DIY screw compressor repair

There are situations when the air compressor, peacefully rattling the engine in the corner of the garage, starts to malfunction, or even turns off altogether. And at this moment, as luck would have it, there is a need for it. Do not be afraid, after studying theoretical information, repairing a compressor with your own hands will not seem like something unattainable.

The main purpose of air compressor units is to create a continuous, uniform jet of compressed air. The dense gas stream is then driven by various pneumatic tools. These can be airbrushes, tire inflation guns, wrenches, cutting machines, pneumatic chisels, nailers, and more. 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).

Compressors with a piston system electric motor have found the greatest application in car repair shops. In the supercharger crankcase, the transfer rod moves along the axis back and forth, giving the oscillatory moment to the reciprocating movement of the piston with O-rings. The bypass valve system located in the cylinder head works in such a way that when the piston moves downward, air is taken from the inlet pipe, and upward - it is returned to the outlet.

The gas flow is directed to the receiver, where it is compacted. Due to its design, the blower produces an uneven air stream. Which is not applicable to spray gun use. A kind of condenser (receiver) saves the situation, which smooths out the pressure pulsations, giving out a uniform flow at the outlet.

A more complex design of the compressor unit implies the attachment of additional equipment designed to provide automatic operation, dehumidification and humidification. And if in the case of a simple execution it is easy to localize a malfunction, then the complication of the equipment execution complicates the search. The following are the most common faults and remedies for the most common piston-type compressed gas systems.

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

• Compressor unit blower does not start
• Compressor motor hums but does not pump air or fills air reservoir too slowly
• At start-up, the thermal protection circuit breaker is triggered or the mains fuse is blown out.
• When the blower is turned off, the pressure in the compressed air tank drops
• The thermal protection circuit breaker is periodically triggered
• Exhaust air contains a lot of moisture
• Engine vibrates violently
• Compressor runs intermittently
• Air flow is consumed below normal

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

If the engine does not start and does not hum, then the supply voltage is not applied to it. First of all, using an indicator screwdriver, check the presence of "zero" and "phase", as well as the reliability of the plug-to-socket connection. In case of poor contact, measures are taken for a tighter fit. If there is 220 V at the input of the circuit, the fuses of the compressor unit look.

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

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 out of order. To check, gas is released from the cylinder and the supercharger is tested. If the engine is running, the relay is reset. Otherwise, the defective part is replaced.

Also, the engine will not start when the thermal overload circuit breaker is triggered. This device turns off the power supply circuit of the winding of the electrical device in case of overheating of the piston system, fraught with seizure of the motor. Let the blower cool down for at least 15 minutes. After this time has elapsed, restart it.

With an underestimated mains voltage, the electric motor does not master the scrolling of the axis, while it will hum. With 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 does not overpower the pushing of air. In this case, manufacturers recommend setting the “AUTO-OFF” automatic 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 switch in the receiver is faulty or the bypass (check) valve is clogged.

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

Compressor start-up is accompanied by blown fuse or activation of automatic thermal protection

This malfunction occurs if the installed fuse is below the recommended rated power or the supply network is overloaded. In the first case, we check the compliance of the permissible currents, in the second, we disconnect part of the consumers from the electric main.

A more serious cause of the malfunction is incorrect operation of the voltage relay or breakdown of the bypass valve. We bypass the relay contacts according to the scheme, if the engine is running, then the actuator is faulty. In this case, it is more advisable to contact an official service center for technical support or replace the relay yourself.

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

The drain cock may leak if not properly closed or defective. If it is closed all the way, and the soapy solution is bubbling on the spout, then we change this part. When screwing in a new one, do not forget to wind up the fum tape on the thread.

In the case of tightness of the air line and the exhaust valve, we conclude that the compressor control valve is not working correctly. For further work, be sure to bleed all the compressed air from the receiver! Next, we continue to repair the compressor with our own hands, disassembling the cylinder head.

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

This defect occurs when the power supply voltage is too low, the air flow is poor, or the room temperature is too high. We measure the voltage in the network using a multimeter; it must be at least the lower limit of the range recommended by the manufacturer.

Poor air flow into the discharge system is due to a clogged inlet filter. The filter should be replaced or washed according to the unit's maintenance manual. The piston engine is air-cooled and often overheats when in a poorly ventilated area.The problem is solved by moving the compressor unit to a room with good ventilation.

This situation occurs under the following conditions:

• Large accumulation of moisture in the receiver
• Air intake filter dirty
• The humidity in the room of the compressor unit is increased

Moisture in the output stream of compressed air is fought by the following methods:

• Drain excess fluid from the cylinder regularly
• 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 prone to high vibration. But, if the previously relatively quiet compressor unit begins to rumble, there is a high probability that the engine mounting screws are loosened or the material of the vibration cushions is worn out. This malfunction is eliminated by pulling all fasteners in a circle and replacing the polymer vibration isolators.

Interruptions in the operation of the engine can be caused by incorrect operation of the pressure control switch or too intensive extraction of compressed air.

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

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

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 minimized 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 drain valve, which also leads to a gas leak. This problem is easy to solve - by tightly closing the valve. If the dust filter is clogged, clean it or, even better, replace it with a new one.

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

In order for the device to function properly for a long time, the recommended maintenance should be started at the initial stages of operation. Experts recommend the following actions from the date of purchase:

Timely observance of these simple requirements will keep the mechanism in good condition. Such a time-consuming procedure as repairing a compressor with your own hands will be required extremely rarely. 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.

Forum on compressors, compressor equipment, equipment and technologies

lampolom 13 Sep 2013, 15:27

Dear specialists!
I ask you to help a novice “destroyer” with the issue of replacing bearings on screw blocks.
if there is a visual aid I will be 1000 times grateful.

I ask you to share your experience.
how realistic is the replacement of bearings and how long does the compressor last after that.

airsystem »13 Sep 2013, 15:45

it's real to replace, especially if the bearings just whistle and the steam is still spinning normally, if it's welded, then everything is much worse, but it's also possible to do
lives long if done right
each manufacturer of screw blocks has its own characteristics

oil seals, bearings will be needed - contact

Alexey »13 Sep 2013, 20:43

Korvet »22 Oct 2013, 12:12

Technology TD "22 Oct 2013, 13:44

Korvet "Oct 22, 2013, 14:10

Technology TD "22 Oct 2013, 14:48

and yes and no, capitalizing just a whistling pair is nice and profitable, and capitalizing a pair that was crookedly collected and after that launched more hemorrhoids and a guarantee is dumb, well, this is my personal opinion,

By the way, about the manuals, I just talked to the client about the presence of water in the oil of the XAS 97 compressor produced by the AC, his thermostat was pulled out, but this is half the trouble, so in the AC he was told that he was not needed there at all and was installed extremely rarely on special order,

and you tell everyone to distribute the manual.

I've “brought out” useful experience from working in the AU and still admire the pictures!

lampolom »22 Oct 2013, 15:18

Technology TD wrote: yes and no, capitalizing just a whistling pair is pleasant and profitable, and capitalizing a pair that was crookedly collected and after that launched more hemorrhoids and a guarantee is dumb, well, this is my personal opinion,

By the way, about the manuals, I just talked to the client about the presence of water in the oil of the XAS 97 compressor produced by the AC, his thermostat was pulled out, but this is half the trouble, so in the AC he was told that he was not needed there at all and was installed extremely rarely on special order,

and you tell everyone to distribute the manual.

I've “brought out” useful experience from working in the AU and still admire the pictures!

I can also stand a lot of things .. but there is nothing about screw restoration ..
for replacing bearings, etc. what are the pitfalls, etc.
there are still some kind of calibration washers. and how you can adjust the gap between the screws. just the brain is not enough. but to experiment with an extra screw no. thanks for answers.

Malfunction and repair of screw compressors. The main malfunctions of screw compressors and do-it-yourself equipment repair

Home page »Publications» Failures and repair of screw compressors. The main malfunctions of screw compressors and do-it-yourself equipment repair

The screw compressor belongs to one of the most efficient types of equipment, thanks to which compressed air is obtained in various industries (mechanical engineering, electronics, woodworking, pharmaceutical, furniture). The features of the operation of compressors, possible malfunctions and methods of repairing equipment will be discussed in our article.

The screw equipment consists of the following main elements:

The huge demand for screw compressors is due to the fact that they have numerous advantages over the use of centrifugal or reciprocating equipment. The main ones are:

• ease of installation and connection;
• continuity of work;
• maximum reliability;
• long operational period;
• the presence of low operating costs;
• obtaining almost ideal air purity;
• minimum energy consumption per 1 m³ of air;
• low noise figure;
• the presence of an automatic control system.

Based on the device of the screw compressor, its principle of operation is as follows:

• when passing by the suction valve and air filter, air flows enter the screw block;
• air is mixed with oil, which circulates in an enclosed space;
• by the action of the screw block, the mixture of oil and air enters the oil separator;
• air is separated from the oil and directed to the compressor outlet;
• oil in a small or large circle through the oil cooler (depending on the temperature of the material) goes back to the screw block;
• the start of the screw block occurs with the help of an electric motor;
• automatic shutdown (or activation) is performed using a pressure switch.

It should be noted that oil in screw equipment performs several functions:

• creates an oil film;
• removes heat;
• distributes air flows;
• provides a gap between the rotors of the screw block;
• lubricates the bearings of the working elements.

During the operation of the equipment, you may encounter its breakdown. We have to resort to repairing screw compressors. The most common hardware failures include:

• the compressor does not turn on well or does not restart;
• the unit does not receive compressed air;
• low equipment performance;
• excessive consumption and oil leakage;
• involuntary opening of a safety valve;
• compressor shutdown by thermostat;
• high blood pressure;
• circuit breaker tripped.

Compressor starts up poorly, does not restart, does not receive compressed air, is characterized by low performance

The main reason for poor start-up of equipment is too low air temperature. You just need to warm up the room in which the compressor is located, and everything will be in order.

The unit does not restart due to poor closing of the suction valve. It must be removed and cleaned. In some cases, it will be necessary to replace the elements.

Lack of compressed air at the compressor outlet indicates that the regulator is closed. The problem can be rectified by testing the pressure switch, which should supply power to the solenoid valve associated with the regulator.

In most cases, the low performance of the unit is associated with the closure of the regulator. But in this case, the cause of the malfunction is the contamination of the regulator. To eliminate this, the suction filter is removed, the regulator is opened and cleaned. The best option is to dismantle the regulator and then clean it.

Excessive oil consumption can be caused by:

• broken oil separator filter;
• Leaking oil separator filter seals.

In both cases, problems are solved by replacing the seals or the filter itself.

If oil is leaking from the suction filter, the regulator is not closed or the pressure is too high in the system. In the first case, the functioning of the regulator and the solenoid valve is checked. In the second case, in addition to checking the regulator and valve, you should carefully inspect the pressure gauge.

Oil leaking into the control panel is caused by oil leaking through the unit flange. This problem is rectified by replacing the compressor O-ring.

A clogged oil separator filter may cause the safety valve to open. Check the pressure drop between the oil separator reservoir and the compressed air line. If necessary, the filter should be replaced.

If there is a pressure that exceeds the maximum set value, the regulator must be checked. There may be no command to close it. Make sure that the solenoid valve is disabled.

The compressor is switched off by the thermostat in the case of:

• malfunctions of the thermal expansion valve;
• insufficient amount of oil;
• malfunction of the drain system.

These problems are solved accordingly as follows:

• the valve is being replaced;
• the oil is topped up to the required level;
• the check valve and oil drain lines are checked.

Circuit breaker tripping is associated with:

• overheating of the electric motor;
• insufficient voltage in the network;
• excessively high room temperature.

When the motor overheats, the relay and the heat dissipation from it are checked. During normal heat dissipation, the reset button is pressed and the compressor restarts.

The same actions are performed also in the presence of insufficient voltage in the network and high room temperature. The only difference is the preliminary check of the voltage and the provision of high-quality ventilation, respectively.

Screw compressor troubleshooting video:

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The compressor grunted in the summer. It doesn't matter which one.
Services without looking, over the phone, estimated the repair at 1.5-2.0 thousand rubles.
I realized that the compressor itself was jammed. The motor hums cannot crank.

I disassemble, it is. Forming in oil. I remove the head, with rings, a piston and a cylinder, complete order.
I take it off the crankshaft, we arrived, badass on the liner.
Since the lubricant is natural (bathroom), then the liner is luminous.
I sand it, change the oil, everything is in order.

Background.
The compressor threshed all day in the heat, stood tilted back.
Oil starvation has done its job.

So everything is extremely simple there.
Change the oil more often and place the compressor evenly, there is nothing to break there.
Yes, and do not forget to drain the condensate.

Satanas wrote:
So everything is extremely simple there.

You are verbatim retelling the Operating Instructions.
Some people, including myself, read it right after purchase, but before using it for the first time.

Satanas thanks for the reminder. Today I finally checked the oil and drained the condensate.

There is nothing to break - oh, if only. But I also spent about the same amount of time on repairs.
The picture buzzes, pumps instead of 8 atmospheres 3 maximum. She removed the cover - one of the plate valves in half. I cut out a plate from a spatula (it could have been from a probe), put it on - it works.

And also from the head not stretched out in time (according to the instructions), it punches the gasket between the head and the valve body.
And the thermals are also turned off, a triple dose of oil is poured. and the most favorite of all is to twist the pressure switch.

Suddenly the compressor stopped pumping at all. 🙁 That is, everything works, but there is no pressure. The cause was a grain of sand under the intake valve. And the repair boiled down to wiping the valve on a new shirt. :-R

Satanas wrote:
Change the oil more often and place the compressor evenly, there is nothing to break there.
Yes, and do not forget to drain the condensate.

And do not forget to drain the condensate too. Our story is the opposite of yours - they handed over the compressor to us and demanded to be repaired under warranty. In addition to the fact that the oil in it did not change and was not topped up even once, it was also found that there was half a bucket of rusty oily water in the 50-liter receiver.

He-Hemul wrote:
She removed the cover - one of the plate valves in half. I cut out a plate from a spatula (it could have been from a probe), put it on - it works.

He-Hemul wrote:
The picture buzzes, pumps instead of 8 atmospheres 3 maximum. She removed the cover - one of the plate valves in half. I cut out a plate from a spatula (it could have been from a probe), put it on - it works.

my case is direct. only I will trample him in the store .. or in the service center.
I do not know how to mess with them yet .. and there is no desire.
ideally, return it altogether. and then again then something will come up ... for Forte - Ketaysky))
undertook to paint the house .. and then, an infection, did not live.

VitaminD wrote:
undertook to paint the house .. and then, an infection, did not live.

oh well ... the foreman is what china, and it has been thundering for more than a year, primers, mastics, waterproofing, paint of various curly foam plates. shop and service, a day of hassle, and so-20 minutes of shame and further rumbles.

ruslan1111 wrote:
and so-20 minutes of shame and further rumbles.

Yes, on weekends there is not much time to repair it .. all the more, maybe that's not the point.
I will open it, I will not fix it ... and I will treat it with the guarantors)

He-Hemul wrote:
She removed the cover - one of the plate valves in half. I cut out a plate from a spatula (it could have been from a probe),

I treated the same trouble yesterday. True, at first I rode through the services, I wanted to find my own. As a result, we had to use the collective farm from the 0.2 mm probe. The width fit perfectly (10 mm), and cut it lengthwise with metal scissors. I shook it, everything is normal.

A year ago I was presented with a 100-liter ABAC, killed.
An autopsy showed that the dipstick had broken off, which sprayed oil from the crankcase along the walls. As a result of working in the oil hunger mode, the connecting rod bushings were gobbled up.
It turned out to be unrealistic to buy a new connecting rod, or even a complete steam generator, and had to work on a collective farm.
I bought two suitable needle bearings, there was no cutter of the required diameter, but I had my own CNC:

I pressed it in, everything works. It looks like the system is capable of working without oil at all, but I did not risk it

Yes, and a note to the hostess.This device has the most awful scheme - the crankshaft is on the motor, the piston is directly on it. Without gears and belts. The induction motor starts very slowly, the whole system is very sensitive to undervoltage.
To make it easier to start the motor, I decided to reduce the compression. Between the crankcase and the cylinder, I laid a gasket ring from an old oil filter from some foreign car. By extending the pins, I can, by pressing the cylinder into the rubber, reduce the volume of the working chamber, thereby increasing the compression ratio. It helped, only now from “zero to 10 atm it pumps not 3-5 minutes, but 7-10 minutes, it suits me

Such an almost trouble-free assistant for gardeners and summer residents as an air compressor also sometimes fails. But do not panic - after mastering the theoretical basics of basic malfunctions, compressor repair will be mastered by anyone.

The air compressor is designed to supply a uniform continuous stream of air, which is pre-compressed by the mechanisms of this unit to a certain pressure. Compressed air is used to drive a variety of pneumatic tools, as well as for other purposes.

The range of possibilities for using a domestic air compressor is very wide:

• it will allow you to abandon electrical tools, instead of which you can purchase cheaper, reliable and safe pneumatic ones: a screwdriver, drill, wrench, cutting machine, scissors and others;
• it can be used when working in the country, in the garage, in the yard;
• It can be used to inflate tires, paint and whitewash, blow off debris, trim shrubs and trees, treat plants with pest control compounds, and more.

The minimum basic compressor configuration includes: a blower (engine and a mechanism for air compression) and a tank for storing compressed gas (receiver).

All units differ only in the type of engine (electric or internal combustion), its power, volume and operating pressure of the receiver. The most common compressors are with an electric motor.

The principle of operation of the compressor: the engine, through a belt drive and a pulley, activates the compression mechanism, which pumps air into the receiver (strong steel thick-walled container).

Inside the cylinder of the compression mechanism, a piston is reciprocated. The bypass valves are installed in the cylinder head. When the piston goes down, the intake valve opens and the exhaust valve closes - air is drawn in. When the piston goes up, the inlet closes, and the outlet opens - the air is pushed into the receiver, where it is compacted to the pressure provided by the compressor design.