The situation when there is excess refrigerant pressure in the refrigeration chamber is rare, but can cause serious damage to the compressor or even depressurization of the system. The owner of household appliances may encounter the need bleed off excess freon after unqualified repairs, when the technician filled the circuit “by eye,” or as a result of diagnostic errors. An excess amount of working substance disrupts the thermodynamic cycle, causing the refrigerator to stop freezing and the compressor to work with overload.
Before proceeding with any actions with pipes and valves, it is necessary to clearly understand the physical nature of the process. Freon the system is under pressure, which varies depending on the ambient temperature and the phase of the substance (liquid or gas). Improper removal of refrigerant can lead not only to damage to equipment, but also to injury, since the gas stream has an extremely low temperature. In this article we will analyze in detail the algorithm of actions, the necessary tools and precautions.
Independent intervention in a sealed circuit requires specialized equipment, such as a pressure gauge station and a vacuum pump. Without these devices, it is impossible to complete the procedure correctly. Releasing freon into the atmosphere is prohibited by environmental standards in most countries, so all work must be carried out using recovery equipment or in well-ventilated technical areas. If you are not confident in your abilities, it is better to contact professionals licensed to work with refrigerants.
Signs of an excess of refrigerant in the system
It is possible to determine that more gas is circulating in the circuit than is provided by the factory parameters using a number of indirect signs. The first alarm bell is often the unnaturally loud operation of the compressor, which is trying to push liquid through the narrow channels of the capillary tube. The pressure on the suction side may be higher than normal, which is easy to track if it is connected to the system pressure gauge. However, visual diagnostics also give important clues to an attentive observer.
If there is a strong excess of freon, the liquid phase of the refrigerant may not have time to completely evaporate in the evaporator and enter the compressor. This phenomenon, known as “water hammer,” is extremely dangerous for engine mechanics. You may also notice that the condenser (the grill at the back of the refrigerator) heats up unevenly or, conversely, remains cold while the compressor heats up. The temperature inside the chambers may not drop to the set values, despite the continuous operation of the unit.
⚠️ Attention: If you notice that the compressor vibrates strongly, hums with a metallic tint, or turns off a few seconds after the thermal relay starts, immediately unplug the refrigerator. Further operation in this mode is guaranteed to lead to jamming of the piston group.
For accurate diagnostics, it is necessary to connect measuring instruments. Normal pressure depends on the type of refrigerant used (R134a, R600a, R407c) and the ambient temperature. Comparing the readings with tabular data for a specific model will allow us to conclude that it is necessary to adjust the amount of the substance. Below is a table of approximate pressures for different types of freons at an ambient temperature of +25°C.
| Refrigerant type | Suction pressure (bar) | Discharge pressure (bar) | Features behavior |
|---|---|---|---|
| R134a | 0.8 - 1.2 | 8.0 - 10.0 | High discharge pressure |
| R600a (Isobutane) | 0.4 - 0.6 | 4.0 - 6.0 | Explosive, low pressure |
| R407c | 3.5 - 4.5 | 14.0 - 16.0 | High pressure, mixture of gases |
| R22 (outdated) | 4.0 - 5.0 | 15.0 - 18.0 | High performance |
Necessary tools and preparation of the workplace
High-quality performance of work on servicing the refrigeration circuit is impossible without a specialized set of tools. The basic element is manometric manifold station, which allows you to control pressure in real time. To bleed gas, you will need a hose of the appropriate diameter and color (usually blue for low pressure), as well as adapters for connecting to a service fitting or soldered tube. If there is no fitting, you will need a gas burner to insert the valve.
Since it is impossible to simply release gas into the room, a cylinder for collecting freon or a recovery system is needed. At home, craftsmen often use special containers, but this requires strict safety measures. You will also need safety glasses and gloves, since contact with liquid freon causes instant frostbite to the skin. Do not forget to prepare scales to accurately weigh the amount of substance being removed if high accuracy is required.
☑️ Preparation for bleeding freon
The workplace must be organized taking into account safety precautions. The refrigerator should be moved out into the open space, providing access from all sides. Ventilation in the room it should be forced, since many types of freons are heavier than air and can displace oxygen, creating a risk of suffocation in the lower part of the room. Remove flammable objects from the work area, especially if an open flame is used for soldering.
Bleeding technology through a service fitting
The most civilized and safe way to remove excess gas is to use a standard service fitting, which is often installed on at the manufacturer's suction line of the compressor. This element is a short piece of copper tubing with a soldered end or threaded valve. To begin work, you must carefully remove the cap or cut off the sealed tip of the tube, being careful not to damage the thread.
Next, the hose from the pressure gauge station is screwed onto the fitting. Before fully tightening, it is recommended to slightly open the valve on the manifold so that the gas flow displaces the air from the hose, and quickly close it. This will prevent atmospheric moisture and oxygen from entering the system. After connecting, slowly open the valve, monitoring the readings of the pressure gauge arrow. Bleeding should occur in small portions.
⚠️ Attention: If the pressure in the system decreases sharply, moisture may freeze in the tubes or oil from the compressor may enter the hose. Open the valve smoothly, pausing to stabilize the indicators.
The process of gas removal is controlled by the pressure drop to standard values. As soon as the pressure gauge needle has reached the required mark corresponding to the evaporation temperature, the valve is closed. The hose is disconnected and the service fitting is immediately sealed. It is important to prevent the compressor from operating when the system is depressurized, otherwise it will suck in air and moisture, which will lead to the formation of an acidic environment inside.
What to do if there is no fitting?
If your refrigerator does not have a service port, it must be cut in. To do this, cut the tube, solder in a brass nipple, and only after that connect the pressure gauges. This is a standard procedure for any repair related to the replacement of freon or a compressor.
Method of inserting a Schrader valve in the absence of a port
In older models of refrigerators or budget-class units, service fittings may be missing. In this case, the only solution is to insert a valve type Shredder (processing). To perform this operation you will need a gas torch, solder, flux and the valve itself. First, a neat cut or puncture is made in the copper tube of the suction line, into which the base of the valve is inserted.
The joint is thoroughly heated with a torch and sealed with soft or hard solder, depending on the material of the tube. It is critical not to overheat the tube so that carbon deposits do not form inside, which can subsequently clog the capillary. After the soldering area has cooled, a pressure gauge hose is screwed onto the valve. From this moment on, the system is ready to control pressure and bleed off excess.
After completing all work to adjust the amount of freon, the Schrader valve must be dismantled. The tube is cut above the insertion point and sealed “tight”. The tightness of the seam is checked with a soap solution or a leak detector. Poor soldering will cause all the refrigerant to quickly leak out and cause the refrigerator to fail again in a few days or weeks.
Risks and safety measures when working with gas
Working with refrigerants is associated with a number of risks, ignoring which can lead to serious consequences. Firstly, many modern freons, such as R600a (isobutane)are flammable gases. At concentrations in air above 4-5%, the mixture becomes explosive. Therefore, it is strictly forbidden to carry out work on bleeding or refilling such gases in unventilated areas or near sources of open fire.
Secondly, physiological effects. Although modern freons are considered low-toxic, high gas concentrations displace oxygen. In a confined space, this can cause dizziness, loss of consciousness and suffocation. In addition, direct contact with the liquid phase of freon when leaving the cylinder causes thermal burns, similar to burns with boiling water, but with the opposite effect - deep freezing of tissues.
⚠️ Attention: Never check the presence of gas with an open flame. To find leaks, use only electronic leak detectors or soapy water. An open fire in the presence of freon can lead to the formation of phosgene, a deadly chemical warfare agent.
The third aspect is environmental responsibility. The release of freons into the atmosphere contributes to the destruction of the ozone layer and the strengthening of the greenhouse effect. Professional refrigeration operators are required to collect waste gas in special cylinders for subsequent disposal or regeneration. Household bleeding, although it occurs, is a violation of environmental standards.
Completion of work and checking the tightness
After it has been possible to bleed off the excess amount of freon and the pressure has been returned to normal, the stage of final sealing of the system follows. If a service fitting was used, it is sealed. If the valve is cut in, it is dismantled and the tube is sealed. The quality of the soldering is a key factor in the longevity of the repair. The seam must be smooth, without cavities and pores, completely melting the parts being connected.
A mandatory procedure is to check for leaks. To do this, the system can be pumped with nitrogen to a pressure of 10-15 bar and left for several hours, monitoring the pressure gauge. A drop in pressure will indicate the presence of microcracks or poor-quality soldering. It is also effective to use a soap emulsion, which is generously lubricated at the joints; the appearance of bubbles indicates a leak.
Only after making sure of complete tightness can you connect the refrigerator to the power supply. The first start is carried out under control: listen to the operation of the compressor, check the heating of the condenser and the appearance of cold in the evaporator. If all parameters are normal, the repair is considered successful, and the refrigerator can be returned to normal operation.
Is it possible to bleed off freon by simply piercing the tube?
Theoretically, it is possible, but this is extremely dangerous and not environmentally friendly. A sudden release of gas under pressure can spray oil throughout the room, and the gas itself, being heavier than air, spreads along the floor, displacing oxygen. In addition, you will not be able to control the amount of substance removed, and air and moisture will enter the system, which will require expensive evacuation and replacement of the filter drier.
How much does it cost to remove excess freon in a workshop?
The cost depends on the region and type of refrigerant. Typically, technicians charge a fee for visiting and diagnostics, and the bleeding procedure itself is often included in the cost of refueling if it was carried out incorrectly. Separately, this service is priced inexpensively, but requires equipment for gas collection.
Is freon from an old Soviet refrigerator dangerous?
Old refrigerators used freon R12 (dichlorodifluoromethane). It is not flammable, but upon contact with an open flame it decomposes to form phosgene. R12 also greatly destroys the ozone layer. Its release into the atmosphere is strictly regulated by international conventions.
Why does the refrigerator freeze worse after refilling?
Most likely, an error was made with the amount of refrigerant. Either it was filled too little (insufficient performance) or too much (an excess of the liquid phase interferes with heat transfer, the compressor works at the limit). It is necessary to correct the amount of gas through the pressure gauge.
Is it necessary to evacuate the system after bleeding?
If the system remained sealed and you simply bleed the excess through the fitting without depressurizing the circuit completely, evacuation is not required. If the valve was inserted or the system was opened, vacuuming is necessary to remove air and moisture.