The refrigerator does not turn off after replacing the thermostat: 7 reasons and what to do

Have you replaced the thermostat in the refrigerator, but it still hasn’t started to turn off? The compressor runs non-stop, but the chambers are either arctic cold or insufficiently cooled? This problem is more common than it seems. In 60% of cases, it is not installation errors that are to blame, but hidden faults that appeared after intervention in the system. Even experienced technicians sometimes miss details when diagnosing.

In this article we will look at why the refrigerator does not turn off after replacing the thermostat - from a banal incorrect connection to rare fan breakdowns or freon leaks. You will learn how all possible reasons, for which the refrigerator does not turn off after replacing the thermostat - from a banal incorrect connection to rare fan breakdowns or freon leaks. You will learn how check the thermostat with a multimeterwhy the new sensor can lie, and what to do if the compressor is stuck in continuous operation mode. And at the end - a checklist for self-diagnosis and answers to frequently asked questions.

1. The thermostat is not connected correctly: typical installation errors

The first thing to rule out is incorrect connection of the new thermostat. Even if you followed the diagram, you might have missed some nuances:

• 🔌 The terminals are mixed up.. On most thermostats, the contacts are marked as 3 (common), 4 (for the compressor) and 6 (for the lamp). If you connect the compressor to 6, the refrigerator will work without stopping.
• 🔧 Contacts are not tightened. Poor contact leads to false operation or absence of a shutdown signal.
• 📏 Incorrect position of the capillary tube. If it is pressed against the chamber wall or bent, the sensor will show the wrong temperature.

How to check? Disconnect the refrigerator from the mains, remove the thermostat cover and check the connection with typical diagram (see table below). Make sure that the capillary tube lies freely on the evaporator without touching the plastic parts.

Note: Schemes may differ depending on the model. For accurate information, check the markings on the thermostat housing or in the instructions for the refrigerator.

2. The new thermostat is defective or does not fit the parameters

Even the original thermostat may be incompatible with your refrigerator model in terms of temperature range or control type. For example:

• 🌡️ Mismatch of temperature limits. The thermostat for Atlant MXM-2835 is designed to turn off when -12°C, and you installed an analogue with a threshold -16°C —the compressor will work longer.
• 🔄 Mechanical vs. electronic. Refrigerators often use electronic sensors rather than mechanical thermostats. Replacing them requires flashing the board. No Frost Electronic sensors are often used rather than mechanical thermostats. Replacing them requires reflashing the board.
• 🔋 Fault from the factory. According to statistics, 3-5% of thermostats have a defect in the capillary tube or contact group.

How to check the functionality of the thermostat?

1. Remove the thermostat and immerse its capillary tube in ice for 10 minutes.
2. Ring the contacts 3 and 4 with a multimeter in resistance mode. When cooling, they should open (show infinity).
3. Heat the tube with your hand - the contacts should close (resistance ~0 Ohm).

Which thermostats are most often counterfeited?

There are often counterfeit thermostats on the market K59 (for Stinol/Indesit) and Danfoss 077B6. The originals have laser markings on the case and a certificate in the packaging. Fakes are usually 10–15 grams lighter and have coarse threads on the nuts.

3. Freon leak: why the compressor runs “idle”

If after replacing the thermostat the refrigerator does not turn off, but at the same time poor freezing it is possible refrigerant leak. This is not directly related to the thermostat, but often appears after repair:

• 🔧 Damage to the tubes when dismantling the thermostat (for example, if the capillary tube is pinched or broken).
• 🕳️ Microcracks in the evaporatorthat have become depressurized over time.
• 🔥 Overheating when soldering (if you soldered the tubes without nitrogen protection).

Signs of a leak:

• The compressor works without stopping, but the chamber is warm.
• The condenser (grid at the back) is barely warm.
• Oil stains are visible on the tubes (freon leaves along with oil).

How to check? Touch filter drier (thin metal tube in front of the condenser). If it is cold, there is no freon. For accurate diagnosis, you need leak detector or a soap solution (applied to suspicious places - bubbles will appear if there is a leak).

4. Failure of the compressor or starting relay

Sometimes the thermostat has nothing to do with it - the fault compressor or its starting equipment. Common problems:

• 🔊 Motor jammed. The compressor hums, but does not pump freon (overheats and does not turn off).
• ⚡ Malfunction of the start relay. If the relay is “stuck”, the compressor will work constantly, even when the temperature is reached.
• 🔋 Interturn short circuit in the windings. Leads to overheating and activation of thermal protection (but not always).

How to diagnose:

1. Turn off the refrigerator, wait until the compressor cools down (1-2 hours).
2. Remove the starter relay (black box on the compressor) and check the resistance of the windings:

   Winding → Common wire: 15–30 Ohm
   Starting → Common: 20–40 Ohm
   Between windings: infinity (no short circuit)

3. If there is no resistance or they do not correspond to the norm, the compressor is faulty.

To check the relay, you will need a tester or a known working relay for replacement. If, when you turn on the refrigerator, the relay clicks, but the compressor does not start, it is faulty.

5. Problems with the fan or No Frost system

In refrigerators with No Frost continuous operation of the compressor may be associated with fan malfunction or defrosting. Reasons:

• 🌀 Fan icing. If the blades are covered with ice, the air does not circulate, and the thermostat “thinks” that the temperature has not been reached.
• 🔌 Open circuit of the fan. Check the power at the fan connector (should be 12V or 24V depending on the model).
• 🔥 The defrost heating element has burned out. In this case, the evaporator is covered with ice, and the system operates without stopping.

How to check:

1. Defrost the refrigerator for 12-24 hours.
2. After turning on, listen: if the fan does not make noise, it is not works.
3. Check the resistance of the defrost heating element (should be 20–60 Ohm).

V Samsung i LG s No Frost often fails defrost sensor (defroster). Its resistance should change when heating/cooling. If it is constant, the sensor needs to be replaced.

6. Malfunction of the electronic control module

In modern refrigerators (Liebherr, Bosch, Samsung with display) monitors the thermostat electronic control unit. If after replacing the thermostat the refrigerator does not turn off, it is possible:

• 🖥️ Firmware failure. For example, after a power outage.
• 🔌 Oxidation of contacts on the board or in the sensor connectors.
• 🔥 Failure of the triacthat control the compressor.

Signs of a problem with the module:

• The display shows an error (for example, E1, F2 —see code table).
• The compressor turns on and off immediately (cyclically).
• Does not respond to changes in temperature settings.

What to do:

1. Reset the settings: turn off the refrigerator for 5 minutes, then turn it on.
2. Check the voltage at the output of the board to the compressor (should be 220V during operation).
3. If you have soldering experience - inspect the board for burnt elements (blackened resistors, swollen capacitors).

Check the voltage on the board (220V)

Inspect the board for burnt elements

Reset errors by turning off the power

Ring the sensor circuits

Update the firmware (if available)-->

7. External factors: why the refrigerator does not turn off “due to the fault” of the user

Sometimes the problem lies not in the technology, but in operating conditions:

• 🌡️ High temperature in room (above 30°C). The compressor physically cannot cool the chamber to the set temperature.
• 🚪 Frequent opening of the door or a damaged seal. Leads to a constant flow of warm air.
• 🍖 Overload with food. If the refrigerator is filled to capacity, the air does not circulate and the sensor does not “see” the real temperature.
• ☀️ Direct sunlight on the back wall. The condenser overheats and the cooling efficiency drops.

How to check:

1. Measure the room temperature If higher 28°C - Move the refrigerator to a cool place.
2. Check the door seal with a sheet of paper: if it falls out, it needs replacement.
3. Defrost the refrigerator and leave it empty for 12 hours. If it starts to turn off, the problem is in the load.

B. refrigerators No Frost do not place food close to the back wall - this blocks air circulation and causes the compressor to work without stopping.

Checklist: what to do if the refrigerator does not turn off after replacing the thermostat

Follow this algorithm to find the reason:

Check the correct connection thermostat (diagram)

Test the thermostat with a multimeter (cold/hot test)

Inspect the compressor and start relay

Check the fan and No Frost system (if any)

Eliminate leakage freon (leak detector, soap solution)

Check the electronic module (voltage, errors)

Eliminate external factors (room temperature, seal)-->

If all points are checked, but the problem remains, it is most likely faulty compressor or electronic unit. In this case, professional diagnostics will be required.

FAQ: Frequently asked questions

Is it possible to temporarily operate the refrigerator if it does not turn off?

Short-term (1-2 days) - yes, but only if the compressor does not overheat (the housing must be warm, but not hot). Long-term operation without shutting down will lead to:

• Overheating and failure of the compressor.
• Increased power consumption (up to 2-3 times).
• Icing of the evaporator (in models No Frost).

If the refrigerator freezes poorly, it is better to turn it off and defrost it to avoid freon leakage.

Which thermostat is better to buy: an original or an analogue?

Original thermostats are more reliable, but are often 2-3 times more expensive. Analogs (for example, Danfoss, Ranco) are suitable if:

• The model and temperature range match.
• There is a warranty from the seller (minimum 6 months).
• Capillary tube of the same length and diameter.

For refrigerators Samsung and LG it is better to take the original - their systems are sensitive to sensor parameters.

How much does it cost to repair if the refrigerator does not turn off?

The cost depends on the reason:

Problem	Repair price (RUB)
Replacing the thermostat	1 500–3 000
Repairing the compressor	3 500–6 000
Refilling freon	2 500–5 000
Replacing the electronic module	4 000–8 000

Prices are indicated without accounting for spare parts. In regions they may differ by 20–30%.

Can the refrigerator not turn off due to power surges?

Yes. When voltage surges are higher 240V:

• The starting relay or triac on the board burns out.
• The electronic thermostat fails (in models with a display).
• The compressor “sticks” in operating mode.

Solution: connect the refrigerator via stabilizer voltage (for example, Resanta ASN-1000).

What to do if the refrigerator is new and does not turn off immediately?

Possible reasons:

• Transport modeIn some models (Liebherr, Bosch) you need to manually turn it off. demo mode (see instructions).
• Defective compressor. Return the refrigerator under warranty.
• Incorrect installation. If the refrigerator is not level or close to the wall, the condenser overheats.

Do not try to repair a new refrigerator yourself - this will void the warranty.