A sudden stop of the compressor or a characteristic click, followed by a hum and subsequent silence of the unit, often indicates a failure of the starter mechanism. It is Starting relay P1 responsible for starting the engine and protecting it from overloads, being one of the most vulnerable components in the design of household refrigerators. Understanding the principle of its operation and the skills of correct replacement will allow you to independently return the equipment to life without calling a specialist.
Models of the series P1, P1-01, P1-03 and their modifications have been installed on Soviet and Russian refrigerators for decades, such as Atlant, Biryusa, Saratov and Orsk. Despite the apparent simplicity of the design, the installation process requires care, since incorrect connection can lead to burnout of the compressor windings. In this material we will analyze all the nuances of diagnostics, selection of analogues and safe installation of the device.
Before starting physical actions, you need to make sure you have basic tools and comply with electrical safety rules. Working with high voltage electrical appliances requires responsibility. If you are not confident in your abilities, it is better to turn to professionals, but for most home craftsmen this task is quite possible if you follow the instructions.
Principle of operation and design of relay P1
The starting relay is an electromagnetic switch that controls the supply of voltage to the starting winding of the compressor motor. When the refrigerator is turned on, the motor rotor is stationary, and to create the initial torque, an additional winding must be connected. Relay P1 automatically closes the circuit of the starting winding, and after a set of revolutions (after about 1-3 seconds) opens it, leaving only the main winding to work.
Inside the device body there is a movable core and contacts. When current passes through the coil, a magnetic field is created, drawing in the core and closing the contacts. In parallel with the starting function, thermal protection often operates, which opens the circuit when the current or temperature of the compressor housing critically increases. This prevents the insulation from melting and failure of the expensive unit.
⚠️ Attention: The relay housing can become very hot during operation. Do not touch the parts immediately after trying to start the compressor to avoid burns.
The design of the relay RTK (analogue to P1) or P1 implies a specific orientation during installation. Inside there is a movable rod with contacts, which must move freely under the influence of gravity and a magnetic field. That is why most of these relays are marked “TOP” or an arrow indicating the direction of installation. Incorrect orientation of the relay (for example, installation upside down) will lead to the fact that the contacts will not open after starting, which will cause the starter to burn out windings.
Diagnostics of faults before replacement
Before buying a new part, you need to make sure that the problem lies in the relay, and not in the compressor or wiring itself. Symptoms may be similar, so an initial check is required. Often, equipment owners immediately blame the relay, while the problem may be a broken wire or a jammed motor.
For diagnostics, you will need a multimeter. First, visually inspect the device: if the inside is blackened, the plastic has melted or there is a burning smell, replacement is inevitable. If there is no external damage, you need to “ring” the contacts. In normal condition, the resistance between certain contacts should be close to zero, and in other cases it should be absent.
There is a simple method for checking the functionality of the relay without instruments, but it requires caution. If you hear a click when you turn on your refrigerator, the hum lasts a few seconds, then another click and silence - this is a classic sign of a faulty starter or a jammed compressor. Try to gently shake the relay: if you hear a knock inside, it means the mechanism is damaged and requires replacement.
- 🔌 No reaction: The compressor is silent, there is no light in the chamber - the problem is in the network or thermostat.
- 🔊 Humming and clicking: The motor hums for 5-10 seconds and turns off - most likely the relay has burned out or the compressor has jammed.
- 🔥 Case heating: The compressor is hot, but does not start - the thermal protection inside the relay may be faulty.
Selection of analogue and compatibility models
Relay P1 has many modifications and complete analogues, which are interchangeable in most cases. On the market you can find devices labeled RTK-1X, RTK-1-3, 33.0004.000 and others. The main thing when choosing is compliance with the rated current of the compressor and the type of refrigeration unit.
It is important to pay attention to the operation current, which is usually indicated on the housing. For medium-sized household refrigerators, this parameter is most often in the range of 1.3–1.6 Amperes. Installing a relay with too high a response current will not protect the motor, and one with too low will lead to constant false shutdowns.
| Relay model | Analogs | Rated current (A) | Compatibility |
|---|---|---|---|
| P1-01 | RTK-1, 33.0004.000 | 1.3 | Atlant, Biryusa |
| P1-03 | RTK-1-3, 100210 | 1.6 | Saratov, Orsk |
| P1-12 | RTK-1-2, 33.0004.001 | 1.8 | Freezers |
| RTK-X | P1, DANFOSS 101N0110 | 1.4 | Universal |
When purchasing, pay attention to the number of contacts and their location. Some modern analogues may have an additional contact for connecting a capacitor or indication, which was not used in older circuits. In this case, the extra contacts simply remain free if they are not involved in the electrical circuit of your refrigerator.
Step-by-step instructions for replacing the relay
The replacement process requires care and adherence to the sequence of actions. First, you need to completely turn off the power to the refrigerator by removing the plug from the socket. This is a critical step, as working with live parts can be deadly. Then move the unit away from the wall to gain access to the rear wall.
Remove the rear protective cover at the bottom of the refrigerator where the compressor is located. You will see a black cylindrical or pear-shaped motor with a plastic box attached to the bottom or side of it - this is our relay. It can be attached to a bracket or simply put on the contacts.
☑️ Checklist before starting work
Carefully remove the old relay. It may be a tight fit, so wiggle it slightly from side to side, but don't yank too hard to avoid breaking the wires. Remember or take a photo of which wire is connected where. Usually the terminals are marked: S (Start) - starting winding, R (Run) - working winding, C (Common) - common wire.
⚠️ Attention: Wires may be oxidized or brittle. Be careful not to damage the insulation and contact pads on the compressor.
Install the new relay P1 in place of the old one, observing the orientation (the “TOP” arrow should face up). Push the wires onto the appropriate terminals until you hear a characteristic click. Make sure the connection is tight and the wires are not loose. Return the protective casing and metal bracket, if any, to their place.
Connection diagram and contact marking
Correct connection of contacts is the key to successful engine starting. In relay type P1 i RTK the diagram is usually standard, but a visual check never hurts. The connection diagram is often marked on the device body, but it may be erased or unreadable.
Let's consider a typical pinout. Terminal C (Common) is connected to the common point of the compressor windings. From it, current flows to the relay coil. The terminal R goes to the working winding, and S to the starting winding. Inside the relay, the contacts C and S close at the moment of start.
What to do if the colors of the wires do not match the diagram?
In old refrigerators, the colors of the wires could have faded or been replaced during a previous repair. The most reliable way is to test the compressor windings with a multimeter. The resistance between C and R will be less than between C and S, and between R and S it will be total.
If your model uses a capacitor, it is connected in parallel with the starting winding or in an open circuit of the starting winding, depending on the specific modification of the circuit. In classic Soviet refrigerators, the capacitor was often absent, and only the inductive starting phase was used.
- 🔍 Checking the contacts: Make sure that the males on the compressor are not oxidized and have good contact with the females of the relay.
- 🧊 Orientation: The relay should hang strictly vertically, the rod inside should move freely downwards under its own weight.
- 🔧 Fixation: Use the original clamping bar so that the relay does not vibrate during compressor operation.
Frequent errors during installation and startup
One of the most common mistakes is ignoring the state of the compressor itself. If a relay burns out, this is often a consequence, not a cause. For example, when the piston group jams, the current in the windings increases, the thermal protection of the relay is triggered, but over time the contacts may become welded or burnt. Installing a new relay on a jammed motor will cause it to burn out instantly.
The error of incorrect selection of the current characteristic is also common. Installing a relay marked 1.8A instead 1.3A can lead to the fact that the protection will not work during an overload, and the motor windings will begin to heat up above the permissible norm. This reduces the life of the compressor by several times.
Do not forget about the cleanliness of the contacts. If you are replacing a relay on an old refrigerator, clean the contacts on the compressor itself with fine sandpaper or a file. Oxides create additional resistance, causing heating and unstable operation.
Checking operation after installation
After replacing the relay P1 it is necessary to conduct a test run. Plug in the refrigerator. You should hear a clear click of switching on and a smooth hum of the motor. After a few seconds (when the relay opens the starting circuit), the nature of the sound may change slightly, becoming more uniform.
Pay attention to the temperature of the relay body. After 10-15 minutes of operation, it may be warm, but not hot. If the relay becomes hot, smokes or makes a crackling noise, turn off the device immediately. This indicates a malfunction in the circuit or incorrect installation.
It is important to let the refrigerator operate for at least an hour without loading food to ensure the stability of the on and off cycles. If the motor runs jerkily or often turns off due to thermal protection, a more in-depth diagnosis of the refrigerant system or the compressor itself will be required.
Is it possible to install a relay with a different current rating?
For a short time, the refrigerator may start. However, operation with an unsuitable tripping current is dangerous. If the current is too high, the overload protection will not operate. If it is too small, the relay will knock out every time it starts.
Why did the new relay burn out immediately after installation?
Most likely, the problem is not in the relay, but in the compressor (interturn short circuit, jamming) or in a power surge in the network. It is also possible that the relay was installed upside down.
Where can I find the current marking on relay P1?
Usually the rated current (for example, 1.3, 1.6, 1.8) is stamped on the side of the plastic case or on the metal cover. Look for numbers next to the letter “A” or just a numerical value.
Do relay contacts need to be lubricated?
No, lubricating the contacts with electrically conductive or conventional lubricants is strictly prohibited. This will lead to carbon deposits and sticking of contacts. The device operates “dry.”