Using old refrigeration compressor to inflate car tires is a time-tested way to turn household trash into a useful tool. Unlike cheap Chinese analogues, which often overheat and make noise, the unit from the refrigerator is capable of operating continuously for years. Piston group here it is made with high quality, which ensures reliable pressure even at minimum engine speeds.
The main difficulty lies not in the motor itself, but in properly preparing the system for working with air. The standard refrigeration circuit is designed for freon, and not for atmospheric air, so simply replacing the tubes will lead to rapid failure of the device. You will need to completely re-equip the system, adding oil separator and receiver to stabilize the flow. This is the only way to get clean air without an oil suspension, which can damage tires or tools.
In this article we will analyze in detail the process of transforming a household unit into a full-fledged supercharger. You will learn about the nuances of electrical connections, the choice of materials for the receiver and filtration methods. A correctly assembled unit will allow you to forget about problems with tire pressure and will provide you with a source of compressed air for garage work.
The operating principle and features of a refrigeration compressor
The basis of the device is a sealed unit, inside which an electric motor is located and compression installation. During normal operation, the refrigerator sucks in gaseous refrigerant and pumps it into the condenser under pressure. For our purposes, it is important to understand that suction pipe and the discharge have a different design and location. An incorrect connection will result in the device running idle or creating excess pressure inside the housing.
The uniqueness of such motors lies in the lubrication system. The oil is located in the lower part of the housing and is sprayed by the crankshaft or supplied under pressure. When working with air, it is important to prevent its intensive entrainment into the pneumatic system. Therefore horizontal position the housing is a critical operating condition. Tilt or inversion of the device will disrupt the circulation of lubricant, which will cause overheating and jamming of the piston group.
⚠️ Attention: It is strictly forbidden to start the compressor without connecting to the system or with blocked pipes. The pressure inside the sealed housing may exceed the strength of the welds, which will lead to an explosion.
The performance of the unit directly depends on its volume and the condition of the windings. Old Soviet-made models are often more powerful than modern analogues, but require a more thorough revision of the electrical part. Start relay and thermal relay must match the engine power, otherwise the protection system will constantly turn off the power.
Necessary materials and tools for assembly
To create a high-quality supercharger, you will need not only the motor-compressor itself, but also a number of additional components. Particular attention should be paid to the container for storing compressed air - receiver. Old fire extinguishers, freon gas cylinders, or specially welded tanks made of thick-walled pipes are often used as it. The main requirement is the ability to withstand pressure of at least 10-15 atmospheres with a margin of safety.
The list of necessary components includes:
- 🔧 Compressor from the refrigerator (with a power of 100 W).
- ⚙️ Receiver (metal cylinder with a volume of 10 liters or more).
- 💨 Oil separator (you can use a transparent water filter).
- 📏 Manometer for control pressure in the system.
- 🔌 Automation (pressostat or pressure switch).
- 🛠️ Fittings (ball valves, check valves, copper tubes).
It is important to choose the right connecting elements. Copper tubes from the refrigerator itself are often brittle, so it is better to replace them with more flexible high-pressure hoses or copper tubes of larger diameter. Check valve This will prevent the reverse flow of air from the receiver into the compressor when it stops, which will save the mechanism from water hammer with oil.
Don't forget about the tools: a soldering iron with solder for copper pipes, a set of keys, a drill for drilling holes in the receiver and sealant for threaded connections. The quality of assembly directly affects the safety of operation, so you should not save on seals fittings.
Preparation of the compressor and oil change
The first stage of assembly is the preparation of the unit itself. The factory version of the compressor is filled with special mineral or synthetic oil, which may be incompatible with the rubber seals of the pneumatic system or simply too viscous for our purposes. Although a complete oil change in a sealed housing is difficult, it is necessary to check its level and condition.
To do this, carefully cut off the upper part of the housing or, in a more gentle option, bite off a sealed tube that goes deep into the housing (usually this is the longest tube going down). Through it you can drain the old fluid and fill in the new one. It is recommended to use synthetic compressor oilwhich foams less and works better at high temperatures.
| Parameter | Standard value | Recommended for air | Note |
|---|---|---|---|
| Oil type | Mineral / Freon | Synthetic (ISO 46-68) | Reduces carbon formation |
| Volume | 300-400 ml | Up to the mark on the dipstick/body | Do not fill to the brim |
| Flash point | ~180°C | > 220°C | Safety during heating |
| Viscosity | High | Medium | For better cold start |
After replacing the fluid, it is necessary to restore housing tightness. If you cut off the top cover, you need to weld it back or put it on a heat-resistant sealant and tighten it with bolts, if the design allows. Checking for leaks is carried out with a soap solution: apply foam to all joints and turn on the compressor for a couple of seconds. The appearance of bubbles will indicate a place that requires additional sealing.
⚠️ Attention: When working with an open compressor, maintain cleanliness. Getting dust or metal shavings inside the piston group is guaranteed to lead to rapid wear of the cylinders.
Assembling the pneumatic system and installing the receiver
The most critical stage is the integration of the compressor with the receiver. The air from the injection pipe should not go directly into the tire; it needs to settle in the tank. This will allow condensation and oil vapor to settle. The connection diagram is as follows: Compressor → Check valve → Receiver → Outlet tap → Oil separator filter → Inflator hose.
Fire extinguishers with a volume of 10-20 liters are excellent as a receiver. They must be checked for corrosion before use. Rinse the inside of the container with water and dry it. A fitting for connecting the compressor is welded or cut into the upper part of the cylinder, and a tap for draining condensate is welded into the lower part. Check valve It is placed immediately after the compressor, before entering the receiver, so that the air does not escape back when the engine stops.
☑️ Checking the receiver
To connect the copper tubes of the compressor to the system, use threaded adapters. Copper is easy to solder, but connecting to a steel cylinder requires quality fittings. Make sure that all connections are tight and the hoses are not kinked. Pressure In the system, when inflating the wheel, it is usually 2-3 atmospheres, but the receiver should be designed for much higher values in case the automation fails.
It is additionally recommended to install a pressure gauge directly on the receiver. This will allow you to visually monitor the process of air accumulation and timely notice a drop in pressure, indicating a leakage or malfunction of the valves.
Electrical circuit and automatic connection
To automate the process of inflating wheels, it is necessary to eliminate the human factor. It is inconvenient to constantly monitor the pressure gauge, so a pressure switch (pressostat) is installed. This device opens the electrical circuit when the pressure in the receiver reaches a set value (for example, 6 atmospheres), and closes it when the pressure drops below a threshold (for example, 4 atmospheres).
The electrical connection diagram includes:
- ⚡ Plug s grounding for connection to a 220V network.
- 🔌 Pressure switch with a contact group designed for motor current.
- 🛡️ Start relay (standard from a refrigerator or universal).
- 🔥 Thermal relay to protect against overheating of the windings.
- 🔘 Switch power supply for emergency stop.
Standard The refrigerator start relay often works in conjunction with a capacitor. When assembling a new circuit, it is important to save this connection or use a ready-made automation unit for compressors. The wires must have a cross-section of at least 1.5 mm², since the motor starting current can be significant. All electrical connections must be insulated and protected from moisture.
What will happen if you do not install a pressure switch?
Without a pressure switch, the compressor will work until the engine burns out or the receiver bursts. The pressure will rise to critical, which is extremely dangerous. The pressure relay is the main safety element that cannot be excluded from the circuit.
When assembling the electrical part, follow the rule: first assemble the control circuit (relay), then connect the load (motor). Be sure to use a fuse in the power circuit. If you are not confident in your knowledge of electrical engineering, it is better to invite a specialist, since working with high voltage compressed air requires double caution.
Air filtration and oil separation
One of the main problems of refrigerator compressors is oil carryover. In normal mode, freon circulates along with the oil, and this is normal. But when inflating tires, oil gets into the tire, destroys the rubber and can damage the connected tools (spray guns, pneumatic tools). Therefore, installing a high-quality oil separator oil separator is mandatory.
The simplest oil separator can be made from a transparent water filter or a special automobile separator filter. The principle of its operation is based on changing the flow speed and direction of air movement. A fine-mesh mesh or packing (glass wool, metal shavings) is installed inside the filter, on which drops of oil settle.
⚠️ Attention: Regularly check the oil level in the separator filter. An overfilled filter will become a source of contamination, and oil will return to the system. Also monitor the condition of the filter element.
In addition to oil, the air contains moisture. When compressed in the receiver, it condenses. To prevent water from getting into the wheel, you can install silica gel filter or a simple automotive fine filter at the outlet of the receiver, in front of the hose. This is especially true if you plan to use the compressor for painting or sandblasting, where air purity is critical.
Safety precautions and operation
A homemade compressor is a source of increased danger. A pressure of 8-10 atmospheres has enormous energy. Never exceed the operating pressure that your receiver and hoses are rated for. Regularly, at least once a month, inspect all connections, hoses and electrical wires for damage.
When operating, follow the following rules:
- 👓 Use safety glasses when working with pneumatics.
- 🌡️ Monitor the temperature of the compressor housing (no more than 90°C).
- 💧 Regularly drain the condensate from the receiver through the bottom tap.
- 🚫 Do not direct the air stream at people or animals.
The device should be stored in a dry room, protected from dust and moisture. If the compressor is rarely used, before long-term storage it is recommended to drain the oil (if the design allows) or preserve the system. Remember that rubber hoses over time they age and crack, so they need to be replaced as signs of wear appear.
By following these simple rules, you will get a reliable and durable tool for the garage. A refrigerator compressor, properly assembled and configured, will serve you for many years, providing comfortable inflation of tires and work with pneumatic tools.
Is it possible to use a compressor without a receiver?
Theoretically it is possible, but it is highly not recommended. Without a reservoir, the air flow will pulsate, making it difficult to inflate the tires evenly. In addition, the compressor will turn on and off too frequently with each pressure change, which will quickly damage the starting equipment and the engine. The receiver also serves as an air cooler.
What is the maximum pressure that the compressor from the refrigerator develops?
Most household refrigeration compressors are capable of creating a pressure of up to 15-20 atmospheres. However, 2-3 atmospheres are sufficient to inflate tires, while pneumatic tools usually require 6-8 atmospheres. You should not chase the maximum values, as this increases the load on the seals and the risk of breaking the connections.
Do you need to change the oil in the compressor right away?
If the compressor is taken from a working refrigerator, you don’t have to change the oil, but it is advisable to add it to the required level, since some could remain in the system. If the compressor is old, rusty, or you do not know its history, a complete oil change and flushing with kerosene is necessary.