A sudden stop of the refrigerator compressor or its characteristic hum followed by a click often indicates a failure of the start-up relay. This small device is responsible for starting the engine and protecting against overloads, being a key element in the electrical circuit. When this part breaks, the refrigerator stops freezing, and food begins to deteriorate, which requires an immediate solution to the problem.
Many equipment owners are faced with a difficulty: the original part may not be on sale, be unreasonably expensive, or the manufacturer has already discontinued production of a particular refrigerator model. In such situations, a logical question arises: how can you replace a failed relay in order to restore the operation of the unit without purchasing an expensive original? The answer lies in the correct selection of a universal analogue that matches the technical characteristics of your compressor.
Independent replacement is possible if you have minimal skills in working with tools and follow electrical safety rules. However, before you go to a spare parts store or order a component online, you need to accurately determine the type of faulty device and its parameters. Start relay - this is not a universal part “for everyone”, and an error in selection will lead to repeated repairs or combustion of the compressor.
Fault diagnosis and symptoms breakdowns
Before looking for a replacement, you need to make sure that the problem lies in the relay, and not in the compressor or thermostat itself. A characteristic symptom is the cyclic turning on of the motor: the unit hums for 3-5 seconds, then a loud click is heard, and there is silence. After some time, the cycle repeats. This indicates that the starting winding does not receive an impulse to start, and the thermal protection is triggered.
Visual inspection often helps to identify obvious defects. If traces of soot, melted plastic, or a burning smell are visible on the relay body, the part definitely requires replacement. It is also worth checking the contacts: oxidation or burnt terminals can prevent the normal flow of current, even if the internal mechanics are intact.
Sometimes a relay looks intact, but does not work. The simplest test is possible for devices with a posistor (PTC). If you shake the part next to your ear and hear rattling, it means the ceramic element inside has crumbled. For more accurate diagnostics, you will need a multimeter, which “rings” the contacts and checks the resistance of the posistor in a cold and warm state.
⚠️ Attention: Before any diagnostics, be sure to disconnect the refrigerator from the power supply. Working with live electrical wiring is deadly, and accidental shorting of contacts can lead to a fire.
Types of starting relays and their features
Understanding the relay design is critical to selecting a replacement. In household refrigerators, there are most often two main types of devices, the operating principles of which are radically different. The first type is electromagnetic relays, which were usually installed on old models of Soviet and early imported refrigerators with high-power compressors.
The second, more modern and common type is posistor (PTC) relays. They are more compact, more reliable and have no moving mechanical parts that could stick. Inside them there is a ceramic element, which, when heated by current, sharply increases its resistance, breaking the starting winding circuit. It is these devices that most often require replacement in modern technology.
Relays can also differ in the method of mounting on the compressor: they can be horizontal, vertical or universal with adapters. The shape of the housing and the arrangement of contacts (2, 3 or 4 pins) also vary depending on the compressor manufacturer, whether Atlant, Danfoss or Secop.
- 🔌 Electromagnetic: have a movable core and coil, often fail due to sticking contacts or weakening of the spring.
- 🔥 Posistor (PTC): have no moving parts, are triggered by changing the temperature of the ceramic element, and are considered more durable.
- ⚙️ Combined: combine a starting relay and a thermal protection relay in one housing, which simplifies installation, but makes the part more expensive.
How to choose an analogue: marking and compatibility
The most reliable way to find a replacement is to focus on the marking of the compressor itself, and not just on the model of the refrigerator. There are numbers and letters stamped on the motor body that indicate its power, coolant and, most importantly, the permissible power range of the starting relay. For example, the marking R600a talks about the type of freon, and the letters L, M, H or Z at the end of the relay code often indicate its power class.
If the original part is not readable or its number is not on sale, you can use cross-number tables (analogues). Many manufacturers, such as Start-Device or Danfoss, produce universal series that are suitable for replacing dozens of original models. The key parameter here is the motor power in watts or the range of operating currents.
When selecting, pay attention to the number of contacts. If you had a relay with three contacts, and you buy one with two, you won’t be able to install it without redoing the wiring, which is not recommended. It is also important to consider orientation: some relays only work in a vertical position, others - in a horizontal position.