The situation when the refrigerator suddenly stops cooling, and water has already begun to flow inside, is familiar to many. At such moments, the first thing you want to do is check whether you are alive compressoror whether the problem lies in the control module. Starting the motor, bypassing the standard electronics, is a standard diagnostic procedure that allows you to save time and money on calling a technician.
However, despite its apparent simplicity, working with high voltage requires strict adherence to safety precautions. In this article we will look at how to safely start the compressor directly, what tools will be required and what to pay attention to when analyzing the test results.
It is important to understand that this method is intended exclusively for short-term diagnostics of the health of the electric motor. Long-term operation in this mode it is strictly prohibited, since the lack of standard protection can lead to overheating and fire.
Operation principle and design of the starting relay
Before grabbing the wires, you need to clearly understand how a standard single-phase motor refrigerator works. Unlike three-phase analogues, it cannot start on its own and requires an additional device - a starting relay. It is this that briefly supplies current to the starting winding, creating the necessary torque.
Modern compressors are most often equipped with positor relay, which is a ceramic element that changes its resistance when heated. When voltage is applied, the posistor is cold and passes current, but quickly heats up and opens the starting winding circuit. If this element is faulty, the motor will only hum, but will not start.
There are also old-style electromagnetic relays, where the contacts are opened by changing the current in the winding. Understanding your relay type is critical, as the forced start pattern will vary depending on the design.
⚠️ Attention: Never leave a compressor running bypassing the relay on for more than 10-15 seconds. Without thermal protection, the windings can burn out in a matter of seconds, turning the repair into the purchase of a new unit.
For successful diagnosis, you will need a multimeter, a screwdriver, pliers and, possibly, a new starter for testing. If you are not confident in your abilities, it is better to stop at this stage and call a specialist.
Necessary tools and safety measures
Working with electric current of 220 volts poses a direct threat to life. The first and most important tool is your caution. Before starting any work, the refrigerator must be completely disconnected from the electrical network and the plug removed from the socket.
You will need the following tools to carry out high-quality diagnostics:
- 🔧 Multimeter — to check the integrity of the windings and the presence of voltage.
- 🪛 A set of screwdrivers — for dismantling compressor casing and terminal removal.
- 🧤 Dielectric gloves - a mandatory element for protecting hands when applying power.
- 🔌 Cord with plug - for applying voltage directly to the contacts.
Make sure the work area is well lit and the floor is dry. There should not be any metal objects (rings, watches, bracelets) on your hands. It is also worth preparing a fire extinguisher just in case, although if you follow the rules you will not need it.
If you see melted wires, blackened plastic or smell burnt insulation, further attempts to start are strictly prohibited. These are signs of an interturn short circuit or a burnt out winding, which requires replacing the compressor.
Connection diagram: step-by-step instructions
The starting process begins with gaining access to the electrical part of the motor. Remove the rear protective cover of the refrigerator, locate the black cylindrical compressor tank and the plastic casing covering the terminal block. Carefully remove the cover by unfastening the latches or removing the screw.
You will see three or four pins on the terminal block. They are usually arranged in a triangle. Two of them are the terminals of the working and starting windings, and the third (often located separately or marked with ground) is ground. To start, we need to apply phase and zero to the corresponding contacts.
☑️ Check before starting
The connection diagram is simple: one wire from the power cord (phase) is connected to the contact of the working winding, and the second wire (zero) is connected to the contact of the starting winding. However, in order for the motor to start and work, you need to correctly simulate the operation of the relay.
Here's how to do it correctly:
- ⚡ Preparation: strip the ends of the power cord wires.
- 🔌 Connection: press the wires to the corresponding contacts on the compressor block (use Do not hold electrical tape or clamps with your hands!).
- 🚀 Start: Plug the plug into the socket. If the motor does not hum, lightly shake the wires or try swapping the contacts of the starting and working windings.
- 🛑 Stop: immediately unplug the plug from the socket after checking the operation (3-5 seconds).
⚠️ Attention: In some refrigerator models (for example, Indesit or Stinol), the wiring diagram may differ. Always check the technical documentation or markings on the relay body before applying voltage.
Diagnostics of faults by sound and behavior
After a short switching on, carefully analyze the behavior of the compressor. The sound and pattern of shaft rotation can tell a lot about the internal state of the unit. A hum without starting often indicates a jammed piston group or a malfunction of the starting winding.
If the engine starts, but runs with a strong metallic clanging or knocking noise, this is a sign of worn bearings or damaged valves. In this case, operation is impossible and replacement is required. Quiet and smooth operation indicates that the mechanical and electrical parts of the motor are in good working order.
What to do if the machine knocks out?
If, when you try to start, the plugs instantly knock out or the RCD is triggered, this is a sure sign of a short circuit inside the windings or a breakdown on the housing. Further switching on is useless and dangerous.
Also pay attention to the temperature of the case. If within 5-10 seconds of operation the metal around the terminals or the cylinder itself begins to heat up rapidly, this is a bad sign. A normal compressor heats up gradually over 15-20 minutes of operation.
A frequent problem is the breakage of the internal thermal protection. If the multimeter shows infinite resistance between the contacts, the thermal protection may have tripped. In this case, the compressor must be allowed to cool for an hour and try again.
Table of typical faults
For ease of diagnosis, we have collected the main symptoms and their possible causes in a single table. This will help you quickly navigate the situation and make the right decision on repairs.
| Symptom | Probable cause | Action |
|---|---|---|
| The engine hums, but does not start | The starting relay is faulty or jammed | Replace the relay, check the free play of the shaft |
| Silence, no reaction | Breakage of the winding or thermal protection | Ring the windings multimeter |
| Strong knocking and vibration | Broken bearings or valves | Replacing the compressor |
| Knocks out the machine in the panel | Short circuit in windings | Urgent replacement of the compressor |
Using this table allows you to weed out simple problems that can be solved by replacing the relay from complex cases that require expensive repairs. Remember that diagnosis is only the first stage.
Checking the resistance of the windings with a multimeter
The most reliable way to confirm or refute an electrical fault is to measure the resistance. To do this, switch the multimeter to the resistance measurement mode (Ohms) and check the pairs of contacts on the compressor block one by one.
Normal readings for a working engine vary depending on the power, but usually range from 10 to 30 Ohms for the working winding and a little more for the starting winding. The resistance between any contact and the copper tube (housing) must be infinite.
If you see values close to zero, this is a short circuit. If the device shows one (infinity) between the contacts of the windings, it means you have a break. In both cases the compressor must be replaced.
It is also important to check the integrity of the power cable and plug. Often the problem lies in the frayed wire, and not in the refrigerator itself. Ring the cord from the plug to the entrance to the compressor.
Common mistakes during self-repair
Beginners often make mistakes that can lead to additional costs. One of the most common is an attempt to start a three-phase compressor from a single-phase network without capacitors. This is impossible without special equipment and will only lead to humming.
Another mistake is ignoring the condition of the refrigerant. If there is no freon in the system (leakage), running the compressor “dry” even for a few seconds can be dangerous, although modern models have protection. But the main thing is that you will not check the quality of cooling without gas.
⚠️ Attention: Never cut through the copper tubes of the cooling system if there is still pressure in them. The refrigerant can escape under pressure and damage your eyes or skin.
Also, you should not use twisted wires without soldering or high-quality terminals to connect. Poor contact will result in sparking, heating and possible fire. All connections must be reliable.
FAQ: Frequently asked questions
Is it possible to leave the refrigerator running directly compressor?
No, absolutely not. Direct connection is only used for diagnostic purposes for a few seconds. Without a start relay and thermal protection, the compressor will burn out or cause a fire.
Where can I find a wiring diagram for my refrigerator model?
The diagram is often applied to the start relay housing itself or pasted on the inner wall of the compressor niche. You can also find documentation for the model Atlant, Bosch or another brand on the Internet.
Why is the compressor hot, but does not start?
This may be a sign of jamming of the piston group ("wedge") or internal thermal protection tripping due to overheating. Let it cool down and try to start it with a new relay.
How much does it cost to replace a compressor?
The cost consists of the price of a new unit (from 3,000 to 10,000+ rubles) and the cost of replacement work, including evacuation and refilling with freon. It is better to check the exact price at service centers.