AC compressor packing replacement with your own hands

How to properly check operation of compressor

It is better to entrust the work of automobile conditioner to professionals, while self-diagnostics is worth to pay attention to the presence of strange sounds and smells.

As to more deep diagnostics it is carried out in the following order:

  • First of all it is necessary to check how the temperature in the salon changes during work in normal mode, so sometimes it is possible to reveal obvious defects in the controls.
  • Another quite effective way is a banal visual inspection. You should pay attention not only to the compressor, but also to all the other parts of the system, in particular, pipes, hoses, radiators, etc. д.
  • A very important point is to measure the pressure inside the air conditioning system, and check it as in the disconnected and working condition.


Self-repair of the air conditioning compressor can also be performed to repair the electromagnetic clutch. Inspection of this part includes checking the presence of grease on the rotor and on the pressure plate. Clutch bearing should be free of grease leakage. Use a coil resistance test tool to determine the resistance of the coil. Coil resistance should be in the range of 3.15 to 3.45 at 20°C (122°F to 113°F). In case of abnormality it must be replaced with new part. The last action will be to measure the gap between the pulley and the clutch disc. If there is abnormality, the magnetic field will not be able to push the clutch to the pulley. Range should be between 0.35-0.65 mm.

How to check the air conditioner compressor?

compressor, packing, replacement, your, hands

Air conditioner compressor looks like this

How to check the compressor in the air conditioner? The most common type of compressor are single-phase compressors that have a starting winding.

To get access to the pins you should disassemble the air conditioner. It is important to have access to the compressor after taking it apart. The contacts most often have a protection in the form of a cover. The lid is screwed on. To find the cover you can by the wires to the compressor. After you remove the cover, you can see the 3 contact pins. On the three pins there are terminals with wires.

You should first remove the wires and then measure the resistance between the pins. The measurement can be made with a multimeter. The multimeter should be switched to a function that allows you to measure the resistance. This function is marked with the symbol Ω on the instrument. If this unit reads infinitely high resistance between the C terminals and the others, it means a breakage. In the situation of built-in protection it is important to be sure that the compressor is not overheated. If the protection is external, the compressor is defective. If the resistance is nearly zero, it is an indication of a short circuit and a faulty element.

Depending on the capacity of this element of the air conditioner, the resistance value varies. The value must be between 1 and 20 ohms.

Each compressor has thermal protection, which can be built in or external.

If the thermal protection is external, it can be checked separately and replaced if it is defective. It should be normally short-circuited. Opening occurs only when a certain temperature is reached (100-120°C).

First, the pressure in the system can be out of line, which will lead to a breakdown.

Secondly, the compressor shaft bearings can wear out or overheat (depending on the period of use).

Thirdly, the bearings of the pulley and the compressor shaft can overheat and wear out.

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And fourth, there is a probability of breach of tightness, because of wear and tear.

Repair and replacement of the shaft compressor oil seal requires great accuracy and experience of the master. The following paragraphs describe the process of replacing the oil seal on the example of the Honda Accord with engine 2.4 liters.

  • First you need to disassemble the compressor. Don’t forget to prepare consumables, spares and tools. The compressor is washed of dirt, and is dried.
  • It is necessary to unscrew the main nut M14 (located in the center of the shaft), remove the plate (pressure plate), the pulley and the electromagnetic coil. For the last two, you need a circlip puller. Then put the pulley back on.
  • Let’s remove fastening of the front cover of the compressor, remove it. Here you can see the corrosion which caused the failure.
  • Work the shaft with a fine sandpaper until the corrosion is removed. (Important! There should be no scratches, and the finer the pattern is, the better the work and the longer the gland will last).
  • Remove the shaft bearing.
  • Then remove the circlip and oil seal. Both of these elements are usually quite worn out.
  • Further, when the front cover is removed, it is possible to see that shells are formed between it and the case of the compressor. This is due to oxidation, which is in turn due to environmental influences and moisture.
  • The seating should be cleaned. At first in the usual way, then with sandpaper.
  • When all works with sweeping are finished, and all as in the first light, we proceed to assembling of the compressor. Here it is necessary to involve all your accuracy, press the shaft of the compressor on a front cover.
  • In the same way accurately, cover together with a shaft we mount on the case of the compressor, here it is very important to control constantly position of a shaft to prevent “boring” it on walls of an operating bearing inside of the compressor.
  • Next, screw the bolts fixing the front cover. And the compressor is assembled. It remains only to install a new packing on the shaft. The use of special devices is required.
  • After installation, do not neglect to check the tightness of the gland. This is done at a pressure of about eight atmospheres.
  • Install the new compressor shaft bearing, just as carefully.
  • Next, the assembly of the coil, as well as the pulley and the clamping plate. (If you find additional worn parts, it is necessary to replace or repair them).

After all the work is done, the necessary amount of oil needs to be poured in. Be guided by the amount of oil drained.

At this point, replacing the shaft seal was at its logical conclusion. We hope you find the information useful, and wish you good luck in your work.

Diagnose the device

It is necessary to disassemble and reassemble the unit in the case when the air conditioning system began to work with malfunctions. There may be many reasons why the air conditioner does not work, starting from the failure of electrical coupling and ending with the wear and tear of seals. Before disassembling the system, it is necessary to check the functionality of all its elements, so first with the signs of breakdown.


It should be noted that you can tell if a compressor mechanism is malfunctioning by simply inspecting the units.

What are the symptoms indicating that it does not work:

  • Weak air flow coming from the system air ducts, which can be detected without disassembling the unit. Start the engine and let it warm up to the working temperature, then turn on the air conditioning system at full power and check the efficiency of the unit. If the air flow is too weak, the cause may also be a leak of working fluid from the system.
  • Noise uncharacteristic of the air conditioner. One of the reasons in this case is precisely the compressor unit, but the noisiness during the operation of the air conditioner is not necessarily due to this reason.
  • A resounding knocking sound. Unlike noise, this knock is loud enough and any motorist will notice its occurrence. It is possible to learn about occurrence of a knock, when switching on the auto conditioner.
  • If you pay more attention you will notice that the system starts to activate in a different way than usual. For example, if there is usually a clicking sound after starting the air conditioner, it will now be absent.
  • Delayed activation of the compressor unit after activation of the air conditioning system.
  • Another sign. the oil in the conditioner has begun to have more green tint. This can tell you that moisture has entered the compressor assembly. In the event that you do not remove the moisture in time, it can lead to the fact that over time, it can become ice. Accordingly, the ice will block the capillary pipe, and as a result, the air conditioner will regularly overheat, and this, in turn, will lead to a breakdown of the compressor mechanism.
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What causes a compressor unit to break down

  • Wear of the oil seal. This element belongs to the category of consumables, so from time to time it should be replaced anyway. The oil seal failure is usually caused by CFC leakage from the unit. If mechanical problems occur in the mechanism, as a rule, either the stuffing box itself or the mating point is leaking. You can determine the leakage of the oil seal visually, with the help of an ultraviolet lamp, but for this you should add fluorescent paint in the unit in advance. If the stuffing box packing is worn out, it is necessary to purchase a repair kit and replace the part.
  • If the noise occurs while running the air conditioner, it can indicate the failure of bearing elements of the shaft or drive sheave. Besides, the noise can be caused by the necessity of belt tensioning. To diagnose such a malfunction is possible by turning the shaft of the compressor, with the clutch should be disconnected, and the belt is slightly loose. If the shaft rotates with difficulty, the bearing device is most likely to be the cause. If the shaft rotates without much effort, it is most likely the reason is the bearing element of the shaft.
  • One of the reasons of compressor mechanism failure is overheating of coil. If the compressor overheats regularly, the coil will over time begin to melt, leading to a breakdown of the unit.
  • If the cause of malfunction is the appearance of knocks, then most likely the problem is caused by bent valves or worn working surfaces of pistons. If this is the reason, you can try to replace the valves or pistons, but usually the cost of such repairs is quite high, so it may be more appropriate to replace the whole unit (the author of the video about replacement of the bearing device in the compressor SANDEN. vassilij pavliuk).

Why it can work badly?

There is an opinion among the Russian motorists that compressor of a car air conditioner is almost a prototype of the eternal engine and that is why it does not need servicing at all. We don’t like to read instructions and get seized only at the moment when it becomes necessary to change the whole cooling system. The compressor with time starts humming all of a sudden, and the design of the car air conditioner is such that it is not immediately clear where the hum comes from. Causes can vary, but the first thing that comes to mind is a faulty pulley bearing or worn belt drive. Such problems can be solved by the motorist himself, the replacement here will not cause difficulties, if there are skills to communicate with the “iron”.

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It can be much more serious if the piston inside the machine is jammed. There is hardly anything that can be done here, as for sure the broken part has damaged the valves and walls. If you are not lazy, replacement will wait, to try to make a repair of a compressor of an auto conditioner is not forbidden. But as practice shows, such measures result only in temporary improvements and in some period the breakage will repeat. Optimal variant for the automobile conditioner in such case. complete replacement of a compressor.

often than other breakdowns, there is a breach of airtightness. Happens either because of damage to the packing, or because of loosening of the mounting points of the main pipes to the device itself. In the case of the oil seal, the case is complicated, because you need to replace it. If you’ve never pressed it out, you’re better off not trying. Here you need an expert and availability of appropriate equipment. Looseness is not difficult to fix with your own hands.

Denso air conditioning compressor replacement of the press wheel bearing. Clutch replacement

When you need air conditioner repair?

The air conditioning system is needed not only to cool the air inside the car, but also to clean it from unnecessary moisture and odors. The main feature is that the device works from the car engine, not from electricity. The principle of operation is comparable with that of a simple refrigerator. The system is a sealed container that is filled with special oil. It is responsible for lubrication of compressor and piping. The system also contains freon, which is necessary for cooling.

If the car in a traffic jam overheats and consumes more fuel, there may be a problem with the air conditioning system condenser. Also in this case, oily spots should form on it. Another warning sign. overheating of the motor and the engine compartment as a whole, as well as slippage of the drive belt and electromagnetic clutch. Sometimes there are unpleasant smells and water droplets in the passenger compartment. All of these are signs that the evaporator is malfunctioning.

Excessive noise and insufficient efficiency of the system, as well as oily spots on the compressor indicate the necessity of its urgent inspection. You should be warned by frequent switching off of the compressor, frost penetration of evaporator tubes and filter, and also freezing of outgoing hoses.

How to properly check the compressor operation

To check the work of the car air conditioner, it is better to trust professionals, with self-diagnosis you should pay attention to the presence of strange sounds and smells.

As for more in-depth diagnostics, it is carried out in the following order:

  • First of all it is necessary to check the system when it works in standard mode, it is necessary to check how the temperature in the cabin changes when you change the settings, so sometimes you can identify obvious defects in the control.
  • Another quite effective way is a trivial visual inspection, and one should pay attention not only to the compressor, but also to all the other parts of the system, in particular, pipes, hoses, radiators, etc. д.
  • A very important point is to measure the pressure inside the air conditioning system, and it is necessary to check it both in disconnected and working condition.
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