonly lands at $200-$350 once the $120-$200 callout is included — while a compressor or sealed-system repair is often $450-$900 or more.
How long does replacing a fridge thermostat take?
A mechanical cold control swap takes about 15-25 minutes: unplug the fridge, unclip the control housing, photograph the two wire terminals, transfer them to the new unit and re-route the capillary tube exactly as before. Don’t kink the capillary — a damaged tube ruins the new part.
Is it safe to replace a fridge thermostat myself?
Yes for the thermostat itself, provided you unplug the fridge at the wall first and transfer the wiring carefully — it’s a switch job, not gas work. Sealed-system and refrigerant faults need a licensed refrigeration technician, and if you’re unsure around 240V wiring, use a licensed tech per AS/NZS 3760.
Related guides
- Find your exact part with the Oz Part Finder
- Hisense fridge not cooling? Evaporator fan & defrost diagnosis
- Haier fridge evaporator fan motor replacement
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