Thermostat for a refrigerator: temperature characteristics, application and replacement

The design and principle of operation of the thermostat

The main task of the thermostat is to maintain the optimal temperature in the refrigerator by automatically turning the compressor on/off.

The thermostat is a lever mechanism with a power lever and a contact system.

Visually, the device consists of a sealed tube, a switch knob and contacts. The tube for different thermostats may differ due to the level of the liquid phase of freon in it. It is often found curled into a spiral. This is necessary in order to ensure that, with such a length (with a small internal diameter), the tube fits tightly to the wall of the evaporator. The thermostat is located, most often at the top, where there is access to the control knobs and buttons.

The operating principle of the thermostat is as follows.

As the temperature decreases, the pressure inside the capillary tube will decrease. Under the influence of the main spring, the bellows corrugations will be compressed, and the power lever will rotate on its axis, causing the contacts to open. As the temperature increases, the pressure increases. Overcoming the resistance of the spring, the corrugations of the bellows will expand, and the lever will turn in the opposite direction, and the contacts will close. That is, the set temperature depends on the force of the spring; with a low force, the contacts will open and the temperature will be low; with a large force, the temperature will be high. The force depends on the handle, which, when turned, changes the tension of the spring.

Two-terminal thermostat

The following modifications are two-terminal:

• TAM133-1M-1
• TAM133-1M-3
• TAM133-1M-15
• TAM133-1M-20
• TAM133-1M-46
• TAM133-1M-64
• TAM133-1M-70
• TAM133-1M-75A

Such a thermostat has a simple circuit diagram, which assumes the presence of two terminals (3 and 4) for connection to the electrical wiring of the refrigerator.

The thermostat is connected to the compressor power supply circuit. The refrigeration chamber lighting circuit is powered directly from the power source and is completely independent of the thermostat. If the design of the refrigerator assumes the presence of additional electrical equipment, the power of which must be carried out independently of the compressor operating cycles (for example, an electric heater of the freezer door opening or an indicator lamp), then the circuits of such electrical equipment are connected similarly to the circuit of a lighting lamp (i.e., they are powered directly from the power source) . The inability to turn off additional electrical equipment using a thermostat is considered a disadvantage of such a scheme. To eliminate it, the design of some modifications of thermostats of the TAM133-1M series introduces an additional contact pair, which makes it possible to de-energize all electrical equipment of the refrigerator using the thermostat.

• L and N - Phase and neutral of the power supply network.
• C - Compressor.
• EL - Refrigerator compartment lighting lamp.
• SQ - Limit switch for the refrigeration chamber lighting lamp.

Replacement using the example of the Stinol refrigerator

Thermostat replacement diagram:

1. We de-energize the Stinol.
2. We remove decorative panels and other elements that interfere with access to the thermostat (often the installation location of the device blocks the lighting unit).
3. We remove the block with contacts and regulator. To do this, you will need to unscrew the screws or move the latches.
4. Disconnect the terminals with wires that go to the temperature controller.
5. Remove the bar securing the gas tube to the chamber wall.
6. We remove the broken thermostat from the refrigerator.
7. We install the tube of a working thermostat, giving it the required shape and pressing it.
8. We connect contacts.
9. We adjust the location of the device.
10. We install the components and panels in the reverse order.
11. Setting up the thermostat.
12. Checking the functionality of the refrigerator.

In the process of replacing an old thermostat with a new one, there is a possibility of damage to the device itself and other parts of the unit, so it is advisable to seek help from an experienced technician. If you want to do everything yourself, carefully watch the video instructions.

Where to find a refrigerator thermostat

To repair the thermostat, you first need to determine its location. The location of the device depends on the refrigerator model.

Inside

The thermostat is located in a small plastic box, which is located on one of the panels when you open the refrigerator. In order to see how the thermostat works, you need to unscrew the housing.

The principle is the same - the device is always located together with the handle responsible for switching temperatures.

Outside

As for the new models, the thermostats are not located in the refrigerator compartment. They are often located above the door, but may be elsewhere.

Table of temperature characteristics of Ranco K59 thermostats

Connection diagram for an intercom with an electromagnetic lock

The table shows the temperature characteristics of specific modifications of devices of the “K59” family, manufactured to order from the Electrolux group of companies (Electrolux, Rosenlew, Zanussi, etc.). Despite the fact that Stinol refrigerators use other modifications of Ranco K59 thermostats (in particular K59L1275, K59L1955), this information may be useful to Stinol refrigerator repair specialists. For example, if it is necessary to select a replacement for the original device.

The “heat” and “cold” columns of the table indicate the operating temperatures of thermostats at the extreme positions of the adjustment knob: “heat” - extreme counterclockwise position. “cold” is the extreme clockwise position.

The most common full-fledged replacement for Ranco devices is TAM133-1M thermostats manufactured by Orlex (Russia, Orel).

Video instructions on how to check the refrigerator compressor

Knowing how to check the compressor on a refrigerator is good in theory, but you also need to see the process itself. To do this, watch this video, where the master describes in detail checking the refrigerator with a tester and other methods.

Now you know how to check the refrigerator compressor yourself. You will be able to do this job if you have already dealt with electrical repairs and know how to use a multimeter. You should not take up testing if this is your first experience. The right decision would be to call a professional, especially if the refrigerator is under warranty.

Compressor

It is rightly called the heart of the refrigeration unit. Its task is to create a pressure difference between the discharge and receiving pipes to ensure reliable circulation of the refrigerant. Therefore, the functionality of the entire unit depends on how the compressor works. For household refrigerators, hermetically sealed housings are used, in which a compressor and an electric motor are placed. Special oil is used to lubricate moving parts.

Two compressors of a two-chamber refrigerator Atlant.

The electric motor is protected using a start-up relay, which connects the starting winding during startup and turns off the motor when it overheats. A filter drier is used to protect the compressor from moisture. The inverter compressor in the refrigerator, which is installed on modern models, can significantly extend the service life of the unit.

In addition, the use of an inverter reduces the noise level.

If desired, you can calculate the efficiency of the compressor. To do this, you need to record the work time T1 and the rest time T2. Then T1/(T1 + T2) = efficiency. For values ​​less than 0.2, the set temperature in the chamber must be adjusted downwards. If it is above 0.6, the door seal is faulty or it is skewed.

Magnetic tape on the refrigerator and its replacement.

Three-terminal thermostat without heating resistor

The following modifications are three-terminal without a heating resistor:

• TAM133-1M-2
• TAM133-1M-4
• TAM133-1M-5
• TAM133-1M-14
• TAM133-1M-47
• TAM133-1M-56
• TAM133-1M-57
• TAM133-1M-71
• TAM133-1M-72
• TAM133-1M-75
• TAM133-1M-75S
• TAM133-1M-91
• TAM133-1M-91S
• TAM133-1M-104

The schematic diagram of such a thermostat assumes the presence of three terminals (3, 4 and 6) for connection to the electrical wiring of the refrigerator.

The thermostat has two contact pairs. One of them (terminals 3 and 4) is used to ensure cyclic operation of the compressor, which maintains the temperature in the refrigerator compartment. The second (terminals 3 and 6) provides the ability to de-energize all electrical equipment of the refrigerator without the need to remove the power cord plug from the outlet. If the design of the refrigerator assumes the presence of additional electrical equipment, the power of which must be supplied independently of the compressor operating cycles (for example, an electric heater for the freezer door opening or an indicator lamp), then the circuits of such electrical equipment are connected similarly to the circuit of a lighting lamp (i.e., they are powered from terminal 3 of the thermostat) .

• L and N - Phase and neutral of the power supply network.
• C - Compressor.
• EL - Refrigerator compartment lighting lamp.
• SQ - Limit switch for the refrigeration chamber lighting lamp.

Three-terminal thermostat with heating resistor

The following modifications are three-terminal with a heating resistor:

• TAM133-1M-16
• TAM133-1M-19
• TAM133-1M-21
• TAM133-1M-28
• TAM133-1M-50
• TAM133-1M-55

The circuit of such a thermostat is identical to the previous one. The only difference is the presence of a heating resistor in the design. When the contact pair between terminals 3 and 4 is open, the current passing through the compressor winding powers the heating resistor. When this contact pair closes, it bypasses the resistor and it is de-energized. Thus, the heating resistor generates heat only during pauses in the compressor operation.

• L and N - Phase and neutral of the power supply network.
• C - Compressor.
• EL - Refrigerator compartment lighting lamp.
• SQ - Limit switch for the refrigeration chamber lighting lamp.
• R — Heating resistor as part of the thermostat.