Do-it-yourself vacuuming of an air conditioner: technology for carrying out the work + valuable recommendations

When buying a split system and calling an installation team to install it, we all want the climate control device to get rid of the heat in the summer, and from the cold in the spring and autumn. And so that it still works properly for at least 6-7 years without maintenance. Is everything right?

If the manufacturer's warranty protects you from factory defects, then from the negligence of installers - only an understanding of the procedure for installing a split system. In 70% of installation work, air conditioning technicians simply do not vacuum the air conditioner, since it takes a long time (about 30-60 minutes) and is expensive (a good vacuum cleaner costs more than 12 thousand rubles).

Meanwhile, this “minor” installation omission seriously affects the service life of the split system. Let's talk about vacuuming air conditioning systems in detail.

Purposes of vacuuming a split system

Most split systems of different brands can easily cope with a six-year or longer trouble-free operation under two conditions. The first is the absence of manufacturing defects in split units. The second one is correct installation of air conditioning system on the spot.

After placing the blocks (outdoor, indoor) in place, connecting the flared ends of the copper pipes with the taps of the external and fittings of the internal split modules, the work of the installers looks complete.

However, before introducing freon refrigerant into the pipe line and turning on the air conditioner, air conditioning equipment manufacturers recommend pumping out the air from the connecting pipes and the circuit as a whole.

Each unit and almost every working element of the refrigeration circuit interacts with the refrigerant. Therefore, the composition of freon should not be affected by either air gases or moisture

So is it necessary to vacuum a home air conditioner or is it an unnecessary operation, as many installers of split systems confidently claim? Let's see.

The working processes of the refrigerant circulating through the pipes and units of the air conditioning device are precisely balanced by the manufacturer. Cycles of compression, condensation and supercooling of freon occur under strictly defined aggregate states of the refrigerant.

The following happens:

• The vaporous refrigerant follows a thick tube from the evaporator (indoor split unit) to the condenser (outdoor unit), where it is pumped by the compressor. There the freon is blown by a fan and cooled;
• The liquefied refrigerant is directed through a thin tube to the evaporator of the indoor unit. Its pressure is reduced by a thermostatic valve;
• In the indoor unit, freon boils and actively evaporates, absorbing heat. The cold heat exchanger is blown by a fan, distributing cooled air throughout the room. The refrigerant is then pumped from the indoor unit to the outdoor unit - the operating cycle is repeated.

But air and moisture mixed with freon change its operating parameters, seriously interfering with the operation of the air conditioner. How do these extra components end up in the refrigerant?

The copper tubes connecting the climate system modules contain air after they are connected to the split units.What is also important is that the air always contains moisture, which also negatively affects the characteristics of the air conditioning device. Let us explain how water and air affect the freon refrigerant and the split system compressor.

Air mixed with freon

Having remained in the tubes of the split system (i.e., evacuation was not performed), atmospheric air accumulates in the condenser of the “street” unit, since the receiver blocks its further passage (as vaporous (uncondensed) freon).

Neither blowing with freon, nor relying on the dryness of the summer atmosphere, nor the assurances of installers - nothing will ensure the long service of your air conditioner except proper installation with vaccummation of the freon line

The collected air in the condenser significantly increases the pressure required to condense the refrigerant. In addition, an air film appears on the condensation surface, which greatly impairs the heat extraction from the condensed freon.

Since heat removal is deteriorated, and the volume of incoming refrigerant remains the same, the condensation pressure increases, requiring an increased compression ratio from the compressor. As a result, an unacceptably high pressure and temperature are observed at the compressor outlet, which sharply accelerates its wear life.

Moisture in air conditioner compressor oil

In addition to the main refrigerant material, the circuit of the split air conditioning system contains synthetic polyester oil. As with other refrigeration equipment, POE oil provides lubrication to the moving parts of the compressor.

The oil intended for lubrication and sealing of compressor units is made on the basis of polyesters. It is contained in the compressor tank.During operation, oil enters the refrigeration circuit in a small volume - about 5-10% of the total amount.

By covering the walls of the refrigeration circuit tubes with a thin layer, the oil film, in addition to heat removal, promotes improved circulation of freon.

A characteristic sign of clogging of the refrigerant in a split system with atmospheric moisture is a frozen pipe for the gas phase of freon circulation

However, ester oils are characterized by high hygroscopicity. If the water content of POE oil exceeds 30 ppm (30 parts per million polyester oil), its performance will deteriorate sharply. This may be followed by jamming of the compressor - the most expensive unit in the split system.

Increased water content weakens the dielectric strength of polyester oil, which will lead to breakdown of the compressor winding.

In the presence of water in the oil at a level above 30 ppm and in the presence of fluorine, chlorine and bromine atoms contained in freon R410, hydrolysis processes develop, causing the formation of active acids - hydrochloric (HCl), hydrofluoric (HF) and hydrobromic (HBr). Even in small volumes, these acids will corrode the refrigeration circuit tubes due to chemical corrosion.

Finally, water that has not been dried by vacuuming and has saturated the synthetic oil will cause internal icing of the thin tube of the freon circuit near the external unit.

This is especially evident when the split system operates for heat during the off-season. As a result, the compressor operates with insufficient refrigerant volume, quickly overheats and shuts down (protection is triggered). In the worst case scenario, the compressor burns out. With rules compressor performance checks The article we recommend will familiarize you with the process of repairing it.

Note that it is impossible to remove moisture from the synthetic oil contained in the air conditioner by vacuuming. One option here is to drain the moisture-saturated POE, replacing it with new oil.

How to evacuate an air conditioner

To perform the procedure for drying and deairing the air conditioner circuit, you will need the following equipment: a manometric (collector) station, also used for filling split systems with freon; vacuum pump; screwdrivers and wrenches.

To let freon into the circuit after evacuation, two hex keys (usually 4 mm) are needed.

It is important to accurately follow the order in which the hoses of the gauge manifold are connected to the outlet fittings of the vacuum pump and the refrigerant cylinder

Let's look at how to vacuum a newly installed (new) two-unit air conditioner in order:

1. We connect the hose (blue color) of the pressure gauge station from the fitting under the low pressure gauge to the service port on the valve of the external unit of the split system (thick tube of the “gas” phase of the refrigerant). The taps on the valves of the split block (opened with a hex key) must be closed;
2. We connect the filling hose (yellow) from the middle fitting of the collector station with the vacuum pump;
3. Turn on the pump;
4. Open the low pressure valve at the pressure gauge station (blue, under the blue pressure gauge). The vacuum process has begun;
5. We wait from 15 minutes to half an hour (the longer the freon line, the longer) until the pressure gauge needle goes below zero;
6. We turn off the pump and wait for maximum purification of the atmosphere in the split system line from moisture and air gases. It will take more than 30 minutes;
7. We close the blue valve at the pressure gauge station, only after that we disconnect the vacuum pump;
8. Without opening the blue valve and without removing the blue hose from the valve on the “street” split block, we open two taps on the external unit of the air conditioner with hex keys and let freon into the circuit. Then you can disconnect the blue hose.

Follow the needle on the blue pressure gauge. As the degree of rarefaction of the atmosphere of the refrigeration circuit increases, it should slide towards zero. Depending on the power of the pump and the length of the freon line, vacuuming will take 15-20 minutes.

Then the pump must be turned off (do not disconnect!) and monitor the pressure gauge needle for 30 minutes. The pressure is maintained - everything is fine, you can fill the circuit with refrigerant. Models of vacuum pumps in the mid-price range and above are equipped with a vacuum gauge scale; using it to track the degree of rarefaction of the atmosphere is especially convenient.

Errors when vacuuming split systems

In the absence of a vacuum meter, air conditioner installers are guided by the pressure data on the pressure gauge - they wait for the needle to drop below the zero mark, after which they complete the vacuumization. This is a deep mistake!

Achieving extreme minus on the low pressure gauge is not the purpose of evacuation. To eliminate moisture, the high-vacuum atmosphere in the circuit should be kept for more than 30 minutes after the pressure gauge goes negative

You should continue to maintain atmospheric rarefaction in the freon circuit for at least half an hour with the pump turned off in order to evaporate and remove moisture from the climate control unit. This operation is called crimping.

If during vacuum crimping the blue pressure gauge shows spontaneous normalization of pressure - the arrow moves from zero to one - depressurization is observed. We check the fastenings of the hoses to the pressure gauge system, to the taps on the outdoor split-block and to the vacuum pump.

The new split system is regularly charged with freon, isolated in the external unit. Having completed the evacuation, without disconnecting the hose from the service fitting (the vacuum in the circuit must be maintained), remove the plugs and open the valves with a hex wrench, allowing refrigerant into the circuit

Having not found a weak fastening between these devices, we look for an installation defect - overtightened or loose nuts on the copper pipes of the line, or poor-quality rolling of their ends.

Evacuation of the refrigerant line is effective if only the temperature in the area where the external air conditioner unit is located exceeds +15^OC. Water at low street temperatures in a rarefied atmosphere does not evaporate, but freezes - it is almost impossible to remove it from the pipe line.

For example, at +30^OC 40 mbar is enough to evaporate the water present in the refrigeration circuit. And at 0^OIt will be necessary to reduce the pressure to a deep vacuum - below 6 mbar, otherwise there will be no evaporation and removal of moisture.

The colder the atmosphere at the location of the external air conditioning unit, the higher the vacuum and the longer the period required to remove moisture before starting the freon circuit

Therefore, evacuation must be performed either in the warm season, or with special heating of the heat exchanger of the external split block (for example, with a heat gun) for the entire time that a vacuum is maintained in the freon line being prepared.

Note that purging the circuit with freon, practiced by careless installers, cannot give the proper result in eliminating air and moisture. This is just a pointless waste of freon, which, by the way, is not cheap.

Pumps for vacuuming split systems

To remove a larger proportion of gaseous substances from the collected, but not yet filled with freon compressor-condensing unit, a special device is required - a vacuum pump. The procedure for pumping air out of a split system can be performed by two main types of pumps – low-vacuum and high-vacuum.

For splits up to 7000 BTU, a single-stage vacuum pump is suitable; for more powerful ones, a two-stage one is needed, and for multi-zone systems, only an ion-getter one. You will definitely need a pressure gauge station with hoses and fittings for 410 freon

Let us repeat once again: it is possible to vacuum the air conditioner yourself, but this work cannot be done without a vacuum pump.

Types of low vacuum pumps:

• Rotary vane (single-stage). They are characterized by low noise during operation, the ability to adjust the residual pressure, and simplicity of design. Their disadvantages are the need to periodically replace consumables (for example, oil);
• Double-rotor (two-stage). Equipped with two main rotors operating synchronously. Economical, effectively “push” air to the drain pipe by increasing the pressure in the circuit of the device being evacuated;
• Water-ring. Capable of removing both air and liquid equally well. The disadvantages of such devices are significant energy consumption and the need for water.

Of the types of vacuum pumps listed above, only in the low-vacuum range (10⁵-10² Pa) only water ring devices work. For other types, the vacuum range is wider and reaches 10^-3 Pa, i.e. high vacuum levels.

Types of high vacuum pumps:

• Diffusion. Highly efficient, provide fast vacuumization. But they cannot be used for the refrigeration circuit, because the working fluid of these pumps is synthetic oils, which contaminate the vacuum circuit;
• Cryogenic. Their work is accompanied by the injection of nitrogen, which freezes and removes gases and liquids while increasing the degree of rarefaction of the internal atmosphere of the circuit;
• Getter ion. Equipped with a thin titanium film that traps molecules of gases and liquids removed from the refrigeration circuit during evacuation. The most effective - eliminate up to 97% of impurities.

Despite the advantages of ion-getter vacuum degassers, which turn off the provision of a high degree of vacuum (over 10^-5 Pa), when installing split systems they are rarely used - these devices are expensive.

Which vacuum cleaner is better to choose?

The choice of the optimal type of vacuum pump depends on the length of the freon line and the power of the air conditioner that needs vacuum cleaning from atmospheric gases. It is also necessary to take into account the dimensions of the pumping device, since it will need to be placed near the external split unit to connect to the evacuation procedure.

This device is capable of vacuuming the circuits of refrigerators, car air conditioners and low-power split systems. For air conditioning equipment with a power of 9000 BTU and above, such a vacuum degasser is not suitable

A significant criterion is the residual (lowest) pressure achieved by the vacuum pump in no-load operating mode (inlet pipe closed).The lower the residual pressure (indicated by the manufacturer in Pa, mbar or microns), the better the vacuum sealer.

The next criterion is the performance of the vacuum pump (indicated in l/h). It determines the volume of gas pumped by the device per hour of operation at a given outlet pressure.

The last important criterion is the power of the electric motor of the vacuum installation (indicated in W). The longer the freon line, i.e. The further apart the split units of the air conditioner are located, the longer it will take to vacuum clean the refrigeration circuit. This means you will need a vacuum cleaner with a fairly powerful engine.

Among vacuum pumps, this type provides the deepest vacuum. If dehumidification and deairing of a multi-meter copper line is required, for example, for VRV and VRF systems, this vacuumizer is needed. However, specialists must work with it; the device is too powerful

Most often, installers of split systems use two-stage and single-plate vacuum pumps. The first ones are considered semi-professional and do a good job of vacuuming household air conditioning systems, while the second ones are the cheapest, although they do not provide good enough evacuation of freon circuits longer than 3.5 m.

Homemade vacuum pump

The vacuum generator can be made on the basis of a compressor from an old refrigerator (Saratov, ZIL, etc.). It is necessary to drain the mineral oil from it, replacing it with pre-washing with kerosene with a more viscous machine oil (summer “synthetics”).

It is possible to make a vacuum pump based on a compressor from a refrigerator, but it is not capable of vacuuming splits more powerful than 5000 BTU. Most of these homemade products (see.photo) are not vacuum degassers, but air compressors

During operation, the compressor will actively eject mineral water through the outlet tube, quickly filling the oil trap. Replacing with “synthetics” will allow you to do without a separate receiver with a filter. But the installation of an oil trap is mandatory. To control the degree of vacuum, you will need a vacuum gauge or, at a minimum, a pressure gauge.

However, if you can assemble a good air compressor with a refrigerator compressor, then the vacuum sealer will turn out to be quite weak and low-vacuum. Such compressors cannot produce a vacuum of more than 104 Pa, i.e. They are not suitable for vacuumizing split systems.

Conclusions and useful video on the topic

The procedure for evacuating the freon circuit of a split system:

Review of different types of vacuum pumps, their capabilities and applications:

Comparison of the efficiency of a vacuum pump from a compressor from a refrigerator with a two-stage compressor:

When installing a split system, it is impossible to do without vacuuming the circuit, since such an air conditioner will not provide reliable long-term operation.

However, it is not profitable to specifically purchase a vacuum pump with a pressure gauge station, even for the installation of two or three home split systems. It is more rational to rent these devices. Or still call the experts, after making sure that they have the necessary equipment.

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