The sudden cessation of operation of a refrigeration unit or its inability to maintain the set temperature often becomes an unpleasant surprise for the owners. In most cases, if the compressor hums but does not start, or, on the contrary, clicks and immediately goes silent, the problem lies in the start protection relay. This small but critical element is responsible for starting the engine and protecting its windings from overheating. Understanding the principle of its operation and the ability to replace the part yourself can save a significant amount on calling a technician.
Modern household refrigerators, be they classic models Atlant, Indesit or more complex systems LG and Samsung, use similar switching principles. However, the design may vary: there are thermal, posistor and electromagnetic options. Before proceeding with disassembly, it is necessary to accurately diagnose the malfunction, since the symptoms may be similar to problems with the compressor or thermostat itself. Correct diagnosis is the key to successful repair.
In this article we will analyze in detail the algorithm for replacing a faulty element, consider the tools that will be needed in the work, and answer frequently asked questions. Self-repair is possible if you follow safety precautions and strictly follow the instructions. Ignoring simple rules may result in damage to more expensive components or electric shock. Therefore, attentiveness at each stage is your main advantage.
Fault diagnosis: signs of relay failure
You can determine what exactly has failed starting relayby characteristic sound and visual signs. Most often, owners hear a loud click, after which the refrigerator is silent or tries to start again after a certain period of time. The compressor may be hot, which indicates that the engine is trying to overcome inertia without a successful start. In some cases, a characteristic crackling sound is heard, indicating a breakdown or sticking of the contacts inside the device.
Another important symptom is the activation of thermal protection. If the relay does not perform its function of connecting the starting winding, the current in the working winding increases sharply, causing the bimetallic protection plate to heat up. It opens the circuit and the refrigerator turns off. After a while, when the plate cools down, the cycle repeats. This phenomenon is called “cyclic starting”, and it is extremely dangerous for the durability of the motor.
⚠️ Attention: If after clicking and trying to start you smell something burning or see smoke, immediately unplug the device. Operation in this condition may lead to a wiring fire or complete combustion of the compressor.
To be absolutely sure, it is recommended to conduct a visual inspection of the removed part. There should be no traces of melting, black spots or cracks on the body. Inside, if the design allows, the contacts should be clean and free of carbon deposits. Sometimes the fault is hidden inside a posistor, which does not change its resistance when heated, which is difficult to determine visually, but is easy to check with instruments.
Necessary tools and preparation for repair
To successfully replace the refrigerator relay, you do not need complex industrial equipment, but a minimum set of tools must be prepared. First of all, you will need a working one multimeter to check the continuity of the circuit and the resistance of the windings. Without this device, diagnostics will be exclusively guess-work in nature, which is unacceptable in electrical engineering. You will also need a screwdriver (Phillips or flathead, depending on the fastening of your unit) and pliers.
It would be a good idea to prepare a container for small parts so that lost screws do not cause a long search throughout the kitchen. If you plan to clean the contacts or the compressor itself, a soft brush and possibly contact spray will come in handy. The workplace should be well lit, and the space around the refrigerator should be free for access to the back wall.
- 🔧 A set of screwdrivers of various sizes for removing the casing and clamps.
- ⚡ Multimeter for testing contacts and checking resistance.
- 🧤 Dielectric gloves to ensure safety when working with current.
- 🔦 Flashlight for illuminating hard-to-reach places in the engine compartment.
Unplug the cord from the outlet and make sure that the plug is not damaged. If the cord is damaged, it must be replaced first, before working on the relay.
Removing the old start relay
The dismantling process begins with access to the compressor, which is usually located in the lower rear part of the refrigerator. Some models, such as built-in or enclosed refrigerators, may require you to remove the back metal panel. It is usually attached with self-tapping screws around the perimeter. After removing the panel, you will see a black cylindrical or pear-shaped object - this is the compressor to which the required relay is attached. Bosch with the cover closed, it may be necessary to remove the rear metal panel. It is usually attached with self-tapping screws around the perimeter. After removing the panel, you will see a black cylindrical or pear-shaped object - this is the compressor to which the required relay is attached.
The relay is usually placed directly on the terminals of the compressor windings and secured with a metal bracket or plastic clip. Carefully, without excessive force, it is necessary to remove the fixing element. Be careful: plastic parts become brittle over time and may break if handled excessively. If the relay is held on a bracket, it must be bent or moved down, freeing the device body.
After removing the latch, the relay is easily removed from the contact group of the compressor. However, there is no need to rush. Pay attention to the connection diagram: wires are suitable for the relay, which can be fixed with terminals or simply put on the contacts. Before disconnecting the wires, it is recommended to take a photo or sketch a diagram. The color marking of wires is not always standard, and you cannot rely on it alone.
☑️ Preparation for dismantling
Checking the part with a multimeter
Before throwing away the removed part or installing a new one, you should make sure that it is not working and, more importantly, check the serviceability of the compressor itself. To do this, take a multimeter and switch it to resistance measurement mode (Ohm). First, we check the motor windings through the contacts on the relay itself or on the compressor terminals. The resistance between the starting and operating windings, as well as between them and the housing, must comply with technical standards.
Then we check the relay itself. If this is a thermal relay, then in a cold state it should ring (show zero or close to zero resistance). If the resistance is infinitely high, the circuit is open and the relay is faulty. In the case of a posistor starter, the cold resistance is usually 20-50 Ohms. When heated (which is difficult to check at home without a hair dryer), it should increase sharply, opening the circuit.
| Test type | Normal reading | Symptom of malfunction |
|---|---|---|
| Winding resistance | 10-50 Ohm (depending on the model) | Infinity or zero |
| Thermal relay testing | 0 Ohm (closed) | Infinity (break) |
| Thesistor resistance | 20-60 Ohm | Significant deviation from the norm |
| Breakdown to the body | Infinity | Any resistance value |
If the test shows that the relay is working, but the refrigerator does not work, the problem may lie deeper. The compressor may have jammed or the thermostat may have failed. In such a situation, simply replacing the relay will not help, and a more in-depth diagnosis or calling a specialist will be required.
What is a posistor?
A posistor is a semiconductor element whose resistance increases sharply when heated. In starting relays, it is used to automatically turn off the starting winding of the motor after the rotor reaches the required speed.
Installation and connection of a new relay
The purchase of a new spare part should be carried out strictly according to the model of your refrigerator or according to the marking of the old relay. There are practically no universal solutions here, since the current characteristics and geometry of the mounts from different manufacturers (Danfoss, Secop, Embraco) may differ. We begin the installation by connecting the wires to the contacts of the new device, observing the previously made diagram or color marking.
After connecting the wires, carefully put the relay housing on the compressor terminals. It is important that it sits tightly and all the way, ensuring good electrical contact. Looseness or distortion is not allowed, since vibrations during compressor operation can lead to sparking and burning of contacts. If the relay is fixed with a bracket, return it to its place, ensuring reliable fastening.
⚠️ Attention: Never try to secure the relay with electrical tape or glue instead of the standard bracket. The vibration of the compressor is high, and unreliable fixation will lead to broken contacts or a short circuit.
After installing all components in place, do not rush to immediately close the back panel. First, plug in the refrigerator and listen. The start-up should occur with a characteristic hum, turning into a smooth sound of the engine. If you hear clicking noises, an intermittent hum, or the engine hums but does not turn, turn off the power immediately. This is a signal about incorrect assembly or incompatibility of the part.
Starting and testing the system
After a successful first start, it is necessary to check the operation of the refrigerator for 15-20 minutes. During this time, the compressor should gain temperature, and the refrigerator and freezer compartments should begin to feel cold. Pay attention to the operating cycle: the refrigerator should run for a certain time, then turn off and turn on again as needed. Constant operation without stopping may indicate insufficient compressor power or a freon leak.
It is also worth checking the temperature of the compressor housing. It will be warm or even hot - this is normal for a running engine. However, excessive heating, such that the metal cannot be touched, indicates problems. In this case, it is possible that a relay with incorrect current characteristics was selected, and the thermal protection operates too late or does not operate at all.
- 🌡️ Check the uniformity of cooling in the chambers.
- 🔇 Make sure there are no extraneous vibrations or knocks.
- ⏱️ Note the time of the first shutdown cycle (should be at least 5-10 minutes).
If all parameters are normal, you can install the rear protective panel in place. Make sure the wires are not pinched or touching hot parts of the compressor or moving parts (if there is a fan). Tighten all the screws securely so that the panel does not rattle when the unit is operating.
Common mistakes when replacing yourself
One of the most common mistakes is ignoring cleaning the contact group. When installing a new relay, many people forget to check the condition of the terminals on the compressor itself. If they are oxidized or burnt, the new relay will quickly fail or will not provide reliable contact. Cleaning the contacts with fine sandpaper or a file is a mandatory procedure.
Another mistake is using the relay “by eye”. Externally similar parts may have different starting winding resistance or different protection current. Installing an unsuitable relay may result in the engine not starting under load or, conversely, the starting winding not turning off, which will lead to its burning.
⚠️ Attention: Technical characteristics of refrigerators may vary depending on the year of manufacture and the specific modification. Always check the markings on the nameplate of the device and the parameters of the new spare part before installation.
Also, beginners often forget about the waiting time. After unsuccessful startup attempts, the compressor needs time (15-30 minutes) to equalize the pressure in the system and cool down the thermal protection. Attempting repeated launches without a pause is guaranteed to lead to failure. Give the equipment a rest before turning it on again.
Can an old relay be repaired?
In some thermal relays, you can clean the contacts or replace the bimetallic strip, but this is a temporary solution. The reliability of such repairs is low, so replacing with a new unit is preferable.
Questions and answers (FAQ)
How much does it cost to replace a refrigerator relay with a specialist?
The cost consists of the price of the spare part and the work of a specialist. On average, taking into account the on-site visit, repairs will cost 2000-4000 rubles, while independent replacement will only require the cost of the part (300-1000 rubles).
Is it possible to start a refrigerator without a relay?
Theoretically, you can start the engine by applying voltage directly, but this is extremely dangerous and does not have a protection function. Operating without a relay will result in rapid burnout of the compressor windings. It is prohibited to operate a refrigerator without a working relay.
Why does the new relay click, but the refrigerator does not freeze?
This may indicate a malfunction of the compressor itself (interturn short circuit, wedge), lack of refrigerant (freon) or incorrect installation of the relay. The problem may also be in the thermostat, which does not give a command to turn on, although the relay clicks when power is applied.
How do you know which relay to buy?
You need to remove the old relay and look at its markings. You need to look for an analogue by model number (for example, PTCR, R6, etc.) or by parameters: compressor power (in Watts or HP), type of refrigerant and contact location (vertical/horizontal).
Is it dangerous to change the relay yourself?
If you follow electrical safety rules (disconnecting from the network), there is a risk minimal. The main danger is electric shock when the device is turned on or damage to the compressor due to careless installation. If you are not confident in your abilities, it is better to turn to professionals.