We solder the Schrader valve into the refrigerator compressor: a complete guide with photos and diagrams

Problems with the tightness of the refrigeration circuit are one of the most common causes of equipment failure. Schrader valve (aka service port) plays a key role in diagnostics and refilling of freon, but its damage or absence can turn repairs into a nightmare. If you are faced with the need to install or replace this element, do not rush to take the refrigerator to the service: with the right approach, you can perform the operation yourself.

In this article we will analyze not only step-by-step soldering technologybut also the nuances of choosing a valve for specific models compressors (Danfoss, Secop, Embraco), as well as typical errors that lead to repeated depressurization of the system. We will pay special attention safety precautions when working with an open flame and refrigerant —this point is often ignored, although it is critical for health.

Before you take up the soldering iron, make sure that the problem is exactly in the valve. Signs of its malfunction:

• 🔍 Freon leakage — the refrigerator freezes slightly, the compressor works without stopping
• 🛠️ Physical damage —cracks on the valve body or traces of corrosion
• 🔧 Inability to connect the pressure gauge —thread torn or jammed
• ⚠️ Extraordinary sounds —hissing when connecting service equipment

1. Preparation of tools and materials

The success of the operation depends 80% on the quality of preparation. You will need:

• 🔥 Gas burner with flame adjustment (optimally - propane/butane mixture)
• 🛡️ Flux for copper (for example, Castolin 1901 or similar acid-free)
• 🔧 Solder - copper-phosphorus (for copper) or silver (for highly loaded systems)
• 🧰 Keys: open-end 10-12 mm and hexagon for valve fitting
• 🧪 Nitrogen (cylinder with reducer) - for purging the system
• 📏 Calipers - for accurate measurement of the tube diameter

⚠️ Attention: Nor Never use tin-lead solder - it cannot withstand the pressure in the refrigeration circuit and will lead to repeated leakage. For systems with freon R600a (isobutane), solder with a melting point of at least 250°C is required.

Before starting work required bleed the remaining freon from the system! Even a small amount of refrigerant in the air can cause an explosion if it comes into contact with an open flame. To do this:

1. Connect the pressure manifold to the service port
2. Open the low pressure valve and release the gas in a well-ventilated area
3. Close the valve and check the pressure - it should drop to atmospheric

2. Choosing a Schrader valve: compressor compatibility

Not all valves are the same! An error in selection will lead to the fact that you either will not be able to connect a pressure gauge, or the valve will not withstand the operating pressure. Main parameters for selection:

For compressors Asian production (for example, Mitsubishi or Panasonic) valves with metric threads are often required M6×1.0 or M8×1.25. Check this information on the marking on the compressor itself - it is usually indicated next to the service port.

⚠️ Attention: Valves with a plastic body (for example, cheap Chinese analogues) are not suitable for refrigeration systems! They are designed for a maximum pressure of 10-15 bar, while in the circuit when the compressor starts it can reach 25-30 bar.

3. Soldering technology: step-by-step instructions

Now we move on to the most important stage. Follow this algorithm to avoid compressor overheating and repeated leakage:

Unplug the refrigerator at least 12 hours before work|

Close all ventilation openings in the room|

Prepare a fire extinguisher (powder or carbon dioxide)|

Wear safety glasses and Kevlar gloves|

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Step 1. Cleaning the surface

Use fine sandpaper (P400-P600) to clean the soldering area from the oxide film. Treat the surface degreaser (acetone or a specialized composition for refrigeration equipment). Apply a thin layer of flux - it should cover only the joint, without excess.

Step 2. Preheating

Heat the soldering area evenlyby moving the torch flame across circle. For copper tubes with a diameter of 6-8 mm, the optimal temperature is 280-320°C. Control the heating using thermocouples or by the color of the copper (should become cherry red).

Step 3. Soldering the valve

When the solder begins to melt from touch (and not from direct flame!), bring it to the joint. Solder should flow into the gap is enough under the action of capillary forces, and not “spread” on top. For a Schrader valve, a layer of solder with a thickness of 1.5-2 mm.

Step 4. Cooling and checking

After soldering, allow the connection to cool naturally (do not cool with water!). Purge the system with nitrogen under pressure 6-8 bar and check for leaks with a soap solution. If there are no bubbles, you can start vacuuming and filling.

What to do if the solder does not stick?

If the solder does not stick to copper, the reason may be:

1) Insufficient heating (check the color of the metal)

2) Residual freon in the system (more thorough purging with nitrogen is needed)

3) Poor quality flux (use only specialized compounds for refrigeration equipment)

4) Oxidized surface (repeat sanding P400)

4. Typical mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes that ruin all the work. Here are the most common:

• 🔥 Overheating of the compressor — leads to damage to the windings. The maximum temperature of the housing should not exceed 120°C (control with an infrared thermometer).
• 💧 Excess flux - its residues cause corrosion. After soldering, remove the flux with a damp cloth soaked in vinegar.
• 🔧 Incorrect valve installation angle —it should be kept in check up at an angle of 45°to avoid oil accumulation.
• ⚡ Work under voltage —even if the compressor is turned off, the capacitors can retain a charge. Discharge them by shorting the contacts with a screwdriver with an insulated handle.

⚠️ Attention: If you are soldering a valve on a compressor with inverter control (for example, Samsung Digital Inverter or LG Smart Inverter), be sure to disconnect the control board! These models are sensitive to voltage surges that may occur when the case heats up.

Another common problem is clogged valve after soldering. This happens if scale or solder particles get into the system. To avoid this:

1. Blow the tubes with nitrogen to and after solders
2. Use a filter drier with a fine mesh (150 mesh)
3. Install a temporary filter on the suction line before evacuation

5. Leak testing and evacuation

After installing the valve, the system must go through two mandatory tests:

1. Check for leaks - apply nitrogen under pressure 10-12 bar and leave for 30 minutes. Apply soap solution to all connections.
2. Vacuuming — connect the vacuum pump and evacuate the system to pressure -0.9 bar (or 29.9" Hg). Keep the vacuum for at least 15 minutes.

For accurate diagnostics, use electronic leak detector (for example, Inficon D-Tek Select). It is able to detect leaks up to 3 g/year, while a soap solution will show only gross defects.

⚠️ Attention: If after evacuation the pressure in the system rises faster than 0.5 bar 5 minutes, there is a leak somewhere. Do not refill freon until you find and fix the problem!

For compressors with capillary tube (most household refrigerators), the vacuum process has a nuance: first pump out from the side suction, then from the side dischargeThis prevents clogging of the capillary. oil.

6. Refilling freon and test run

After successful evacuation, you can start refilling. To do this:

1. Connect the freon cylinder through the pressure manifold
2. Open the cylinder valve and refill liquid freon (cylinder upside down) for quick filling
3. Control the weight of the refrigerant using electronic scales (permissible error - ± 5 g)

Refilling rates for popular models:

• Atlant/Stinol (R134a) — 90-120 g
• LG/Samsung (R600a) — 50-70 g
• Liebert/Indesit (R134a) — 100-150 g

After refueling, turn on the refrigerator and check:

• 📉 Discharge pressure should be 10-14 bar for R134a and 8-12 bar for R600a
• ❄️ Condenser temperature - the upper part should be hot, the lower part should be warm
• ⏱️ Compressor operating cycle - during normal refueling it should turn off after 8-12 minutes after starting

If the compressor runs without stopping or the condenser is uniformly warm, this is a sign undercharging. If frost appears on the tubes - refilling. In both cases, you need to bleed off the freon and repeat the procedure.

7. Features of working with different types of compressors

Schrader valve soldering technology may differ depending on the design of the compressor Let's consider the key nuances:

For compressors with two service ports (suction + discharge) the Schrader valve is usually installed on the discharge side. The exception is systems with capillary. tubewhere the port can be on the suction side for ease of diagnosis.

⚠️ Attention: In compressors Embraco Fullmotion i Danfoss Maneurop the service port is often closed with a hexagon plug. Do not try to drill it - use the original key so as not to damage the thread.

8. Alternative methods for installing the valve

If soldering is not possible for some reason (for example, there is a risk of damaging the compressor), consider alternative methods:

• 🔧 Threaded adapter - suitable for systems with pressures up to 20 bar. Use an adapter with a tapered thread 1/4" SAE and Teflon. gasket.
• 🔩 Compression fitting —a temporary solution for diagnostics. Requires regular checking for leaks.
• 🔄 Replacing a tube with a port —a radical method when the tube itself is damaged. Requires resoldering. circuit.

For industrial refrigerators (for example, Bitzer or Copeland) is often used flange connections with gaskets made of copper or aluminum B. In this case, soldering is not required - just tighten the bolts evenly with a torque 12-15 Nm.

⚠️ Attention: Compression fittings are strictly not recommended for systems with freon R290 (propane) or R600a (isobutane) due to the risk of ignition if leaked. These refrigerants require only soldered connections.

FAQ: Frequently asked questions about soldering the Schrader valve

Is it possible to solder the valve while the compressor is running?

Absolutely not! Soldering on a running compressor leads to:

• Damage to the stator windings due to overheating
• Risk of explosion of freon residues
• Scale getting into the oil

The compressor must be disconnected from the network at least 12 hours before work, and the freon must be completely bled off.

Which solder is better: copper-phosphorus or silver?

The choice depends on the type of system:

• Copper-phosphorus (for example, Castolin 192) - suitable for copper tubes and standard household refrigerators Cheaper, but requires precise temperature control.
• Silver (for example, Harris Stay-Silv 15) - necessary for highly loaded systems (industrial refrigerators, compressors with pressure >30 bar) Provides a more durable connection.

For freon R290 or R600a be sure to use silver solder - it withstands vibrations and temperature changes better.

What to do if after soldering the valve allows nitrogen to pass through?

Reasons and solutions:

1. Don't solder —heat the connection and add solder. Use flux with an activator (for example, Castolin 1901F).
2. Crack in the body valve —replace the valve. Do not try to solder the crack - this is a temporary solution.
3. The thread is damaged —use a threaded insert (helicoil) or replace the tube with the port.
4. Poor quality valve —cheap analogues often have porous metal. Buy only certified parts (Schrader, Parker).

Do you need to change the oil in the compressor after soldering?

Yes, if:

• You overheated the compressor housing over 120°C
• Moisture got into the system (for example, during prolonged inactivity with an open circuit)
• Acid flux was used

To change the oil:

1. Drain the old oil through the drain pipe
2. Wash the compressor crankcase with a special solvent (R134a Flush)
3. Fill in new oil of the same type as previously (for example, Emkarate RL68H for R134a)

The oil volume is indicated on the compressor nameplate (usually 200-350 ml).

Is it possible to use a propane torch instead of an acetylene one?

Yes, but with reservations:

• A propane torch produces a “softer” flame, which reduces the risk of overheating.
• For soldering copper tubes with a diameter of up to 10 mm, the power of propane is sufficient.
• Not suitable for silver solder with a melting point higher 700°C.

Recommendations for working with propane:

• Use a torch with piezo ignition (for example, Rothenberger Super Fire 2)
• Keep the flame at a distance 15-20 mm from the soldering point
• Avoid prolonged heating of one point (maximum 10 seconds)