A decrease in cooling efficiency or, conversely, excessive freezing of food in the refrigerator often indicates a malfunction of the thermostat. The model thermostat K-59 is one of the most common components installed in household refrigerators of various brands. Its main task is to monitor the temperature inside the evaporator and control the start of the compressor. When this mechanism fails or its calibration is lost, the entire freezing cycle is disrupted.
An understanding of the operating principle of this unit is necessary for every owner of household appliances who wants to extend the life of the unit. Adjusting the thermostat requires caution, since incorrect actions can lead to breakdown of the compressor or spoilage of products. In this article we will analyze all the nuances of diagnosing, setting and replacing the element so that you can independently restore the climate in your refrigeration chamber.
The design and principle of operation of the K-59 thermostat
Thermostat K-59 is an electromechanical device that responds to changes in the temperature of the refrigerant in the evaporator. Inside the housing there is a bellows tube filled with gas or liquid with a certain expansion coefficient. When heated, the gas expands, creating pressure on the membrane, which opens or closes the electrical contacts.
It is important to understand that this type of regulator belongs to the category normally closed. This means that at normal temperatures the contacts are closed and current flows to the compressor. When the temperature reaches a predetermined threshold, the pressure in the bellows drops and the contacts open, stopping the motor. If this cycle is broken, the refrigerator stops turning off or does not turn on at all.
The K-59 design includes an adjusting screw that changes the tension of the spring acting on the contacts. Turning this screw allows you to shift the temperature response range. Also on the case there is often an additional adjustment for setting the contact opening temperature, which affects the duration of the pause between switching on.
⚠️ Attention: Before starting any work on the electrical components of the refrigerator, be sure to disconnect the device from the mains. Working under voltage is deadly and can lead to electric shock or short circuit.
Many users confuse a thermostat with a temperature sensor, but in older and many modern models it is a mechanical switch. Its reliability is high, but over time, the characteristics of the freon in the bellows may change, and the contacts may burn, which requires intervention.
Symptoms of malfunction and the need for adjustment
Before proceeding with complex manipulations with tools, it is necessary to accurately diagnose the problem. Often, symptoms indicating the need K-59 adjustmentscan be confused with a freon leak or a compressor malfunction. The key sign is the incorrect behavior of the refrigerator in different operating modes.
Let's consider the main signs that require intervention:
- ❄️ The refrigerator works without interruption, forming a “fur coat” on the back wall, but the temperature in the chamber does not drop below +10°C.
- 🔊 The compressor starts very rarely, and the products in the upper part of the chamber begin to thaw, although everything below is frozen.
- 💡 The light in the chamber is constantly on, even when the motor should be resting, which indicates sticking contacts.
- 🌡️ The temperature in the chamber does not correspond to the position of the control knob (for example, at maximum cold it is barely cool).
If you notice that the refrigerator has started to turn on too often, this may indicate that it is temperature differential too small. In this case, the motor does not have time to cool down and gain the required torque, which leads to its rapid wear. Conversely, too infrequent switching on leads to defrosting of the contents.
It is also worth paying attention to the condition of the door seal. If it is leaking warm air, the thermostat will constantly require cooling, creating the illusion that it is faulty. Checking the chamber for tightness is the first step before adjusting the mechanics.
Preparing for adjustment: tools and safety
To properly adjust the thermostat K-59 you will need a minimum set of tools, which can be found in the garage of most home craftsmen. The main rule is a clean and dry workplace, since moisture on the contacts is unacceptable.
You will need the following items:
- 🔧 Screwdrivers (Phillips and flat) for removing covers and accessing the thermostat.
- 🌡️ External thermometer for monitoring the actual temperature inside the chamber.
- 🔌 Multimeter or indicator screwdriver to check the presence of voltage and integrity of contacts.
- 🧤 Dielectric gloves to protect hands when working with electrical equipment.
Before starting work, the refrigerator must be completely defrosted. The presence of ice on the evaporator will distort heat transfer, and you will not be able to correctly evaluate the operation of the thermostat. It is also necessary to provide access to the rear wall of the fridge compartment, where the unit is usually located.
☑️ Preparation for adjustment
Pay attention to the markings of the device. Thermostats K-59 can have various modifications, differing in the length of the capillary tube and temperature range. Make sure that you are working with exactly the model that is installed in your unit, since the adjustment parameters may differ.
Step-by-step instructions for setting the temperature mode
The process of adjusting the thermostat K-59 consists of changing the tension springs using a special adjusting screw. This screw is usually hidden under a plastic handle or plug on the thermostat housing. It can be accessed after removing the temperature control knob.
Perform the steps in the following sequence:
- Remove the temperature control knob by carefully pulling it towards you.
- Find the adjusting screw inside the hole or under the removable one panel.
- Make a mark with a marker on the original position of the screw to be able to return to the factory settings.
- Turn the screw clockwise to decrease the temperature (increasing cold) or counterclockwise to increase it.
One full turn of the screw usually changes the response temperature by 2-3 degrees Celsius. Don't make sudden movements. After each half-turn, you need to let the refrigerator run a full cycle (turn on and off) to evaluate the result.
⚠️ Attention: Excessive tightening of the screw may cause the thermostat contacts to stop opening. The compressor will operate continuously, which will cause it to overheat and possibly fail in a few hours.
If adjustment with the standard screw does not produce results, the factory settings of the second screw, which is responsible for the opening temperature, may have been reset. Access to it is often closed with a seal or requires partial disassembly of the thermostat housing, which is not recommended to do without experience.
What to do if the screw spins endlessly?
If you feel that the screw is spinning without resistance and the temperature does not change, the thread may be broken or the adjustment mechanism inside the housing may be broken. In this case, only replacing the thermostat with a new one will help.
Temperature control and standard table
After carrying out adjustment work, it is necessary to make sure that the temperature in the refrigerator compartment complies with food storage standards. To do this, use an external thermometer placed in a glass of water on the middle shelf.
Optimal indicators for different zones of the refrigerator:
| Storage area | Optimal temperature (°C) | Acceptable range | Type of products |
|---|---|---|---|
| Top shelf | +4...+6 | +2...+8 | Ready food, drinks |
| Middle shelf | +2...+4 | 0...+5 | Dairy products, sausages |
| Lower shelf | 0...+2 | -1...+3 | Raw meat, fish |
| Door compartments | +5...+8 | +4...+10 | Sauces, medicines, eggs |
If after adjusting the thermostat K-59 the indicators do not fall within these limits, there may be a problem The problem lies not in the settings, but in a refrigerant leak or compressor malfunction. The thermostat cannot create cold, it only controls the system.
Measurements should be carried out during the day. Record the minimum and maximum values to understand the amplitude of the vibrations. If the temperature spread is too large (more than 5-6 degrees), this may indicate improper operation of the thermostat or problems with air circulation.
Diagnostics of the electrical circuit and replacement of the component
In cases where the adjustment does not help, or the thermostat is completely out of order, it needs to be replaced. Before purchasing a new part, be sure to check the integrity of the electrical circuit of the old device. To do this, use a multimeter in dial mode.
Testing algorithm:
- 🔌 Disconnect the wires from the thermostat contacts.
- ⚙️ Switch the multimeter to resistance measurement mode (Ohm).
- 📏 Touch the probes to the contacts at room temperature.
- ✅ The device should show "0" or a value close to it (short circuit).
- 🧊 When the sensor is placed in the freezer (cooling), the circuit should break (infinity resistance).
If the circuit is not rings when the handset is warm or, conversely, rings when it is very cold, the thermostat K-59 is faulty and requires replacement. Also, a sign of a malfunction may be sparking of the contacts, which is visually noticeable during operation.
When installing a new thermostat, it is important to position the capillary tube correctly. It should fit snugly against the evaporator in the same place where the old one was attached. Using aluminum tape or a special clamp will ensure proper heat transfer.
⚠️ Attention: The thermostat capillary tube is very thin and fragile. Do not bend it at an acute angle and do not allow impacts. Damage to the tube will lead to the release of gas and complete inoperability of the device.
Frequent errors when setting up your own
Home craftsmen often make common mistakes when trying to set up a refrigerator. The most common of them is an attempt to adjust the temperature when the chamber has not yet cooled down after defrosting. The thermostat will not work correctly until the system reaches a stationary mode.
Another mistake is ignoring the condition of the seals. If the door does not close tightly, no adjustment thermostat will help. The refrigerator will try to cool the entire apartment, working hard.
Also, do not forget about seasonality. In summer, when the room is hot, the refrigerator works harder. Trying to set it to winter standards may result in constant switching on. Take into account external conditions when calibrating.
The influence of condenser dust
If the rear grill of the refrigerator (condenser) is clogged with dust, heat transfer deteriorates. The compressor runs longer and the thermostat may not be able to turn it off in time. Cleaning the grille often solves the problem of “under-turning off.”
FAQ: Frequently asked questions
Is it possible to repair the K-59 thermostat or just replace it?
In most cases, thermostats K-59 are non-separable or can be repaired not economically feasible. Loss of the bellows seal or wear of the contacts requires replacement of the entire assembly. Repair attempts may lead to unstable operation.
Why does the refrigerator turn on immediately after turning off?
This may indicate that the temperature differential is too small or the compressor start relay is faulty. The cause may also be sticking thermostat contacts. Check the integrity of the contacts and, if necessary, replace the regulator.
How do you understand that the calibration has gone wrong and the freon has not run out?
If, when the compressor is running, the evaporator (the back wall inside) cools evenly over the entire area, but the thermostat does not turn off the motor, the problem is in the settings or the thermostat itself. If it is cold only at the beginning of the tube, and then it is warm, there is most likely a freon leak.
Do I need to wait after adjusting the screw?
Yes, definitely. After each change in the position of the adjusting screw, the refrigerator needs from 30 minutes to 2 hours to stabilize the temperature and complete the full operating cycle.