How to check the high pressure sensor G65 of the air conditioning system
Content
The introduction of high-tech technologies in the automotive industry makes it possible to improve all kinds of systems, significantly increasing their efficiency and performance. But, one way or another, any, even the most reliable and high-tech auto assembly can be subject to all sorts of failures and malfunctions, which are not always possible to identify.
To successfully solve such problems on your own, you need to systematically replenish your baggage of skills and abilities, paying attention to the key principles of operation of various components and devices.
In this article, we will talk about problems in the climate control system of a car. In this case, we will consider one of the common problems within the framework of a given topic: malfunctions of the G65 sensor.
The role of the high pressure sensor in the air conditioning system
The presented system is distinguished by the presence of a wide variety of components that allow for an uninterrupted supply of cooled air to the interior of the car. One of the key elements of the climate control system is a sensor marked G65.
It is intended primarily to protect the system from breakdowns caused by overpressure. The fact is that the presented system is maintained in working condition in the presence of an average operating value in the high-pressure circuit, depending on the temperature regime. So, at a temperature of 15-17 0C, the optimal pressure will be about 10-13 kg / cm2.
From the course of physics it is known that the temperature of a gas is directly dependent on its pressure. In a particular case, the refrigerant, for example, freon, acts as a gas. As the temperature rises, the pressure in the climate control system begins to rise, which is undesirable. At this point, the DVD begins to work. If you look at the diagram of the car's air conditioning system, it becomes clear that this sensor is tied to the fan, sending a signal at the right time to turn it off.
The circulation and maintenance of the operating pressure of the refrigerant in the system under consideration is carried out thanks to the compressor, on which an electromagnetic clutch is installed. This drive device provides the transmission of torque to the compressor shaft from the car engine, through a belt drive.
The operation of the electromagnetic clutch is the result of the action of the sensor in question. If the pressure in the system has exceeded the allowable parameter, the sensor sends a signal to the compressor clutch and the latter stops working.
Among other things, if a malfunction occurs in the operation of one or another system node, a situation may arise when in the high pressure circuit, this operating indicator will begin to approach the emergency value, which can lead to serious consequences.
As soon as such circumstances arise, the same DVD starts working.
The device and principle of operation of the sensor G65
What is this simple device? Let's get to know him better.
As in any other sensor of this kind, the G65 implements the principle of converting mechanical energy into an electrical signal. The design of this micromechanical device includes a membrane. It is one of the key working elements of the sensor.
The degree of deflection of the membrane, depending on the pressure exerted on it, is taken into account when generating the output pulse sent to the central control unit. The control unit reads and analyzes the incoming pulse in accordance with the inherent characteristics, and makes changes to the operation of the system nodes by means of an electrical signal. The presented nodes of the system, in this case, include the electric clutch of the air conditioner and the electric fan.
It should also be noted that modern DVDs often use a silicon crystal instead of a membrane. Silicon, due to its electrochemical properties, has one interesting feature: under the influence of pressure, this mineral is able to change the electrical resistance. Acting on the principle of a rheostat, this crystal, built into the sensor board, allows you to send the necessary signal to the recording device of the control unit.
Let us consider the situation when the DVD is triggered, provided that all the nodes of the presented system are in good order and operate in the normal mode.
As already specified above, this sensor is located in the high pressure circuit of the system. If we draw an analogy with any closed system of this kind, we can say that it is mounted on the "supply" of the refrigerant. The latter is injected into the high pressure circuit and, passing through a narrow line, is gradually compressed. Freon pressure rises.
In this case, the laws of thermodynamics begin to manifest themselves. Due to the high density of the refrigerant, its temperature begins to rise. To get rid of this phenomenon, a condenser is installed, outwardly similar to a cooling radiator. It, under certain operating modes of the system, is forcibly blown by an electric fan.
So, when the air conditioner is turned off, the refrigerant pressure in both circuits of the system is equalized and is about 6-7 atmospheres. As soon as the air conditioner turns on, the compressor comes into operation. By pumping freon into the high pressure circuit, its value reaches the working 10-12 bar. This indicator is steadily growing, and excess pressure begins to act on the spring of the HPD membrane, closing the control contacts of the sensor.
The pulse from the sensor enters the control unit, which sends a signal to the condenser cooling fan and the compressor drive electric clutch. Thus, the compressor is disengaged from the engine, stopping pumping refrigerant into the high pressure circuit, and the fan stops working. The presence of a high pressure sensor allows you to maintain the operating parameters of the gas and stabilize the operation of the entire closed system as a whole.
How to check the air conditioning sensor for a malfunction
Often, owners of cars equipped with the presented system are faced with the fact that at one point, the air conditioner simply stops working. Often, the cause of such a malfunction lies in the breakdown of the DVD. Consider some of the most common cases of DVD failure and how to detect it.
At the initial stage of checking the performance of the specified sensor, it should be visually inspected. It is necessary to make sure that there is no damage or contamination on its surface. In addition, you should pay attention to the wiring of the sensor and make sure that it is in good condition.
If a visual inspection did not reveal the causes of failures in its operation, a more detailed diagnosis should be resorted to using an ohmmeter.
The sequence of actions in this case will look like this:
- Remove underwater wires from DVD;
- Connect the ohmmeter clamps to the sensor terminals, while the set resistance range should be at least 100 kOhm;
- Measure the resistance of the sensor with a tester.
According to the results of the measurements, we can conclude that the DVD is in good condition.
So, the sensor is operational provided that:
- In the presence of excess pressure in the line, the ohmmeter must register a resistance of at least 100 kOhm;
- If there is insufficient pressure in the system, the multimeter readings should not exceed the 10 ohm mark.
In all other cases, we can assume that the DVD has lost its performance. If, according to the results of the test, it turned out that the sensor is working, you should check the sensor for "short circuit". To do this, you need to throw one terminal on one of the outputs of the DVD, and touch the second to the "mass" of the car.
If there is insufficient pressure in the presented system, the working sensor will give out at least 100 kOhm. Otherwise, it can be concluded that the sensor is out of order.
Replacement Instructions
If, as a result of the above diagnostic measures, it was possible to find out that the sensor ordered a long life, it is necessary to replace it promptly.
It is worth noting that for this it is not at all necessary to contact specialized services and car repair shops. This procedure can be successfully performed in normal garage conditions.
The replacement algorithm consists of the following steps:
- Dismantling of body elements that prevent access to the sensor;
- Shutdown of underwater conclusions of the sensor;
- Removing the sensor with the car off;
- Connection of underwater conclusions;
- Installation of body elements.
By itself, replacing the sensor should not cause difficulties, but it is still necessary to adhere to some guidelines of a recommendatory nature.
First, when buying a new non-original sensor, you need to make sure that it meets the specified parameters. In addition, it happens that a new DVD is not always equipped with a sealing collar. Therefore, in this case, it is necessary to take care of its acquisition, since there is a possibility that the old sealant has simply become unusable.
It often happens that when replacing the DVD, the air conditioning system restores its performance only partially. In this case, with a high degree of probability it can be argued that the level of refrigerant in the system is low. To solve this problem, you will need to refuel the system in a specialized car service.
