How to make a compressor from a refrigerator with your own hands: from disassembly to testing

An old refrigerator that has served its purpose is often sent to a landfill - but its “heart” can get a second life. A refrigerator compressor, with proper modification, turns into a powerful tool for inflating tires, painting, sandblasting, or even a mini-compressor station. In this article, we will look at how to remove the unit, adapt it for new tasks and avoid common mistakes that lead to breakdowns or injuries.

Before you get to work, evaluate the feasibility: not every compressor is suitable for your needs. For example, models from Soviet refrigerators (ZIL, Minsk, Biryusa) can withstand high loads, and modern inverter units (LG, Samsung, Bosch) may be too “delicate” for the garage. We will focus on universal solutions that work with 90% of household compressors.

Important: if you plan to use a homemade compressor for painting work or sandblasting, some modification will be required oil and moisture filtration systems. About this in the corresponding section.

1. Which compressor is suitable for conversion?

Not all refrigeration compressors are equally useful. Main selection criteria:

• 🔧 Compressor type: optimal piston models (marking begins with KV, DH, F or S). Scroll and rotary (scroll compressors) are more difficult to adapt.
• ⚡ Power: 140–180 W is enough to inflate tires, for painting you need a unit from 250 W. The power is indicated on the nameplate (for example, 220V 1.2A → ~260 W).
• 🛠️ Condition of the starting relay: if the compressor hums, but does not pump, the problem may be start relay (replaced after 200–500 ₽). If it does not start at all, check the windings with a multimeter.
• 💧 Oil: in older models (Donbass, Atlant) mineral oil is used, in new ones (Indesit, Liebherr) - synthetic. Cannot be mixed!

The best “donors” for homemade products:

Critical detail: compressors from refrigerators with the system No Frost often have a built-in pressure relief valve that operates at 8-10 atm. For inflating tires to 2-3 atm this is not a problem, but for a paint gun (required). 4–6 atm) you will have to modify the system.

⚠️ Attention: Compressors from refrigerators electronically controlled (for example, Bosch KGE39AW25R) may have non-standard power connectors. Before disassembling, take a photo of the connection diagram or find a datasheet for the model.

2. Tools and materials: what will you need?

To remove and modify the compressor, prepare:

Phillips screwdriver (PH2)

Open-end wrenches (10–17 mm)

Pipe cutter or hacksaw for metal

Blowtorch or gas torch

Multimeter (for checking windings)

File and sandpaper (grain 120–240)

High pressure hoses (internal diameter 6–8 mm)

Clamps (16–25 mm)

Receiver (fire extinguisher or gas cylinder for 10–50 l)

Pressure gauge (up to 10 atm)

Filter-moisture-oil separator (optional)

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Materials for assembly:

• 🔌 Electrics: PVA cable 3×1.5 mm², plug, socket with grounding, automatic 10 A. For compressors more powerful than 300 W - cable 3 × 2.5 mm².
• 🛢️ Oil: compressor (for example, Shell Corena P 46) or semi-synthetic for refrigerators (Reflube RL-32). motor!
• 🔧 Fasteners: M8–M10 bolts for fixing the compressor to the frame, rubber gaskets for vibration isolation.
• 💨 Additional: check valve (to prevent pressure loss), reducer with a pressure gauge (if pressure control is needed).

Cost of materials (excluding receiver): ~1,500–3,000 ₽. The most expensive element is a filter-moisture-oil separator (from 800 ₽), but without it the compressor will quickly fail. painting.

⚠️ Attention: If you use a fire extinguisher cylinder as a receiver, check its connection to the compressor for leaks. Fill it with water and leave for a day - if drops appear, the cylinder is unusable! to connection to the compressor. Fill with water and leave for a day - if drops appear, the bottle is unusable!

Screwdrivers and keys

Blowtorch

Multimeter

Receiver (cylinder)

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3. Disassembling the refrigerator and removing the compressor

Before disassembling unplug the refrigerator and let it stand for 24 hours - this is necessary to bleed the refrigerant. Working with the system under pressure is dangerous!

Step by step instructions:

1. Removing the back panels: unscrew the screws (usually 4-6 pieces) and carefully remove the cover. In some models (Samsung RB30J3000WW), the panel is secured with latches - pry it off with a flat screwdriver.
2. Disconnecting the tubes: the compressor is connected to the condenser and evaporator with copper tubes. Cut them with a pipe cutter, moving 10-15 cm from the compressor body (useful for connecting hoses).
3. Disconnecting the electrics: take a photo of the wiring diagram to starting relay, then disconnect the terminals. Check with a multimeter that there is no voltage!
4. Dismantling. compressor: unscrew 3-4 bolts securing it to the frame. Be careful - there is oil left in the housing (about 200-300 ml).

After removal, clean the compressor from dust and oil. Check the integrity of the housing - cracks or dents can lead to depressurization.

What to do if the tubes do not bite off?

If the copper tubes are “stuck” to the compressor, heat the joint with a soldering iron. lamp for 1-2 minutes. Do not overheat the housing - this may damage the seals. After heating, the tubes will detach without effort.

Important: Do not throw away the starting relay and capacitor (if it is external) - they will be needed to connect the compressor to the network. In modern models, the relay is often built into the housing (for example, in Danfoss NL), so dismantle it. carefully.

4. Preparing the compressor for operation: changing the oil and checking

Refrigeration oil loses its properties over time, and when altered, moisture and dirt get into it!

How to drain the old one. oil:

1. Place the compressor on a flat surface with the oil hole facing down (usually it is closed with a hexagon plug).
2. Unscrew the plug and drain the oil into a container If the oil is dark or metallic. chips - the compressor is worn out and may soon fail.
3. Rinse the housing with kerosene or gasoline (fill in 100 ml, screw in the cap, pump the compressor and drain). Repeat 2-3 times.

Refilling with new oil:

• 🛢️ Fill the oil through the same hole to the level ½ from the height of the viewing window (if any). For compressors without a window - 200–250 ml.
• 🔄 Turn the compressor shaft manually (by the pulley or using a screwdriver through the hole) - this will distribute the oil over the internal surfaces.
• 🔌 Connect the compressor to the network for 1-2 minutes (without load), then drain the oil and fill with fresh oil - this will remove the remaining flushing fluid.

Checking functionality:

• Connect the compressor via the starting relay to the network. It should start with a characteristic click of the relay and begin to pump air.
• Measure the current consumption with a multimeter (in AC 10Amode). Standard: 1.5–3A for household models. If the current is higher, an interturn breakdown of the winding is possible.

⚠️ Attention: If the compressor does not start, check the starting relay. In 60% of cases, the problem is in it, and not in the unit itself. Relays from Danfoss or Embraco are interchangeable with most household compressors.

5. Assembling a compressor unit: diagrams and nuances

There are 3 main connection diagrams for a homemade compressor:

Consider the assembly universal circuit with a receiver (suitable for 90% tasks):

1. Connecting hoses:
   • To inlet pipe (usually it is thinner) connect a coarse filter (you can use a fuel filter from a car).
   • K outlet pipe —high pressure hose leading to the receiver.
2. Installing a check valve: mounted between the compressor and the receiver. Prevents air from bleeding back into the compressor when stopped.
3. Receiver connection: connect the cylinder to the compressor via copper tube or flexible hose. The cylinder must have:
   • Manometer (shows the pressure in the receiver).
   • Safety valve (adjustable to 8–10 atm).
   • Moisture-oil separator (if the compressor will be used for painting).

Electrical connection:

• Connect the compressor to the start relay by original circuit (see photo taken with disassembly).
• Connect to the network via a 10A circuit breaker. Grounding is required —the compressor body is metal!

Important: All hose connections fix metal clamps - plastic ones can burst under pressure. To seal threaded connections, use FUM tape or anaerobic sealant.

6. Testing and first starts

Before full operation, carry out 3 tests:

1. Check for leaks:
   • Start the compressor and apply a soap solution to all connections. If bubbles appear, tighten the clamps or rewind the threads.
2. Pressure control:
   • Pump the receiver to 4-5 atm and turn off the compressor. If the pressure drops faster than 0.5 atm in 10 minutes, look for a leak.

Checking the oil:

• After 10-15 minutes of operation, drain some oil through the plug. If it is cloudy or has bubbles, there is moisture left in the system. It is necessary to repeat the washing.

Typical problems during the first start:

• 🔥 The compressor gets hot: it is normal if the case temperature is up to 60–70°C. If it’s hot, check the oil level or load.
• 💨 Low pressure: the filter may be clogged or the check valve is faulty. Blow out the system.
• ⚡ The machine knocks out: short circuit in the windings or the starting relay is faulty. Check with a multimeter.

If the compressor operates stably, you can start operating. For painting, it is recommended to install a gearbox with a pressure gauge at the outlet of the receiver - this will allow you to accurately regulate the pressure.

7. Modifications for specific tasks

The basic assembly is suitable for inflating tires or blowing out, but for other tasks modifications will be required:

• 🎨 For painting:
  • Install additional fine filter (for example, Fubag CF400).
  • Use moisture-oil separator with automatic condensate drain.
  • Outlet pressure: 2.5–3 atm (for HVLP spray gun).
• 🏗️ For sandblasting machine:
  • Replace standard hoses with abrasion-resistant (for example, with polyurethane braid).
  • Increase the volume of the receiver to 50–100 liters for a stable air supply.
  • Add pressure relief valve by 8 atm - sand creates additional load.
• ⚙️ For pneumatic tools:
  • Connect pressure regulator with pressure gauge (for example, Condor MPR-02).
  • Use quick-release connections for easy connection tool.

For long-term operation (more than 30 minutes) it is recommended:

• Install the compressor on rubber shock absorbers to reduce vibration.
• Add blowing fan (possible from a computer power supply) for cooling the case.
• Connect automatic shutdown timer (for example, Theben TM 24) to prevent overheating.

⚠️ Attention: When using a compressor for sandblasting never direct the jet at yourself or other people —sand particles at a speed of 200+ km/h penetrate the skin and can cause serious injuries. Wear safety glasses and a respirator!

8. Maintenance and increasing service life

Homemade. the compressor requires regular maintenance:

Action	Frequency	Notes
Checking the oil level	Every 10 hours of operation	Add to the middle of the inspection window
Changing the oil	Every 50–100 hours	Use only compressor oil
Cleaning the filter	Every 20 hours	Blow with compressed air or wash with gasoline
Checking belts/pulleys	Every 30 hours	If worn, replace (belt cost ~200 ₽)
Draining condensate from the receiver	After each use	Ignoring leads to corrosion of the cylinder

Signs that the compressor requires repair:

• 🔊 Increased noise or knocking —wear of the piston group or bearings.
• 🌡️ Case overheating (more than 80°C)—failure of windings or low oil level.
• 💨 Decreased performance —filters clogged or valves are worn out.

If the compressor starts to “pop” at startup or does not gain pressure, it is most likely broken check valve or start relayThese parts are easy to replace yourself (cost 300–800). ₽).

FAQ: Frequently asked questions about homemade compressors

Is it possible to use a compressor from an air conditioner instead of a refrigerator?

Technically, yes, but there are nuances: compressors from air conditioners (for example, Mitsubishi Electric) are designed for a different type of refrigerant and often have a higher operating pressure (up to 25–30 atm). They are more difficult to adapt for household tasks due to:

• Lack of standard pipes for connecting hoses.
• Higher requirements for oil (synthetics are needed POE).
• Difficulties with starting relay (often integrated into the control board).

If you have experience working with refrigeration equipment, you can try, but for beginners it is better to start with a compressor from a refrigerator.

What volume of receiver is needed for painting a car?

Minimum volume of receiver for painting a car — 50 liters. Optimal - 100 liters. This is due to:

• Air pulsation data-i="340">: with a volume of 50 liters, the compressor will turn on every 1–2 minutes, which leads to overheating.: a small receiver does not smooth out pressure surges, which leads to uneven paint deposition.
• Operating time: with a volume of 50 liters, the compressor will turn on every 1-2 minutes, which leads to overheating.
• Coating quality: for basic painting, a stable pressure of 2.5–3 atm is required, which is easier to achieve with a large receiver.

Budget option: tie two fire extinguisher cylinders (20 liters each) in parallel.

What will happen if you do not change the oil in the compressor?

Ignoring oil changes leads to:

1. Increased wear of the piston group (metal shavings act as an abrasive).
2. Overheating - old oil loses thermal conductivity.
3. Compressor jamming - the most common reason for failure building.
4. Oil getting into the air line - this will ruin the painting work (greasy stains will remain on the paintwork).

The service life of the compressor without changing the oil is reduced by 3–5 times.

Is it possible to connect a compressor from a refrigerator to a generator?

Yes, but with reservations:

• Generator power it must be at least 1.5 times higher than the power of the compressor (for example, for a 300 W unit you need a 500 W generator).
• Voltage stability: compressors are sensitive to surges. Use a generator with AVR (automatic voltage regulation).
• Starting under load: if the compressor is connected to the receiver, the generator must withstand starting currents (3–5 times higher than rated).

It is better to avoid long-term operation of the compressor from the generator - this reduces the life of both devices.

Where can you get a compressor from a refrigerator for free?

Sources:

• Scrap metal collection points: they often give away refrigerators for free if you disassemble them yourself.
• Ads “I’ll give it away for free” on Avito, Yule or local boards Search for: “refrigerator for spare parts”, “old refrigerator removal.”
• Refrigerator repair shops: sometimes they give away faulty compressors (specify that a working unit is needed).
• Household appliance landfills: permission is required, but you can find rare models (for example, Danfoss SC15).

Tip: Take Soviet-made refrigerators (ZIL, Minsk, Biryusa) - their compressors more reliable and easier to modify.