How to adjust the relay in the refrigerator: step-by-step guide

A modern refrigerator is a complex unit, where each element is responsible for maintaining optimal storage conditions for food. One of the key components that ensure stable operation of the cooling system is relay. It is this unit that controls the start and stop of the compressor, responding to changes in temperature inside the chambers or refrigerant pressure in the system.

Many owners of household appliances are faced with a situation when the device stops freezing or, conversely, starts working without interruption, turning food into ice blocks. Often the root of the problem lies in the improper operation of the starter mechanism or thermostat. Understanding the operating principle of these parts allows you to carry out diagnostics and perform the adjustment yourself, without resorting to the expensive services of service centers.

In this article we will analyze in detail the design of various types of relays, consider the tools necessary for the work, and give step-by-step instructions for setting them up. You will learn how to distinguish a mechanical breakdown from a settings failure and when specialist intervention is really necessary. Attention: working with electrical circuits requires compliance with safety measures.

Types of relays in refrigeration equipment and their purpose

Before you start making adjustments, you need to clearly understand what type of device you are dealing with you're dealing. In household refrigerators, there are most often two main types of relays: start-up protection and temperature (thermostat). The start-up protection relay is responsible for supplying voltage to the compressor motor windings at the time of startup and turns it off in case of overload. Thermoregulator it also monitors the temperature in the evaporator or chamber and opens the compressor power circuit when the specified values are reached.

Temperature relays can be mechanical, where the sensitive element is a bellows tube with gas, or electronic, controlled by thermistors. Mechanical models, such as TAM-112 or K-59have screws to adjust the response range. Electronic analogues most often cannot be repaired and require complete replacement or reprogramming through the service menu.

Start-protection mechanisms are divided into induction and posistor. Induction ones use an electromagnetic coil to close the contacts, and posistor ones use a special ceramic element that changes resistance when heated. Predominantly mechanical thermostats are subject to adjustment, since starting relays are usually sealed and do not have external adjustment screws.

Incorrect identification of the relay type can lead to an attempt to adjust what is being adjusted is not subject to, which may result in equipment failure. It is important to visually inspect the device: the presence of threaded holes with seals or screws for a screwdriver usually indicates the possibility of adjustment.

Tools and preparation for working with relays

High-quality adjustment is impossible without the appropriate tools. To work, you will need a set of screwdrivers (Phillips and flathead), a multimeter to check the integrity of contacts and voltage, and pliers with insulated handles. If you plan to work with a thermostat, you may need thermometer to control the temperature inside the chamber.

Before starting any manipulations, you must completely turn off the power to the refrigerator. Unplug the power cord from the outlet. This is a critical step as even briefly touching live parts can cause serious injury. Remove the rear protective panel or decorative cover inside the refrigerator compartment to gain access to the relay.

⚠️ Attention: Before removing the relay, be sure to photograph or sketch the wiring diagram. Mixed-up contacts can lead to a short circuit or combustion of the compressor.

For accurate diagnosis and subsequent adjustments, it is also useful to have an alcohol-containing contact cleaning fluid and rags on hand. Dust and oxides on the contacts can distort the readings or prevent the normal closure of the circuit, which is often mistaken for a malfunction of the mechanism itself.

Diagnostics of faults in the pressure switch and thermostat

Before turning the adjusting screws, you should make sure that the problem is in the settings, and not in a physical breakdown. Characteristic signs of a malfunctioning thermostat are the continuous operation of the compressor or its complete refusal to turn on. If the motor hums, but does not start, or immediately knocks out the circuit breaker, the problem may be in the start relay.

To check the thermostat, you can use the “freezing” method. Remove the thermostat, place its sensitive tube in a container with water and ice, and test the contacts with a multimeter. When cooling, the contacts should open. If this does not happen, the mechanism requires replacement or serious reconfiguration. The starting relay is checked visually for the presence of carbon deposits and continuity of the windings.

A common mistake is trying to adjust the relay when the problem lies in a freon leak. If there is not enough refrigerant in the system, the pressure will not reach the relay threshold and the compressor will not start. In such cases, adjusting the screws will not have a long-term effect.

Step-by-step instructions: how to adjust the thermostat

Adjustment of the mechanical thermostat is carried out by rotating special screws located on the device body. Usually there are two of them: one is responsible for the response temperature range (on/off), and the second is responsible for the differential temperature (the difference between on and off). There are often seals on the screws that will have to be broken.

First, find the adjusting screw responsible for the switching temperature. Rotating it clockwise usually increases the temperature at which the compressor turns off (makes the refrigerator “warmer”), and counterclockwise it lowers it (makes it “colder”). Make turns no more than half a turn, after which give the system 20-30 minutes to stabilize.

The second screw regulates the temperature difference. Increasing the differential results in rarer but longer compressor cycles. Decrease causes the unit to turn on more often, but work for less time. The optimal difference is 2-3 degrees Celsius.

During the setup process, use an external thermometer placed in the center of the refrigerator compartment. Do not rely solely on feel or built-in indicators, which may have inaccuracies. Record the moments when the compressor turns on and off to understand the current operating range.

⚠️ Attention: Do not unscrew the adjusting screws all the way unless necessary. This can lead to depressurization of the bellows or breakage of the threaded mechanism, after which the relay will have to be thrown away.

Setting the compressor start-protection relay

Unlike thermostats, start-protection relays (PPR) rarely have external adjustment elements. However, in some older models or specialized industrial relays, it is possible to adjust the cut-off current or operating time. If your relay is of type RTK or RTP, it, as a rule, is not regulated, but only replaced.

If you are dealing with an adjustable thermal relay protection, adjustment is made by changing the tension of the bimetallic strip. This is done carefully by bending the plate or rotating the calibration screw, if provided by the design. The purpose of the setting is to achieve circuit opening at a current exceeding the rated motor current by 10-15%.

It is important to understand that incorrectly setting the protection can lead to the relay turning off a healthy motor during starting currents (false operation) or, worse, not turning it off when overloaded, which will lead to burnout of the windings. For precise adjustment, an ammeter is required, connected to the power supply circuit.

Table of typical parameters and faults

For ease of diagnosis and configuration below There is a table with the main parameters that you should pay attention to when working with various types of relays. This data will help determine whether your unit is within the normal range.

Analysis of data from the table allows you to quickly compare the behavior of your refrigerator with reference values. If the parameters deviate greatly from the norm even after adjustment, this is a signal of a deep technical problem.

Common mistakes when adjusting yourself

One ​​of the most common mistakes is ignoring the condition of the door seals when setting the thermostat. If the door does not close tightly, heat enters the chamber, and even a properly configured relay will cause the compressor to run continuously. Always check the tightness of the circuit before tampering with the electronics.

Another mistake is rough mechanical impact. An attempt to remove a soured screw by force often leads to breakage of the plastic relay housing or stripping of the threads. Use a penetrating lubricant (such as WD-40) if the screw does not budge, and proceed carefully.

Also, users often forget about the system's response time. After adjusting the screw, the temperature inside the chamber does not change instantly, but during the cooling cycle. Waiting for results in 5 minutes is pointless; the minimum interval for assessing changes is 30-40 minutes.

⚠️ Attention: Technical characteristics and relay designs may vary depending on the manufacturer and year of manufacture of the refrigerator. Always check the official documentation for your specific model, as the location of the screws and the direction of rotation may be opposite.

Questions and answers on relay adjustment