Once again about the repair of air conditioners

The situation when it is required to replace a failed air conditioner compressor, in most cases, is associated with neglect of the rules for installation and operation of the air conditioner.

Very often, the service department even detects darkening of the thermal insulation, air conditioner oil, or refrigerant leakage, at best, installing a filter on the liquid line or eliminating the leak and refilling the air conditioner, while radical measures are needed to save the compressor, which cannot be carried out at the installation site air conditioner. The result of this attitude is always the same – compressor failure. I would like to share the experience of repairing air conditioners in such situations when the air conditioner compressor can still be saved.

The need to repair the compressor – condensing unit of the air conditioner in the workshop arises not only in an emergency, for example, in case of a compressor failure, but also according to the results of a preventive inspection of the air conditioner.

Such situations can arise in the following cases:

1. According to the results of express analysis of compressor oil.
2. In case of loss of tightness of the freon circuit of the air conditioner.
3. If moisture gets into the freon circuit of the air conditioner.

In these cases, even if the air conditioning compressor is still running, its days are numbered. Urgent resuscitation will help extend the life of the air conditioner.

Express oil analysis.

These beautiful words hide quite simple actions:

1. It is necessary to obtain a sample (take a sample) of the refrigerating oil from the freon circuit.
2. Compare its color and smell with a good oil sample available.
3.Using an existing acid test, test the oil for acid.

How to take an oil sample for analysis?

It is known that oil circulates together with the refrigerant in the freon circuit of an air conditioner. When the air conditioner stops, the oil on the walls of the pipeline flows down through them. This oil can be sampled through the service port of the air conditioner.

For this you will need:

1. Ball valve with 1/4 “push-down.
2. A short hose with a 1/4 “fitting (a hose from a gauge manifold is fine).
3. Container for collecting oil.
4. Clean laboratory tube.

The procedure is as follows:

1. Stop the air conditioner, let the oil drain along the walls of the pipeline for 10-15 minutes.
2. Connect the ball valve to the service port.
3. Connect the hose to the ball valve. Place the free end of the hose in a container to collect the oil.
4. Open the tap. Gas escaping from the hose will carry the oil out. It remains only to collect it in a container. A little training, a few extra oil stains on your workwear and already taking an oil sample is not a problem for you.
5. Let the oil settle (because the oil contains dissolved refrigerant, it foams).
6. Empty the sample into a test tube.

The next step of the express analysis is to compare the oil sample with the existing sample in terms of color and smell. For this, the same amount of oil from the sample and the reference oil is placed in two identical test tubes and compared with each other..

  • a dark oil color and a burning smell indicates that the A / C compressor has overheated. The reason for overheating could be a refrigerant leak from the air conditioner or the operation of the air conditioner in the Heat mode at low negative temperatures. In this case, the oil loses its lubricating properties. As a result of the decomposition of oil on the walls of pipelines and internal parts of the air conditioner, resinous substances can be deposited, which can subsequently cause the failure of the air conditioner compressor.
  • a greenish tint of the oil indicates the presence of copper salts. The root cause is moisture in the circuit. The acidity test of such an oil is usually also positive. A clear oil with a slight odor, not much different in color from the sample, indicates that the conditioner does not need resuscitation.
  • And finally, an acid test will either completely dispel our concerns if the sample differs little from the sample, or confirm the need for emergency intervention..

    If it turns out that the oil is good and the air conditioner compressor is working normally, you need to return the sampled oil to the air conditioner.

    The sequence of actions is as follows:

    1. It is necessary to find suitable dishes. A transparent tall glass with a diameter of 3-4 cm is best suited.
    2. Connect a ball valve with a hose to the service port, in the same way as when taking an oil sample.
    3. Lower the free end of the hose into the glass.
    4. Pour enough oil into the glass so that it covers the hose connection..
    5. Mark the oil level on the glass.
    6. Briefly open the ball valve so that freon displaces air from the hose.
    7. Add the same amount of oil to the glass as was taken for the sample.
    8. Turn on the air conditioner for Cold.
    9. Close the liquid port of the air conditioner.
    10. When the pressure in the suction line becomes below atmospheric, open the valve and oil will flow through the service port into the air conditioner..
    11. Close the cock when the oil level reaches the mark.
    12. Turn off the air conditioner.
    13. Open the liquid port of the air conditioner.

    Loss of tightness of the freon circuit can be caused by various reasons and does not always lead to catastrophic results. Here the location of the leak, the amount of refrigerant that managed to leak, the time interval between the occurrence and detection of the leak, the operating mode of the air conditioner and other factors matter..

    What is the danger of a refrigerant leak?

    1. The compressor of the air conditioner, cooled by the refrigerant, as a result of the decrease in the density of the latter, overheats.
    2. Compressor discharge temperature rises, hot gas may damage the four-way valve.
    3. The compressor lubrication system is disturbed, the oil is carried away to the condenser.
    4. Air containing moisture can enter the air conditioner through the opening..

    Signs associated with the leak:

    1. Darkening of the compressor insulation.
    2. Periodic activation of the compressor thermal protection.
    3. Burnout of insulation on the discharge pipeline.
    4. Oil of dark color with a burning smell.
    5. Often a positive oil acid test.

    If the leak is detected on time, the refrigerant has not completely left, the air conditioner did not work for a long time without refrigerant, there are no accompanying symptoms – repair of the air conditioner in the workshop is not necessary.

    The share of sudden, catastrophic leaks caused by the destruction of pipelines is very small, leaks more often occur through small leaks on rolling joints and if you constantly monitor the operation of the air conditioner, leaks can be detected in a timely manner.

    What you should pay attention to:

    1. Not more than 5 minutes after turning on the air conditioner, depending on the selected mode, it should provide cold or warm air. If this does not happen, immediately turn off the air conditioner and call a repairman.
    2. If the pipes on the outdoor unit are covered with frost during operation of the air conditioner, a leak occurs, a master is needed.

    Following these simple rules will avoid high costs for air conditioner repairs..
    The ingress of moisture into the freon circuit most often occurs when the rules for installing the air conditioner are violated. One of the installation stages – the evacuation of the frenovy line, aims not only to make life difficult for the installer, but also to remove air and water vapor from the installed line. Such surrogates of this procedure, such as blowing the installed line with a refrigerant, cannot remove moisture at all, but only turns it into ice on the walls of copper pipes, which then melts, turns into water and does its dirty work.

    Acid oil test


    acid free


    with acid

    The danger of moisture getting inside the air conditioner is that it often does not manifest itself in any way up to the failure of the air conditioner compressor. The fact is that all processes in an air conditioner operating in cold mode occur at positive temperatures, and water manifests itself only when it freezes, causing a malfunction of the capillary tube or thermostatic valve.

    However, by indirect signs, the presence of moisture in the air conditioner can be determined:

  • One of the signs of the presence of moisture in the freon circuit has already been discussed; this is a greenish tint of the oil and a positive acidity test. It should be noted that this is already a pre-infarction condition of the air conditioner and urgent intervention is required.
  • In the earlier stages, moisture manifests itself at negative evaporation temperatures, for example, when the air conditioner is operating on heat at low outdoor temperatures or when refrigerant leaks. This turns the moisture into ice and clogs the capillary tube or nozzle of the expansion valve. As a result, the suction pressure of the air conditioner drops, the compressor temperature rises, and the thermal protection is activated. This cycle repeats until the compressor burns out..
  • Removing moisture from the freon circuit can also only be done in a workshop..

    What checks and how often need to be done in order to detect air conditioner disease in time?

    1. Checking the operation of the air conditioner each time it is turned on. It was mentioned above. Approximately 5 minutes after switching on, check whether the air conditioner is producing cold or warm (depending on the mode). If it is possible to see the taps of the outdoor unit, see if there is frost on them. If the results are negative, turn off the air conditioner and call the master.

    2. An oil sample is required in the following cases:

  • For air conditioners accepted for service, during the audit of the technical condition of the air conditioner.
  • For equipment that worked in winter but was not serviced.
  • When calling for repair of an air conditioner not being serviced.
  • When a refrigerant leak is detected from the air conditioner.
  • In any other suspicious situations.
  • Oil is the blood of a compressor and can tell a lot about the diseases of an air conditioner for an inquisitive master. What is the very procedure for reanimating the air conditioner in the workshop and is it really necessary? It is known, for example, that there are various methods for cleaning the freon circuit of the air conditioner, based on the use of filters that are installed in the break of the freon circuit and collect harmful substances.

    Why can’t such methods be used? Why do you need to do this work necessarily in the workshop?

    The fact is that in the situations described above, first of all, the compressor oil is contaminated or its properties change. Techniques based on the use of filters are, unfortunately, ineffective. There are no filters that can restore the lubricating properties of oil subjected to thermal decomposition; removal of moisture that is in the compressor under the oil layer using filters is also extremely ineffective. Therefore, the only way to clean the compressor oil is to replace it. This procedure can only be carried out after dismantling the compressor and is therefore only possible in a well equipped workshop..

    In this case, the following activities are carried out:

    1. Evacuation of refrigerant, dismantling of the compressor.
    2. Freeing the compressor from oil, flushing the compressor.
    3. Evacuation of the compressor.
    4. Compressor oil filling, compressor test.
    5. Flushing the input circuit of the condensing unit.
    6. Removal of the dryer filter, installation of the process filter.
    7. Installation of the compressor into the condensing unit.
    8. Installation of the condensing unit on the stand.
    9. Charging with refrigerant.
    10. Washing the compressor-condenser sump at the stand.
    11. Evacuation of freon.
    12. Replacing the technological filter of the dryer with a working one.
    13. Evacuation of the condensing unit.
    14. Charging with refrigerant, test run of the repaired unit.

    Since the contaminated oil is distributed throughout all elements of the air conditioner, part of the cleaning of the freon circuit has to be carried out at the installation site of the air conditioner. The purpose of these measures is to prevent dirty oil from entering the repaired unit..

    These include:

    1. Purging the freon lines and the evaporator with dry nitrogen.
    2. Installation of a process filter in the freon line.
    3. Vacuuming the freon line and evaporator.
    4. Starting the air conditioner in order to collect dirt on the filter.
    5. Condensation of refrigerant into the condensing unit.
    6. Removing the process filter.
    7. Vacuuming of the freon line.
    8. Starting up the air conditioner (test run).

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