Compressor malfunctions and do-it-yourself repairs

A compressor is a technically complex device, the parts and components of which wear out and fail over time. In most cases, only specialists from service centers equipped with modern diagnostic equipment and tools can solve the problem.

Our technicians will not only fix the current problem, but also identify hidden defects. Thanks to the availability of a large assortment of spare parts in specialized workshops, the repair will be completed in a short time. Let's look at the most common causes of failure of an air piston compressor.

Purpose, main elements and principle of operation

The main purpose of air compressor units is to create a continuous, uniform stream of compressed air. The flow of dense gas is subsequently driven by various pneumatic tools.

These can be airbrushes, tire inflation guns, impact wrenches, cutting machines, pneumatic chisels, nailers, etc. In the minimum configuration, the compressor unit is equipped with a supercharger (an engine that creates an air flow) and a receiver (a container for storing compressed gas).

Useful! Compressors with an electric motor of a piston system are most widely used in auto repair shops. In the supercharger crankcase, a transfer rod moves along the axis back and forth, imparting an oscillatory moment to the reciprocating movement of the piston with sealing rings.

The bypass valve system located in the cylinder head works in such a way that when the piston moves downwards, air is taken from the inlet pipe, and upwards - it returns to the outlet.

The gas flow is directed to the receiver, where it is compressed. Due to its design, the supercharger produces an uneven stream of air. Which is not applicable for using a spray gun. A kind of capacitor (receiver) saves the situation, which smoothes out pressure pulsations, producing a uniform flow at the output.

A more complex design of a compressor unit involves attaching additional equipment designed to provide automatic operation, dehumidification and humidification. And if in the case of a simple design it is easy to localize a fault, then the complication of the equipment design makes the search difficult.

The following are the most common malfunctions and methods for eliminating them for the most common compressed gas supply systems with a piston-type supercharger.

Tips for choosing a part

When choosing a check valve for a compressor, you should know the size of the thread cut at the cylinder outlet . The thread may differ in different unit models. The easiest way is to take the faulty part with you and choose a similar one in the store.

If you need to change the return valve, for example, to a more reliable model, you should familiarize yourself with the technical characteristics of the new part. Some of them are not designed to work with high pressure compressors. Usually, the packaging for the return valve indicates the maximum pressure at which it can operate.

The temperature characteristics of this unit should also be taken into account. If the air, after compression, heats up to high temperatures, then you should not buy a plastic unit. Preference should be given to a metal check valve that is installed inside the duct.

Compressor installation defects

To make it easier to find the problem, all defects can be classified according to the nature of the malfunction:

• the compressor unit's supercharger does not start;
• the compressor motor hums, but does not pump air or fills the receiver too slowly;
• upon startup, the thermal protection circuit breaker is triggered or the mains fuse is knocked out;
• when the supercharger is turned off, the pressure in the compressed air container drops;
• The thermal protection circuit breaker is periodically triggered;
• the output air flow contains a large amount of moisture;
• the engine vibrates strongly;
• the compressor operates intermittently;
• the air flow is consumed below normal.

Let's look at all the causes of problems and how to fix them.

System supercharger does not start

If the engine does not start and does not hum, it means that there is no supply voltage supplied to it. First of all, you should use an indicator screwdriver to check the presence of “zero” and “phase”, as well as the reliability of the connection between the plug and the socket. If there is poor contact, measures are taken to ensure a tighter fit. If there is 220 V at the input of the circuit, the fuses of the compressor unit are looked at.

Failed ones are replaced with passive protection devices of the same rating as the defective ones. Under no circumstances are hot-melt inserts designed for higher electric currents allowed. If the fuse blows again, you should find out the cause of the failure - there is probably a short circuit at the input of the circuit.

Information! The second reason why the unit does not start is that the pressure control relay in the receiver is faulty or the level settings are lost.

To check, gas is released from the cylinder and the supercharger is started for a test. If the engine is running, the relay is reconfigured. Otherwise, the faulty part is replaced.

Also, the engine will not start when the thermal overload circuit breaker trips. This device turns off the power supply circuit of the electrical device winding in the event of overheating of the piston system, which can cause the engine to jam.

Useful! Allow the blower to cool for at least 15 minutes. After this time has passed, restart.

How to understand that the device is faulty

The first signal of a malfunction will be non-stop operation of the motor. Working equipment automatically turns off the compressor for 20 minutes, and in case of extreme heat, the modes are adjusted once every 60 minutes.

Interesting to know! Under normal conditions, the average operating cycle of a refrigerator is 12-20 minutes.

When the device breaks down, users note that the refrigerator does not always turn off and is constantly running, and the sound of the compressor becomes very loud. If measures are not taken in a timely manner, the motor may completely fail.

What to pay attention to

The constant functioning of the refrigerator motor does not always have anything to do with problems. The reason for the lack of equipment stopping may be:

• improper operation - location near heat sources;
• violation of installation conditions - there is no gap for ventilation of 10-15 cm, without which the compressor heats up;
• access to sunlight on the back of the device;
• natural wear and tear of the thermostat of outdated models.

Important! Under conditions of non-stop operation, the service life of the compressor will be about 6 months.

The engine hums, but does not work or produces low speeds

When the mains voltage is too low, the electric motor cannot cope with the rotation of the axis, and it will hum. In case of this malfunction, first of all, we check the voltage level in the network using a multimeter (it must be at least 220 V).

If the voltage is normal, then the pressure in the receiver is probably too high and the piston cannot push the air through. In this case, manufacturers recommend setting the automatic “AUTO-OFF” switch to the “OFF” position for 15 seconds, and then moving it to the “AUTO” position.

If this does not help, then the pressure control relay in the receiver is faulty or the bypass (control) valve is clogged.

Expert opinion

Ilya Vyacheslavovich

Consultant for body repair at krasymavto.ru

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You can try to eliminate the last drawback by removing the cylinder head and cleaning the channels. Replace the faulty relay or send it to a specialized center for repair.

Frequency on/off refrigerator too intense

A sign of a breakdown or a circumstance that should alert you is excessively frequent on/off switching, for example, the refrigerator turns on and turns off after a few seconds, makes unsuccessful attempts to start, the cycles are excessively short (every 5 minutes).

Possible reasons for the compressor turning on and off frequently:

• The temperature is set to a minimum, especially in a warm room;
• damage to the seal, distortion of the hinges;
• disruption of refrigerant circulation, and incorrect temperature conditions can be observed in certain parts of the cabinet. The thermostat detects an increase in values ​​and calls the compressor to work, the refrigerator often turns on;
• The thermostat is broken (this is the most common reason). If the door fits tightly and the set and actual temperatures in the refrigerator compartment are the same, then the thermostat probably does not correctly determine its value. If it was the starting relay that was broken, then starting attempts would be observed for 15–30 seconds. also, the device does not turn on at all;
• Compressor defects: insufficient life of a weak, worn-out motor to operate for the required time, the phasing of the cycle is disrupted (the unit cannot move from start-up to operating condition), as well as obvious breakdown when the engine has no stability at all. Often the cause is a short circuit in the winding;
• Freon leak.

The last two breakdowns, when the refrigerator compressor turns on and immediately turns off, are excluded if the unit operates for a long time while the temperature rises.

When the supply voltage is turned off, the air pressure in the receiver drops

A drop in compressed air pressure indicates that there is a leak somewhere in the system. Risk areas include: high pressure air line, piston head check valve or receiver outlet valve. We check the entire pipeline with a soap solution for air leaks. We wrap any detected defects with sealing tape.

The drain valve may leak if it is not tightly closed or faulty. If it is closed all the way, and the soap solution on the spout is bubbling, then we change this part. When screwing in a new one, do not forget to wrap the fum tape around the thread.

If the air line and outlet valve are tight, we conclude that the compressor control valve is not operating correctly. To carry out further work, be sure to bleed all compressed air from the receiver! Next, we continue repairing the compressor with our own hands, disassembling the cylinder head.

Expert opinion

Ilya Vyacheslavovich

Consultant for body repair at krasymavto.ru

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If there is contamination or mechanical damage to the bypass valve, we clean it and try to correct the defects. If the malfunction is not eliminated, then replace the control valve.

Knocking and rattling in the cylinder and piston group

One of the reasons for compressor failure is a faulty piston group. Recognizing a defect in this system is quite simple. They are usually accompanied by knocking, roaring, grinding and other metallic sounds. If the compressor knocks, then its discharge part, where there are many metal parts that interact with each other, is faulty. Due to their friction and wear, extraneous noise and unpleasant sounds appear.

You should not start with such a breakdown; if possible, you should fix it as soon as you hear the first signs of their manifestation. Main malfunctions if the compressor begins to knock and operate louder than before:

• Broken, worn out bearings, connecting rod bushings
• The bearings on the crankshaft have failed.
• Worn piston, rings, piston pin
• Worn cylinder
• Loose cylinder and head bolts
• A solid particle has entered the cylinder
• The cooling impeller has become loose on the pulley

To repair these breakdowns, in simple cases it is enough to tighten all the bolts and nuts. If the piston, cylinder, crankshaft or connecting rod are worn out, then a comprehensive overhaul is required. When repairing a piston group, you may have to bore the cylinder, if it is badly worn and has external defects, and select a repair piston to new sizes. The following are possible defects in the piston system:

• Changing the diameter of the piston, cylinder
• Distortion of the shape of the cylinder mirror shape
• Risks, scratches, burrs on the cylinder walls
• Cracks in the main working part
• Cracks and broken flanges

During long-term operation, due to wear, marks appear on the cylinder surface, and the inner diameter of the sleeve for the eccentric shaft increases. During repairs, cylinders are restored by pressing sleeves into them. Worn bushings for the eccentric shaft are replaced. This repair is quite difficult to do with your own hands without the necessary tools and equipment. Since the most labor-intensive and critical stage is the restoration of the cylinder. Boring is performed on a vertical boring machine using a special device.

This concerns the cylinder; below we will consider the main malfunctions of the compressor crankcase.

• Cracks in the walls of the crankcase cavities
• Deviations in the size and shape of landing pads
• Warping of seats
• Seats for crankshaft bearings are broken

When these units wear out, they must be replaced with new ones. The hole for the bearings is bored on a horizontal boring machine for a larger diameter of the bearings or for pressing in a bushing, followed by boring the pressed bushing to the required diameter. Repair of a compressor of this complexity should be carried out by qualified specialists.

Below, spare parts “repair kit” for major repairs of the compressor and piston group.

Regular activation of automatic thermal protection

This defect is observed when the power supply voltage is too low, poor air flow or elevated room temperature. We measure the voltage in the network using a multimeter; it must be no less than the lower limit of the range recommended . The filter should be replaced or washed according to the unit's maintenance manual.

Interesting! The piston engine is air-cooled and often overheats when placed in a poorly ventilated area. The problem is solved by moving the compressor unit to a room with good ventilation.

Possibility of making it yourself

There is no deep material meaning to independently manufacturing valves; purchasing parts will cost almost more than a ready-made commercially produced valve. Or the workshop at home must have precision drilling, turning and milling machines for independent production of device parts.

Very often, home craftsmen make valves with their own hands to test their own strength in design and assembly. We also produce original valves for domestic innovative beverage production plants or aquarium filtration and aeration systems. Next, the design and production technology of the valves will be considered:

• Ball for water.
• Gravity ball for water.
• Disc-shaped.
• Petal for ventilation.

Figure 3. Reed air valve design

The designs are simple and the technology does not require the use of expensive equipment. It is quite possible to make a simple check valve in a workshop at home. It is enough to have an average level of locksmithing skills.

The gas outlet stream contains a lot of moisture

This situation occurs under the following conditions:

• large accumulation of moisture in the receiver;
• the air intake filter is dirty;
• the humidity in the compressor unit room is increased.

Moisture in the output stream of compressed air is combated using the following methods:

• Regularly drain excess liquid from the cylinder;
• clean or replace the filter element;
• move the compressor unit to a room with drier air or install additional filter-moisture separators.

In general, piston engines are characterized by high vibration. But, if a previously relatively quiet compressor unit begins to rumble, there is a high probability that the engine mounting screws have become loose or the material of the vibration pads has become severely worn out.

Important! This malfunction can be eliminated by pulling all the fasteners in a circle and replacing the polymer vibration isolators.

Compressor runs intermittently

Interruptions in engine operation can be caused by incorrect operation of the pressure control relay or too intense compressed air intake.

Excessive gas consumption occurs due to a mismatch between the compressor performance and power consumption. Therefore, before buying a new pneumatic tool, carefully study its characteristics and air consumption per unit of time.

Expert opinion

Ilya Vyacheslavovich

Consultant for body repair at krasymavto.ru

Ask a Question

Consumers should not take more than 70% of the compressor power. If the power of the supercharger exceeds the demands of pneumatic tools by a margin, then the pressure switch is faulty. We either repair it or replace it with a new one.

Oil enters the working chamber

If oil gets into the working chamber, this is quite a bad sign; of course, this will not lead to complete failure of the compressor, but it may very well cause harm to the painting work and the occurrence of defects during painting. The main reasons for oil getting into places where it is not needed: Low viscosity oil is poured, that is, the oil is too liquid, it seeps through the seals and rings. Oil level is too high. Due to excess oil, it is forcefully squeezed out and enters the chamber. Incorrect oil used. Fill only with special compressor oil.

The pistons and rings in the cylinder block are worn out. Also, wear of the cylinder itself affects the penetration of oil into the working chamber. To eliminate the malfunction, repair of the piston group compressor, which is described above, is required.

Air flow is not normal

This malfunction occurs as a result of a gas leak in the high pressure system or a clogged air intake filter. Air leakage can be eliminated by pulling all butt joints and wrapping them with sealing tape.

Sometimes it happens that when draining condensate from the receiver, they forget to completely close the outlet valve, which also leads to a gas leak. This problem can be easily solved by tightly closing the valve. If the dust filter is clogged, clean it, or better yet, replace it with a new one.

Most of the above malfunctions can be avoided by correctly performing the first start-up and running-in of the mechanisms, as well as by performing regular maintenance.

“Weak points” of famous domestic models

Manufacturers of household appliances constantly assure in advertising that their refrigerators are the most reliable and resistant to malfunctions. However, practice shows that each brand has its own characteristic vulnerabilities:

1. Atlant. A common cause of incorrect freezing mode is a breakdown of the thermostat. Moreover, the malfunction is often easily corrected by returning the tube to its place. Older models do not tolerate summer heat well, so they require moving to the coolest corner.
2. Biryusa. Refrigerators of this brand operate optimally at temperatures from +16˚C to +32˚C. There are often problems with the relay, thermostat, as well as violations of the compressor operating mode.
3. Nord. For these models, the starting relay and thermostat often fail, which can be solved by replacing these devices. It is even more profitable that their warranty period is 5 years.

The Belarusian manufacturer's Atlant brand of refrigerators has gained fame as reliable devices with a service life of a decade or more. Currently, 80% of products are varieties of two-chamber models with one and two compressors. There is no technology that lasts forever; breakdowns also happen in the Atlant refrigerator. Let's determine the main causes of malfunctions.

Timely maintenance guarantees the performance of the unit

In order for the device to function properly over a long period of time, the recommended maintenance should begin during the initial stages of operation. Experts recommend the following actions from the moment of purchase:

1. When opening the transport package, the presence of the installation passport, technical documentation and compliance with the factory inventory of components is checked.
2. Before the first start of the engine, the oil level is checked using the dipstick and, if necessary, topped up to the recommended level. The oil should be filled as recommended by the manufacturer and specified in the technical documentation. To ensure better spreading of the lubricant and check proper operation, let the compressor run for 10 minutes at idle speed.
3. If there are no comments, a pneumatic tool is connected to the compressor unit and work begins. Note: It is not advisable to supply power to the supercharger if there is excess pressure in the receiver.
4. Try to keep track of the operating time of the compressor and change the oil with new oil after 500 hours of operation. To do this, the crankcase flange cover is removed, the waste is drained and the accumulated contaminants are cleaned. Only after this fresh lubricant is poured in.
5. Clean the air inlet filter weekly.
6. After 16 hours of operation, the moisture is drained from the receiver using the outlet valve. Manufacturers also recommend cleaning the inner surface of the cylinder every six months using special products.
7. At the end of the work, the compressor unit is disconnected from the supply network, and the air is bleed from the high pressure system.
8. If the blower has not been used for a long time, the air valve contact pads must be cleaned and lubricated before starting.
9. Non-current-carrying metal parts must be grounded. As a rule, manufacturers lead the grounding conductor into the Euro plug. And you only need to ground the corresponding contact in the socket into which the compressor unit is connected.

Timely compliance with these simple requirements will allow you to keep the mechanism in good condition. Such a labor-intensive procedure as repairing a compressor with your own hands will be required extremely rarely.

Information! Proper grounding will avoid problems with the electrical part of the device. Regular replacement of oil and cleaning filters will prevent premature wear of rubbing parts.

Types of overpressure relief valves

Based on the method of pressing the locking element to the seat, the devices are divided into the following types:

• Spring. The force of elastic deformation of the spring metal keeps the shutter closed. It is selected in such a way that a pressure exceeding a given level pushes the locking element away from the seat. Spring models are available with both constant response pressure and the ability to adjust it. To do this, an adjusting screw is added to the design, which pre-compresses or weakens the spring. During operation, the spring gradually loses its elasticity, and the response value may change.
• Lever cargo. For pressing, the force of gravity is used, acting on a load suspended at the end of the lever. Such a system has wide possibilities for adjusting the response value. To increase it, the load is moved to the end of the lever, to decrease it, closer to the body. In addition to the possibilities for precise adjustment, this design has another advantage: the stability of the release pressure over long periods of time. Lever devices are characterized by large dimensions and weight. They are used as a safety valve for high-capacity compressors installed permanently.
• Electromagnetic. These advanced devices use an electromagnetic solenoid actuator to press the locking element. Such devices operate as an executive element of a centralized automated control system. The pressure sensor can be located next to the valve, or it can be located in a completely different part of the system. Most of them are equipped with an additional working spring. If there is a loss of power or communication with the control system, the relief valve turns into a regular mechanical one.

According to the method of connection, the relief valves are divided into the following types:

• Threaded. The most common type for low pressure relief devices. Easy to install and dismantle even for untrained personnel - a wrench is enough for this. Most often used as an emergency valve for a low-power mobile compressor.
• Flanged. More difficult to install and more expensive, they provide high tightness. used in medium and high pressure systems.
• Welded. Provide maximum tightness and reliability. Difficult to install/dismantle; special equipment and trained personnel are required.

Based on the material from which the device is made, there are:

• Steel. They have high strength and long service life. Withstands great pressure.
• Brass. They are characterized by high corrosion resistance and long service life.
• Plastic. Cheap, but designed for low pressure values.