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Air Conditioning
Controlling the climate inside your car
If your A/C system is not cooling properly, there could be a number of reasons for this. South Star Chrysler is equipped to check for leaks and repair A/C systems found in most vehicles.
Your air conditioning system has components that require internal lubrication (provided by periodic A/C system operation) to avoid drying out and cracking, which can lead to system leaks. Running your air conditioner regularly - even during winter months - helps lubricate these components and is recommended for many vehicles. Many systems run the air conditioning compressor during the defrost mode.
Automatic Temperature Control - With many Automatic Temperature Control (ATC) systems you don't even have to turn the A/C on. It automatically comes on as soon as the engine is started. You just select a temperature setting and the ATC system does the rest. The basic idea behind these system is to control both passenger heating and cooling with a single temperature setting. The system then automatically chooses heating or cooling and blower speeds to maintain a fixed temperature that has been preset by the driver and/or passenger. The "dual zone" automatic temperature control systems that are found in many vehicles allow occupants of each front seat to choose their own comfort setting. So if one person is always hot and the other is always cold, both people can be comfortable.
Most of the newer automatic climate control systems use small electric motors (actuators) to operate the airflow doors. The controller keeps tabs on their position by running the motors full open and full closed, then counting the revolutions of the motor armature to figure their exact position. Needless to say, these are complex, sophisticated temperature control systems.
Troubleshooting ATC systems has become a daunting task that requires specialized training and may require the use of a scan tool, DVOM or other diagnostic tools to pinpoint the cause. Some of the systems have self-diagnostic capabilities and can generate fault codes that indicate the nature of the problem. But in most cases, the technician still has to check out various components by measuring voltages, resistance, looking for opens or shorts in the wiring, etc. Once the problem has been diagnosed, the defective part can be replaced. What kind of parts are we talking about? Switches, sensors, relays, resistors, vacuum valves, vacuum motors, electric motors, blower motors, wiring harness repair kits or even controllers. As you can this is no longer a job for your average independent mechanic, but is better suited for the factory trained professionals at South Star Chrysler.
How it Works
Your automobile's air conditioning (A/C) system is divided into two sides, known as the high side and the low side. The compressor, beginning at the high side, functions likes a pump, moving refrigerant through the system. The expansion valve, which begins at the low side, restricts refrigerant flow, lowering the pressure and the temperature of the refrigerant.
Basic Automobile Air Condition Functions
The primary steps to an air conditioning system are: Compress, heat, cool, condense, dry, expand and cool, evaporate.
Compressor - The compressor's primary function is to compress and pressurize gaseous refrigerant. It takes in cool gas into its suction port and pressurizes it at its discharge port. A drive belt from the engine powers the compressor. The compressor has an electrically operated engagement clutch to either turn the refrigeration operation off or on.
Condenser - The condenser is located in front of the radiator (and kind of looks like a radiator too). Through the use of cool air flow provided by the engine fan, the condenser cools the hot gas and converts it to liquid. The liquid is still under considerable pressure and is warm, but not as hot or as high pressure as when it exited the compressor.
Receiver/Drier - The exiting liquid is sent via a small tube (liquid line) to a receiver/drier. The drier is a can with a desiccant bag inside. It looks about the size of a soda can, and is usually located very near the condenser outlet pipe. There is no pressure/temperature change at the receiver/drier, but moisture is removed by desiccant.
Expansion valve/Orifice Tube - As the high pressure, warm liquid exits the drier; it passes through an expansion device. It can either be an expansion valve (which modulates refrigerant flow in an expansion valve/drier system), or a fixed expansion orifice tube in a cycling clutch/orifice tube system (which expands at the same rate all the time). The two systems have slight functional differences, mainly in how the low temperature is maintained. For illustration, the pressurized liquid passes through the expansion device, the pressure is reduced considerably; hence the temperature drops also.
Cycling Clutch - The exiting liquid is sent via a small liquid line directly to an expansion orifice tube. The orifice tube is fixed, therefore the proportional pressure drop across it will constant. This type of expansion device must work in conjunction with a clutch cycling switch. Because the pressure drop across the orifice tube is constant, the switch is used to maintain the system low-pressure side in a certain operating range. The cycling clutch switch, through various pressure changes in the system, turns the compressor off and on during normal operation. A typical operation would have the switch turn the compressor on at about 45 psi and off at 25 degrees. This would maintain the evaporator refrigerant at temperatures around 35-45 degrees F.
Evaporator - As the cold liquid exits the expansion device, it is fed to a heat exchanger type device under the dash that blows warm air from the car interior across it. The cold liquid refrigerant is what cools the air you feel coming out of the ducts. As the air is cooled in the heat exchanger, the liquid refrigerant is heated in the other side of the heat exchanger and then it evaporates.
Accumulator - Only used in orifice tube system. It contains a desiccant bag also. The accumulator provides a similar function as the drier in the expansion valve system, but is located in the evaporator outlet instead. This positioning allows the accumulator to collect any un-evaporated refrigerant that may still be in the liquid state, hence protecting the compressor from liquid lock damage.
Refrigerant Leak Detectors - Fluorescent leak detection dyes are most popular because they're easy and inexpensive to use. All you need is a bottle of dye (a single dose is typically 1/4 oz.) or refrigerant that has already had dye added to it. The dye may be premixed with the refrigerant, or it can be injected into the system through the low-side service port with a special injector tool.
To find the leak, a UV lamp is used to scan all the places where leaks typically occur: the A/C compressor shaft seal, all hose and pipe connections, and the condenser. To enhance visibility, yellow-tinted goggles may also be worn to increase the color contrast between the dye and background.
Electronic Leak Detectors - Heated diode detectors use a heated ceramic diode that generates an electrical current when it comes into contact with halogen gas. This technology is more sensitive and can often detect leaks as small as 0.1 oz. per year, and it is less apt to give false alarms.
If your A/C system is not cooling properly, there could be a number of reasons for this. South Star Chrysler is equipped to check for leaks and repair A/C systems found in most vehicles.
Your air conditioning system has components that require internal lubrication (provided by periodic A/C system operation) to avoid drying out and cracking, which can lead to system leaks. Running your air conditioner regularly - even during winter months - helps lubricate these components and is recommended for many vehicles. Many systems run the air conditioning compressor during the defrost mode.
Automatic Temperature Control - With many Automatic Temperature Control (ATC) systems you don't even have to turn the A/C on. It automatically comes on as soon as the engine is started. You just select a temperature setting and the ATC system does the rest. The basic idea behind these system is to control both passenger heating and cooling with a single temperature setting. The system then automatically chooses heating or cooling and blower speeds to maintain a fixed temperature that has been preset by the driver and/or passenger. The "dual zone" automatic temperature control systems that are found in many vehicles allow occupants of each front seat to choose their own comfort setting. So if one person is always hot and the other is always cold, both people can be comfortable.
Most of the newer automatic climate control systems use small electric motors (actuators) to operate the airflow doors. The controller keeps tabs on their position by running the motors full open and full closed, then counting the revolutions of the motor armature to figure their exact position. Needless to say, these are complex, sophisticated temperature control systems.
Troubleshooting ATC systems has become a daunting task that requires specialized training and may require the use of a scan tool, DVOM or other diagnostic tools to pinpoint the cause. Some of the systems have self-diagnostic capabilities and can generate fault codes that indicate the nature of the problem. But in most cases, the technician still has to check out various components by measuring voltages, resistance, looking for opens or shorts in the wiring, etc. Once the problem has been diagnosed, the defective part can be replaced. What kind of parts are we talking about? Switches, sensors, relays, resistors, vacuum valves, vacuum motors, electric motors, blower motors, wiring harness repair kits or even controllers. As you can this is no longer a job for your average independent mechanic, but is better suited for the factory trained professionals at South Star Chrysler.
How it Works
Your automobile's air conditioning (A/C) system is divided into two sides, known as the high side and the low side. The compressor, beginning at the high side, functions likes a pump, moving refrigerant through the system. The expansion valve, which begins at the low side, restricts refrigerant flow, lowering the pressure and the temperature of the refrigerant.
Basic Automobile Air Condition Functions
The primary steps to an air conditioning system are: Compress, heat, cool, condense, dry, expand and cool, evaporate.
Compressor - The compressor's primary function is to compress and pressurize gaseous refrigerant. It takes in cool gas into its suction port and pressurizes it at its discharge port. A drive belt from the engine powers the compressor. The compressor has an electrically operated engagement clutch to either turn the refrigeration operation off or on.
Condenser - The condenser is located in front of the radiator (and kind of looks like a radiator too). Through the use of cool air flow provided by the engine fan, the condenser cools the hot gas and converts it to liquid. The liquid is still under considerable pressure and is warm, but not as hot or as high pressure as when it exited the compressor.
Receiver/Drier - The exiting liquid is sent via a small tube (liquid line) to a receiver/drier. The drier is a can with a desiccant bag inside. It looks about the size of a soda can, and is usually located very near the condenser outlet pipe. There is no pressure/temperature change at the receiver/drier, but moisture is removed by desiccant.
Expansion valve/Orifice Tube - As the high pressure, warm liquid exits the drier; it passes through an expansion device. It can either be an expansion valve (which modulates refrigerant flow in an expansion valve/drier system), or a fixed expansion orifice tube in a cycling clutch/orifice tube system (which expands at the same rate all the time). The two systems have slight functional differences, mainly in how the low temperature is maintained. For illustration, the pressurized liquid passes through the expansion device, the pressure is reduced considerably; hence the temperature drops also.
Cycling Clutch - The exiting liquid is sent via a small liquid line directly to an expansion orifice tube. The orifice tube is fixed, therefore the proportional pressure drop across it will constant. This type of expansion device must work in conjunction with a clutch cycling switch. Because the pressure drop across the orifice tube is constant, the switch is used to maintain the system low-pressure side in a certain operating range. The cycling clutch switch, through various pressure changes in the system, turns the compressor off and on during normal operation. A typical operation would have the switch turn the compressor on at about 45 psi and off at 25 degrees. This would maintain the evaporator refrigerant at temperatures around 35-45 degrees F.
Evaporator - As the cold liquid exits the expansion device, it is fed to a heat exchanger type device under the dash that blows warm air from the car interior across it. The cold liquid refrigerant is what cools the air you feel coming out of the ducts. As the air is cooled in the heat exchanger, the liquid refrigerant is heated in the other side of the heat exchanger and then it evaporates.
Accumulator - Only used in orifice tube system. It contains a desiccant bag also. The accumulator provides a similar function as the drier in the expansion valve system, but is located in the evaporator outlet instead. This positioning allows the accumulator to collect any un-evaporated refrigerant that may still be in the liquid state, hence protecting the compressor from liquid lock damage.
Refrigerant Leak Detectors - Fluorescent leak detection dyes are most popular because they're easy and inexpensive to use. All you need is a bottle of dye (a single dose is typically 1/4 oz.) or refrigerant that has already had dye added to it. The dye may be premixed with the refrigerant, or it can be injected into the system through the low-side service port with a special injector tool.
To find the leak, a UV lamp is used to scan all the places where leaks typically occur: the A/C compressor shaft seal, all hose and pipe connections, and the condenser. To enhance visibility, yellow-tinted goggles may also be worn to increase the color contrast between the dye and background.
Electronic Leak Detectors - Heated diode detectors use a heated ceramic diode that generates an electrical current when it comes into contact with halogen gas. This technology is more sensitive and can often detect leaks as small as 0.1 oz. per year, and it is less apt to give false alarms.