How to make a compressor for inflating wheels from a refrigerator

Using an old, but still working refrigerator does not necessarily end with scrapping it. Compressor, which is the heart of the refrigeration unit, has an amazing resource and is capable of creating pressure sufficient to inflate car tires, operate pneumatic tools or airbrush. Many car enthusiasts and DIYers are thinking about how to turn an unnecessary unit into a useful device for the garage. This solution allows you to save a significant amount on the purchase of factory equipment, while obtaining a quiet and durable tool.

The main advantage of this approach lies in the design of the pump itself. Unlike belt-driven piston compressors, which often make noise and vibrate, the refrigerator operates almost silently. It does not require complex maintenance, since all its rubbing parts are in an oil bath and are reliably isolated from the external environment. However, to adapt to inflating wheels, you will need to solve several technical problems related to air purification and pressure regulation. hermetic compressor The refrigerator operates almost silently. It does not require complex maintenance, since all its rubbing parts are in an oil bath and are reliably isolated from the external environment. However, to adapt to tire inflation, you will need to solve several technical problems related to air purification and pressure regulation.

Before starting disassembly, you need to make sure that the source material is in good condition. Not every unit removed from the kitchen is suitable for creating a complete one. The engine should start the first time, run smoothly, without buzzing or strong vibration. If you plan to use the device only for inflating tires, the performance requirements may be lower than for connecting pneumatic tools, but the reliability of the unit remains paramount. compressor station. The engine should start the first time, run smoothly, without buzzing or strong vibration. If you plan to use the device only for inflating tires, the performance requirements may be lower than for connecting pneumatic tools, but the reliability of the unit remains paramount.

Preparation of tools and selection of components

For successful implementation of the project, you will need not only the compressor itself, but also a number of additional components that will ensure the safety and functionality of the finished product. The basic element, in addition to the pump, is receiver a container for storing compressed air. Old fire extinguishers with a volume of 10 liters or more, gas cylinders or even thick-walled large-diameter pipes are often used as a receiver. It is important that the container is metal and can withstand pressure with a reserve.

In addition, you will need a set of plumbing and electrical elements. To connect the nodes you will need copper tubes, high pressure hoses, fittings and clamps. The electrical part includes a pressure switch, which will automatically turn off the motor when a preset limit is reached, and a power cord with a plug. Also do not forget about oil-moisture separatoras compressors from refrigerators tend to throw out oil along with the air, which can damage the painted surfaces or the tire valve mechanism.

⚠️ Attention: When using fire extinguishers as a receiver, make sure that they are completely empty and not are under pressure. Even after many years, residual pressure or aggressive substances may remain inside.

The list of necessary tools for assembly is quite standard for a home workshop. You will need a drill or screwdriver, a set of metal drills, wrenches, screwdrivers, a soldering iron or welding machine (if you plan to overhaul the frame), and a hacksaw. To seal threaded connections, be sure to stock up on fum tape or thread. All these items will help create a reliable design that will last for many years.

• 🔧 A drill and a set of metal drills for making holes in the receiver.
• ⚙️ Wrenches and screwdrivers for installing fittings and electrical equipment.
• 🔌 Pressure switch (pressostat) for automation of work.
• 🛢️ High pressure hoses and clamps for connecting units.
• 🌡️ Pressure gauge for monitoring the pressure in the system.

Dismantling the compressor and primary check

The process of removing the compressor from the refrigerator requires care so as not to damage the outlet tubes and electrical parts. First of all, it is necessary to disconnect the unit from the refrigeration circuit. Copper tubes running from the compressor to the condenser and evaporator are cut with wire cutters at a distance of 5-10 cm from the housing. This will preserve the integrity of the fittings and will facilitate further work with them.

After removing from the refrigerator, the compressor should be cleaned of dirt and dust. Pay special attention to the electrical box attached to the side. Inside it there are starting and protective relays. They must be preserved as they ensure that the engine starts correctly. If you plan to use the compressor in a vertical position (as it stood in the refrigerator), starting problems usually do not arise. However, for a compressor station it is often mounted horizontally on the frame, which may require additional fixation of the relay or the use of special fasteners.

At this stage, it is important to conduct an initial performance test. Connect the compressor to the network via an extension cord and turn it on briefly. You should hear a steady hum and feel a flow of air from one of the tubes. The second tube will suck in air. The third, sealed, is usually used for oil filling and is sealed in a new compressor, but in older models it may have a cap. Flow direction critical for correct installation of check valves in the future.

If the compressor hums but does not start, the piston group may be jammed or the start relay may be faulty. In some cases, replacing the relay with a known good one helps. It is also worth checking the winding resistance with a multimeter. Lack of resistance indicates an open, and too low - an interturn short circuit. In both cases, repairs are not economically feasible, and the unit is better used as a donor of spare parts.

Modernization of the lubrication and filtration system

One ​​of the main problems when using a refrigeration compressor as an air blower is oil mist. Since the compressor crankcase contains oil to lubricate rubbing parts, some of it is inevitably carried away with the flow of compressed gas. This is not critical for inflating tires, but it can stain clothes and the floor in the garage. To work with a spray gun or pneumatic tool, the presence of oil in the air is unacceptable.

To solve this problem it is necessary to install oil-moisture separator. The simplest option is to use a transparent fine fuel or water filter filled with padding polyester or a special filter sponge. A more advanced option is to make a cyclone filter (oil trap), where the air swirls in a spiral, and the oil settles on the walls under the influence of centrifugal force. Such a unit is installed immediately at the outlet of the compressor, in front of the receiver.

It is also worth thinking about the air intake system. An air filter should be installed on the compressor inlet pipe. In factory conditions, this may be a simple foam element, but for garage conditions it is better to use a more serious filter, for example, from a car or motorcycle. This will prevent dust and abrasive particles from getting inside the mechanism, which will significantly extend the service life of piston group.

• 💧 Installing an oil trap at the outlet of the compressor.
• 🌬️ Installing an air filter on the inlet pipe.
• 🔩 Using transparent filter housings to control contamination.
• 🛑 Regular replacement of filter elements.

Some experts recommend completely replacing the oil in the compressor with a synthetic one that is more resistant to oxidation and has less volatility. However, this procedure requires opening the sealed case, which is difficult and risky to do at home. It is easier (periodically) to drain the condensate and oil from the receiver through the drain valve.

Manufacture and preparation of the receiver

The receiver is a container that stabilizes the pressure and allows the compressor to operate in intermittent mode, turning on only when the pressure drops below the set level. As mentioned, the ideal candidate is an old fire extinguisher. It must be carefully prepared before use. First make sure that the pressure inside is equal to atmospheric pressure. Then unscrew the top valve and rinse the container with water and detergent to remove any remaining powder or foam.

After washing, the fire extinguisher must be dried. The internal walls should be treated with an anti-corrosion compound if there is any suspicion of rust. To do this, you can use special primers or even used motor oil, which is poured inside, shaken and the excess is drained. This will create a protective film.

⚠️ Attention: It is strictly forbidden to use plastic containers, household chemical bottles or thin-walled metal canisters for the receiver. They may not withstand the pressure and rupture with the formation of fragments.

In the upper part of the receiver (usually where the fire extinguisher spray was installed), it is necessary to cut a thread or weld a fitting to connect the compressor and shut-off valves. If you use a fire extinguisher with a threaded neck, the task is simplified: you can make or select a cap with welded pipes. A tap must be installed on the lower part of the receiver to drain condensate. Water formed during air compression will accumulate at the bottom and must be removed regularly to prevent corrosion from the inside.

Calculation of the receiver volume

The optimal receiver volume for a garage compressor is from 10 to 50 liters. A smaller volume will lead to the motor turning on too often, which will shorten its life. A larger volume will take up a lot of space, but will provide more stable pressure. To inflate the wheels of passenger cars, 10-20 liters are enough.

The mounting of the receiver to the frame must be reliable. Metal corners or clamps are often used to fit around the body of the fire extinguisher. It is advisable to place rubber gaskets between the metal of the receiver and the frame to dampen vibration and prevent paint abrasion. The entire assembled structure must be stable and not tip over when moving.

Electrical circuit assembly and automation

For automatic operation of the compressor, it is necessary to install a pressure switch (pressostat). This device opens the electrical circuit when the pressure in the receiver reaches the upper limit, and closes it when the pressure drops to the lower value. Standard relays for compressors have a threaded connection to the receiver and terminals for connecting the network and the motor.

The connection diagram is quite simple: the network wire (220V) comes to the relay input terminals. From the output terminals of the relay, phase and zero go to the contacts of the compressor starting relay. It is important to correctly determine the contacts of the starting and operating windings, although in a standard refrigerator relay they are already connected correctly. If you use a native refrigerator relay, then simply connect its output to the motor windings, and the input to the contacts of the pressure switch.

The pressure switch is adjusted using the adjusting screws under the cover. There are usually two screws: one adjusts the cut-out pressure (upper limit), the second adjusts the delta (difference) between on and off. To inflate the wheels, it is enough to set the upper limit to 6-8 atmospheres, and the lower limit to 4-5 atmospheres. This will ensure comfortable operation without overloading the engine.

A mandatory element of the security system is safety valve. If the pressure switch does not turn off the compressor for some reason, this valve will open and bleed air, preventing the receiver from exploding. The system must also have a check valve installed between the compressor and the receiver. It prevents air from leaving the receiver back into the compressor after it stops, which makes it easier to restart the engine.

Final assembly, testing and operation

When all components are prepared, you can begin final assembly. Secure the compressor and receiver to a common frame. The frame can be made of a profile pipe, a wooden panel (if vibration is minimal) or even an old cart for ease of movement. Connect the compressor to the receiver with a copper tube or high-pressure hose, not forgetting to install a check valve and a tee for connecting a pressure gauge and pressure switch.

All threaded connections must be sealed with fum tape. After assembly, perform a visual inspection and a leak test. Turn on the compressor and allow it to build up pressure until the first shutdown. Listen carefully and inspect the joints for leaks. To search for leaks, you can use a soap solution: apply it to the connections and watch for the appearance of bubbles.

During operation, monitor the oil level in the compressor (if there is an inspection window) and regularly drain the condensate from the receiver. Do not operate the compressor at temperatures below +5°C, as the oil may thicken and cause damage. It is also not recommended to operate the unit continuously for more than 20-30 minutes without a break to avoid overheating, although modern models are quite durable.

Frequently asked questions (FAQ)

What is the maximum pressure that a compressor from a refrigerator can develop?

A standard refrigeration compressor is capable of creating a pressure of up to 10-12 atmospheres and even higher, but its performance (volume of pumped air per minute) decreases. Its power is more than enough to inflate passenger car tires (2.0-2.5 atm).

Is it necessary to change the oil in the compressor during refurbishment?

In most cases, the standard oil filled in by the manufacturer is enough for the entire service life. Replacement is only required if the compressor was severely overheated or was operating intermittently. Self-replacement is difficult due to the tightness of the housing.

Can such a compressor be used to paint a car?

Only with a high-quality oil and moisture separator. A conventional refrigeration compressor pumps a lot of oil, which will damage the paintwork. For professional painting, it is better to use specialized compressors, but for local repairs or inflating tires, a home-made option is perfect.

Why does the compressor hum, but does not pump?

Possible reasons: jamming of the piston group, faulty start relay, broken winding or air leakage through the check valve. Also check if the air filter at the inlet is clogged.

How often should you drain the water from the receiver?

Depends on air humidity and intensity of use. In wet weather, it is recommended to drain the water after each use. In dry weather, it is enough to do this once a week or as it accumulates (monitored visually through a transparent hose or by ear when opening the tap).