The situation when Indesit refrigerator suddenly stops cool, and only a quiet hum or a single click is heard inside, often taking the owner by surprise. In most cases, the culprit is the starting relay, which stops supplying the necessary impulse to the motor windings. Many technicians advise immediately changing the unit, but sometimes it becomes necessary to check the performance of the compressor itself or start the unit temporarily until a spare part arrives.
Starting the engine compressor bypassing the standard starting system is a procedure that requires extreme caution and understanding of the physical processes occurring inside electrical circuit Direct connection to the network without protective mechanisms can lead to failure of the windings or even fire if the correct sequence of actions is not followed. In this article we will look at a technically competent way to check and temporarily start the motor.
It is worth noting right away that this method is exclusively diagnostic or emergency and is not intended for permanent operation of refrigeration equipment. Long-term operation without standard protection reduces the life of the engine and can be dangerous for the apartment’s electrical network. Below are the technical details for those who have basic electrical skills.
The principle of operation of the trigger mechanism
To understand how to bypass the relay, you must first understand its function. Single-phase asynchronous motors, which are installed in refrigerators Indesit, use two windings: working and starting. The working winding creates the main magnetic field, and the starting winding is needed only at the moment of start, in order to create torque and move the rotor.
Starting relay acts as a circuit breaker that supplies voltage to the starting winding in the first fractions of a second, and then turns it off when the engine reaches rated speed. Older models used devices with a posistor (thermistor), the resistance of which increased sharply when heated, breaking the circuit. In more modern or heavier compressors, electromagnetic relays that respond to current may be used.
If this element fails, the starting winding circuit does not close, and the engine only hums, trying to turn over. Thermal relay, often combined with the starting one in one case, at this moment it is triggered by an overcurrent and breaks the circuit completely to prevent the motor from burning out. This is why the refrigerator clicks cyclically and is silent.
⚠️ Attention: Working with high voltage 220 Volts is deadly. All manipulations to connect the wires should be carried out only with the refrigerator completely disconnected from the network. Do not touch live parts under voltage.
Diagnostics before starting
Before you start creating a temporary circuit, you need to make sure that the problem lies in the relay, and that the relay itself is OK. Primary diagnostics include visual inspection and continuity testing of the windings with a multimeter. If there is a break in the windings or a short circuit to the housing, starting such a unit is pointless and dangerous. compressor OK Primary diagnostics include visual inspection and continuity testing of the windings with a multimeter. If there is a break in the windings or a short circuit to the housing, starting such a unit is pointless and dangerous.
Remove the back cover of the refrigerator and get to the compressor. Disconnect the start relay and thermal fuse. They are usually a plastic box placed over the motor contacts. Carefully remove the insides of the relay to inspect the contacts for carbon deposits or melting.
Using a multimeter in resistance measurement mode, check the integrity of the windings. Locate the three terminals on the compressor: common, start, and run. The resistance between the general and working contacts should be the smallest, between the general and starting - average, and the sum of these two values should be equal to the resistance between the starting and working contacts.
Connection diagram of the compressor windings
For a successful start, you must correctly identify the contacts on the compressor block Indesit. The location of the pins may vary depending on the engine model (for example, series FC or NL), but the marking principle remains the same. Typically, the contacts are arranged in a triangle.
The top contact is most often Common, the bottom left is Run, and the bottom right is Start. However, you cannot rely on geometry alone. Use a tester: the resistance between the common and working contacts is always less than between the common and starting contacts.
The table below shows approximate resistance values for typical compressors installed in Indesit refrigerators. Please note that the values may vary slightly depending on the motor power and year of manufacture.
| Pair of contacts | Winding type | Approximate resistance (Ohm) | Purpose |
|---|---|---|---|
| General - Working | Working (C-R) | 10 - 25 Ohm | Main work |
| General - Starting | Starting (C-S) | 20 - 45 Ohm | Engine start |
| Working - Starting | Total | 30 - 70 Ohm | Check integrity |
| Any - Housing | Breakdown | Infinity | Isolation |
If you find that the resistance between any contact and the copper tube or motor housing is not equal to infinity (there is at least some kind of conductivity), it means that insulation breakdownoccurred. It is strictly prohibited to operate such a compressor, as this will lead to an electric shock when touching the refrigerator body.
Why are the resistances different?
The difference in resistance is due to the thickness and length of the wire. The starting winding is wound with a thinner wire and has more turns to create the necessary phase-shifting torque, so its resistance is higher than that of the working winding, wound with a thicker wire.
Temporary motor starting technology
There are several ways to start the engine without a standard relay. The most common and relatively safe method involves using a button with normally open contacts (for example, a bell button) or manually closing the contacts with an insulated tool for a very short time.
You will need to assemble a circuit where the phase wire of the network will be connected to a common point, and the zero wire will branch into the working and starting windings. A button is installed in the gap in the wire going to the starting winding. Pressing the button simulates the operation of the starting relay, supplying current to the start.
The sequence of actions is as follows:
1. Connect power to the working winding - the motor will hum, but will not start.
2. Briefly (for 1-3 seconds) press the button in the starting winding circuit.
3. The engine should start and gain speed.
4. Release the button. The motor will continue to operate on the working winding.
☑️ Checklist before turning on
It is important not to overpress the button. If you keep the starting winding turned on for more than 3-5 seconds, it may overheat and burn out, since it is not designed for long-term operation. Also make sure that the compressor does not run “idle” for too long without a refrigeration circuit, although this is not critical for a short-term check.
⚠️ Attention: When starting, the compressor consumes a starting current that is significantly higher than the operating current. Make sure that the wires with which you are making a temporary connection have a sufficient cross-section (at least 1.5 mm²), otherwise they may melt.
Using a capacitor for starting
A more professional approach, which is sometimes used by craftsmen, is to use a starting capacitor. Although classic Indesit circuits use inductive starting, adding capacitance can make it easier to start a heavy motor, especially if the network is weakened.
This will require a non-polar capacitor with a voltage of at least 300-400 Volts. The capacity is selected experimentally, usually in the range from 4 to 10 μF for household compressors. The capacitor is connected in series with the starting winding and also requires short-term connection.
This method allows you to create a phase shift that is closer to ideal than with direct starting, which reduces the load on the motor shaft at the time of start. However, for a one-time diagnostic, this is unnecessarily complicated, and the method is more suitable for those who assemble home-made installations based on a compressor from a refrigerator.
Safety measures and risks
Starting the compressor bypassing the relay carries serious risks. The main one is the lack of automatic protection. The standard thermal relay turns off the motor when it overheats or jams. Your circuit does not have this protection, so control of the housing temperature falls on your shoulders.
When the windings overheat, the varnish with which they are impregnated begins to melt and flow out, emitting a specific pungent odor. If you smell a burning smell or see the motor housing getting too hot (over 80-90 degrees), turn off the power immediately. Prolonged overheating leads to an interturn short circuit, after which the compressor can only be disposed of.
In addition, operation without a standard relay means that during voltage surges in the network, the engine will be left without protection. This can lead to an insulation breakdown and failure of not only the refrigerator, but also damage to the wiring in the house.
Below is a table of possible symptoms and their causes in case of incorrect startup:
| Symptom | Probable cause | Action |
|---|---|---|
| Strong vibration | Uneven installation or wear of shock absorbers | Check the legs and suspension |
| Humming without starting | An impulse is not sent to the starting winding | Check the connection diagram |
| Smell of burning insulation | Overheating of the windings or short circuit | Urgently turn off the power |
| Knocks out the machines | Short circuit in the circuit | Check the insulation |
Frequently asked questions and answers
Is it possible to leave the refrigerator running without a relay all the time?
No, this is categorically not recommended. The standard relay provides not only starting, but also overload protection. Constant operation without it will lead to rapid engine wear, overheating and a potential fire. Use this method only for diagnostics or temporary preservation of products until the technician arrives.
Why does the compressor hum, but does not start even with the button?
Perhaps the problem is not in the relay, but in the compressor itself. This may indicate jamming of the piston group (the compressor is “stuck”) or an interturn short circuit in the windings. It is also worth checking whether the voltage is supplied to the contacts at the proper level.
Which wire to use for temporary connection?
Use copper wire with a cross-section of at least 1.5 mm². Aluminum wires or thin “noodles” may not withstand the starting current, which will lead to their heating and melting of the insulation in the very first seconds of operation.
Did the winding burn out if the plugs were knocked out?
Most often, yes. The instantaneous operation of the circuit breaker when turned on indicates a short circuit in the circuit, which in the case of a compressor almost always means a breakdown of the winding insulation. Repairing such a motor is not economically feasible.