Modern household appliances are equipped with complex electronic systems designed to optimize energy consumption and protect expensive components from breakdowns. Among the many abbreviations found in technical documentation or on repair forums, the term PZR often appears, which raises questions among ordinary users. Many people mistakenly believe that this is some kind of exotic freezing function, but in fact we are talking about a critically important safety element.
The decoding of the PZR sounds like Start-Protective Relay, and it is this small component that is responsible for starting the compressor and protecting the engine from overloads. Without a properly functioning EPR, the refrigerator turns into a loud box that makes clicking noises but does not produce cold. Understanding the operating principle of this device will allow you to quickly diagnose the problem and avoid unnecessary expenses on calling a technician for a simple replacement of a part.
In this article we will analyze in detail the device of the start-up relay, consider the reasons for its failure and learn to distinguish between a breakdown of the PZR and a malfunction of the compressor itself. You will learn why induction and positor relays operate differently, and receive practical recommendations for checking the integrity of contacts. This knowledge will become the foundation for independent maintenance of your equipment.
The operating principle and design of a start-up protection relay
A start-up protection relay is an electromechanical or electronic device that controls the supply of voltage to the windings compressor electric motor. At the moment of startup, the refrigerator requires significantly more energy than to maintain operation, and the PZR provides a short-term connection to the starting winding. As soon as the motor rotor reaches the required speed, the relay automatically turns off the starting circuit, leaving only the main winding working.
The second, no less important function is thermal protection. Inside the relay housing there is a bimetallic element that responds to the current passing through the motor. If the compressor seizes or an overcurrent occurs, the bimetallic strip heats up, bends and opens the electrical circuit. This prevents combustion of the motor windings and a fire hazard.
Structurally, the device is divided into two main types, each of which has its own operating features:
- 🔹 Induction (electromagnetic) —they use a coil and a movable core to open the contacts, typical for older models of refrigerators.
- 🔹 Posistor (thermal) —contain a ceramic element (posistor) that changes resistance when heated, which leads to disconnection of the starting winding;s in modern technology.
- 🔹 Combined —combine the functions of a starting relay and a thermal release in a single housing, providing double protection.
⚠️ Attention: Inside the PZR, an asbestos gasket or other materials are often used that can be dangerous if the case is damaged. Never disassemble the sealed parts of the relay unless you have the appropriate skills and protective equipment.
It is important to understand that The service life of the starting relay directly depends on the quality of the voltage in the networkas voltage surges cause the protection to trip and overheat the contacts. Modern PZR models are more resistant to changes, but older induction analogues can stick or, conversely, open the circuit ahead of time. That is why, when replacing, it is important to select an analogue with identical characteristics indicated on the marking.
Typical symptoms of a malfunction PZR
Diagnostics of a refrigerator often begins with an analysis of the sounds it makes. If you hear a distinctive clicking sound, followed by a humming sound from the compressor that lasts a few seconds, followed by a clicking sound and silence, this is a classic sign of a faulty starter. The engine tries to start, the current increases, the thermal protection is triggered and de-energizes the system, after which the cycle is repeated after a certain time interval.
Another obvious symptom is the lack of cold when the fan is running (in No Frost systems) and the condenser walls are hot. In this case, the compressor is either completely silent or running idle, without creating the necessary pressure in the system. In some cases, the compressor housing can heat up to critical temperatures, which indicates the constant passage of current through the operating winding without reaching the operating mode.
Visual inspection can also provide important clues. If you remove the back cover and dismantle the PZR, you will notice the following defects:
- 🔸 Melting of the plastic —indicates overheating of the contacts or poor connection to the compressor terminals.
- 🔸 Burning smell —a clear sign that a short circuit has occurred inside the relay or the insulation has been burnt windings.
- 🔸 Dirt and oxides - moisture or condensation on the contacts leads to conductivity problems and malfunctions.
Sometimes users confuse the breakdown of the PZR with a malfunction of the compressor itself. To differentiate these problems, you can carefully (following safety precautions!) shake the removed relay. If a broken piece of metal or ceramic rattles inside, the device definitely requires replacement. However, even a seemingly intact relay may have a broken calibration of the bimetallic plate, which is invisible to the eye.
Diagnostics and checking the integrity of contacts
To accurately diagnose the state of the start-up relay, you will need a multimeter set to resistance measurement mode (Ohm). Before starting any work, the refrigerator must be completely disconnected from the power supply for at least 15-20 minutes, so that the thermal relay has time to cool down and the residual charge has dissipated. Remove the relay from the compressor pipes, having first memorized or photographed the connection diagram.
Checking the induction relay involves checking the contacts. In the normal position, the resistance between the contacts should be close to zero. If the device shows infinity, then the circuit is broken. To check a posistor element, it is necessary to take into account that at room temperature it has a certain resistance (usually several tens of Ohms), which increases sharply when heated. It is difficult to check the dynamic change in resistance at home, so they often resort to the elimination method or direct replacement.
The checking process is as follows:
- Visually inspect the contacts for carbon deposits or oxidation, if necessary, clean them with fine sandpaper.
- Connect the probes multimeter to the input and output terminals of the relay.
- Shake the device: if the resistance jumps or disappears, it means there is an internal break or poor contact.
- Check the integrity of the bimetallic plate - it should not have cracks or traces of strong thermal effects.
⚠️ Attention: Do not try to repair a burnt out start relay by stripping the contacts or twisting the springs. This is a temporary measure that can lead to failure of the compressor, the cost of which is disproportionately higher than the price of a new relay.
If the multimeter shows a short circuit where there should not be one, or a complete lack of conductivity when closed, the relay is considered faulty. It is also worth checking the wires going from the relay to the compressor - they often fray or melt due to their proximity to hot parts of the engine. Insulation integrity Wires are the key to safe operation.
Is it possible to start a refrigerator without PZR?
Theoretically, you can start the compressor by applying voltage directly to the starting winding through a capacitor, but doing this is strictly prohibited in domestic conditions. This will deprive the engine of protection and can lead to a fire or final breakdown of the unit.
Table of error codes and PZR compliance
In modern electronically controlled refrigerators, a malfunction of the start-up relay is often detected by the main controller. The system diagnoses the compressor not starting or excessive current consumption and displays an error code on the display or indicator panel. Knowing these codes allows you to immediately understand which direction to move in when troubleshooting.
Below is a table of common designations of problems associated with starting the compressor and operating the PZR for various popular brands, which nomenclature may vary depending on the model and year of manufacture.
| Refrigerator brand | Error code | Description problems | Probable cause |
|---|---|---|---|
| LG | Er 07 / Er 17 | Inverter compressor error | Failure of PZR or control board |
| Samsung | 21E / 22E | Compressor operation error | Open circuit of PZR or wedge engine |
| Indesit / Ariston | Alarm flashing | Problem with starting | Starting relay burnt out |
| Beko | Indicator does not light | Compressor does not turn on | Thermal relay malfunction |
| Atlant | Yellow lamp flashing | No cold | Trigger failure |
It is worth noting that electronics can make mistakes. A code indicating a problem with the compressor does not always mean the death of the motor itself. Often the culprit is a cheap part - start relay. Therefore, before agreeing to an expensive compressor replacement, ask for this particular unit to be checked. In 80% of cases, the problem is solved by replacing the relay, which costs a few dollars.
When interpreting codes, it is important to consider the context. If the error appears immediately after plugging in, this may indicate a short circuit in the circuit. If the refrigerator worked for several hours and then generated an error, most likely the thermal protection was triggered due to overload or contamination of the capacitor. Analysis of the time the error occurred helps to narrow down the search area.
The process of replacing the start-up protection relay
Replacing the PZR is one of the simplest procedures in repairing refrigerators, accessible even to a novice if caution is exercised. The main rule is to buy a relay with exactly the same markings or a complete analogue, since the current consumption characteristics of different compressors differ. Installing an unsuitable relay will either make it impossible to start, or cause a lack of protection and burn out of the motor.
Before starting work, make sure that the refrigerator is unplugged from the mains. Remove the rear protective panel at the bottom of the unit to gain access to the compressor. You will see a black cylinder (compressor), to which a plastic or metal box is attached to the side or top - this is our desired relay. It is held on by latches or screws and is placed on three contact pins of the compressor.
Algorithm for replacement:
- 🛠️ Carefully disconnect the wires going to the relay, having previously photographed their location.
- 🛠️ Remove the old relay from the compressor contacts (it may sit tightly, you can wiggle it slightly).
- 🛠️ Install the new relay in place, making sure that it is seated all the way and the contacts match.
- 🛠️ Connect the wires as described earlier photographs and secure the relay housing with latches.
☑️ Check after replacement
After installation, turn on the refrigerator and listen. The launch should be confident, without prolonged buzzing and repeated clicks. The compressor should operate smoothly, with a characteristic low hum. If within 10-15 minutes of operation the relay body does not heat up to a burning state and the refrigerator begins to cool, the repair has been completed successfully. Do not forget to replace the protective cover of the compressor compartment.
Prevention and extension of service life
Although the starting relay is a consumable item, its life can be significantly extended if the refrigerator is provided with the correct operating conditions. The main enemy of the PZR is frequent voltage drops and overheating of the compressor compartment. Stable operation of the electrical network is the key to the longevity of not only the relay, but also the entire electronics of the refrigerator.
Particular attention should be paid to ventilation. The compressor compartment should not be crowded with things, pushed close to the wall or covered with decorative panels without gaps. Overheating causes the thermal protection to operate more often, which leads to degradation of the bimetallic plate and melting of the contacts. Regularly removing dust from the condenser grille (at the back or bottom of the refrigerator) also reduces the load on the motor.
⚠️ Attention: If your region has frequent power surges, be sure to use a stabilizer or surge protector with surge protection function. This will save not only the PZR, but also the expensive inverter compressor.
You should also avoid frequently opening the door and loading hot foods into the refrigerator. This forces the compressor to work non-stop, which increases the time the start relay is active and increases the risk of overheating. Compliance with operating rules is the best prevention of breakdowns.
The influence of room temperature
If the refrigerator is in an unheated room at a temperature below +10°C, the oil in the compressor thickens, and it is much more difficult for the starting relay to start the engine. This can lead to false protection activations.
Frequently asked questions (FAQ)
Is it possible to operate the refrigerator if you remove the faulty PZR and close the contacts directly?
Absolutely not. A direct connection will deprive the compressor of the starting phase (the engine will not start and will hum) and, more importantly, will disable the thermal protection. This is guaranteed to lead to burning of the motor windings and a possible fire.
Why does a new relay burn out a few days after replacement?
There may be several reasons: a relay with unsuitable current characteristics was selected, there are problems with the compressor itself (turn-to-turn short circuit), or critical voltage surges are observed in the network. It is also possible that the contacts were poorly cleaned or loosely tightened.
What is the difference between the PZR for an inverter compressor?
In inverter systems, the classic starting relay is often absent, since the engine is started and controlled by a special electronic unit (inverter). Other protection principles are used there, and replacing a conventional PZR is physically impossible.
How can you tell that it is the compressor that has burned out, and not the relay?
If, when applying voltage directly (which only a master should do), the compressor does not start, hums, or knocks out the circuit breakers in the panel, most likely the problem is in the engine. This is also indicated by the resistance of the windings, measured with a multimeter, if it differs from the nominal value or shows a breakdown on the housing.