Heating & Air Conditioning - Service Information: Overview Dodge Dakota III рестайлинг

DESCRIPTION

A Manual Temperature Control (MTC) single zone type heating-A/C system is standard equipment on this vehicle.

To maintain the performance level of the heating, ventilation and air conditioning (HVAC) system, the engine cooling system must be properly maintained. The use of a bug screen is not recommended. Any obstructions in front of the radiator or A/C condenser will reduce the performance of the A/C and engine cooling systems.

The engine cooling system includes the radiator, thermostat, radiator hoses and the engine coolant pump. See COOLING for more information before opening or attempting any service to the engine cooling system.

Scheme 6

All vehicles are equipped with a common HVAC housing (1). The heating-A/C system combines A/C, heating and ventilating capabilities in a single HVAC housing mounted within the passenger compartment behind the instrument panel. The HVAC housing includes

1. a heater core (2)
2. blend-air doors and actuator (3)
3. an A/C evaporator (4)
4. a blower motor resistor (5)
5. a recirculation-air door and actuator (6)
6. a blower motor (7)
7. an evaporator temperature sensor (8)
8. mode-air doors and actuators (9)

Based upon the mode selected, conditioned air can exit the HVAC housing through one or a combination of the three main housing outlets: defrost, panel or floor. The defrost and panel outlets are located on the top of the HVAC housing and the floor outlet is located on the bottom of the HVAC housing. Once the conditioned air exits the HVAC housing, it is further directed through molded plastic ducts to the outlets within the vehicle interior. These outlets and their locations are as follows

1. Defroster Outlet - A single large defroster outlet is located in the center of the instrument panel top cover, near the base of the windshield.
2. Side Window Demister Outlets - There are two side window demister outlets, one is located at each outboard end of the instrument panel face near the A-pillars.
3. Panel Outlets - There are four panel outlets in the instrument panel, one located near each outboard end of the instrument panel facing the rear of the vehicle and two located at the top of the instrument panel center bezel.
4. Floor Outlets - There are two floor outlets, one located above each side of the floor panel center tunnel near the dash panel.

OPERATION

The heating-A/C system used in this vehicle is a single zone, blend-air type system. In this blend-air heating-A/C system, two blend-air doors control the amount of conditioned air that is allowed to flow through, or around the heater core. The temperature control determines the discharge air temperature by operating the blend-air doors. This allows an almost immediate control of the output air temperature of the system.

Scheme 7

Note. Typical blend-air type HVAC system shown in illustration.

The heating-A/C system pulls outside (ambient) air through the fresh air intake (4) located at the cowl panel at the base of the windshield and into the air inlet housing above the heating, ventilation and air conditioning (HVAC) housing and through the A/C evaporator (7). Air flow is then directed either through or around the heater core (2). This is done by adjusting the position of the blend-air doors (3) with the temperature control located on the A/C-heater control in the instrument panel. Air flow is then directed out the floor outlet (8), instrument panel outlet (10) or the defroster outlet (1) in various combinations by adjusting the position of the mode-air doors (9 and 11) using the mode control located on the A/C-heater control. The temperature and mode control uses electrical actuators to operate the air doors.

The velocity of the air flow out of the outlets can be adjusted with the blower speed control located on the A/C-heater control.

The fresh air intake can be shut off by pressing the Recirculation button on the A/C-heater control. This will operate the electrically actuated recirculation-air door (5), which closes off the fresh air intake. With the fresh air intake closed, the conditioned air within the vehicle is pulled back into the HVAC housing through the recirculation air intake (6) located within the passenger compartment.

The A/C compressor can be engaged by pressing the A/C (snowflake) button on the A/C-heater control. It will automatically engage when the mode control is set in any Mix to Defrost position. This will remove heat and humidity from the air before it is directed through or around the heater core. The mode control on the A/C-heater control is used to direct the conditioned air to the selected system outlets.

The defroster outlet receives airflow from the HVAC housing through the molded plastic defroster duct, which connects to the HVAC housing defroster outlet. The airflow from the defroster outlet is directed by fixed vanes in the defroster outlet grille and cannot be adjusted. The defroster outlet grille is serviceable from the instrument panel.

The side window demister outlets receive airflow from the HVAC housing through the molded plastic demister ducts. The demisters direct air from the HVAC housing through the outlets located on the top corners of the instrument panel. The demisters operate when the mode control is positioned in the bi-level, floor, floor-defrost and defrost settings. The airflow from the side window demister outlets is directed by fixed vanes in the demister outlet grilles and cannot be adjusted. The demister outlet grilles are only serviced with the instrument panel outlets.

The instrument panel outlets receive airflow from the HVAC housing through a molded plastic center distribution duct, center panel duct and two end panel ducts. The two end panel ducts direct airflow to the left and right instrument panel outlets, while the center panel duct directs airflow to the two center panel outlets. Each of these outlets can be individually adjusted to direct the flow of air.

The floor outlets receive airflow from the HVAC housing through the floor distribution duct. The front floor outlets are integral to the molded plastic floor distribution duct, which is secured to the bottom of the HVAC housing. The floor outlets cannot be adjusted.

Note. It is important to keep the air intake opening clear of debris. Leaf particles and other debris that is small enough to pass through the cowl opening screen can accumulate within the HVAC housing. The closed, warm, damp and dark environment created within the housing is ideal for the growth of certain molds, mildews and other fungi. Any accumulation of decaying plant matter provides an additional food source for fungal spores, which enter the housing with the fresh intake-air. Excess debris, as well as objectionable odors created by decaying plant matter and growing fungi can be discharged into the passenger compartment during heater-A/C operation if the air intake opening is not kept clear of debris.

This A/C system uses an A/C orifice tube to meter the flow of refrigerant to the A/C evaporator. The A/C evaporator cools and dehumidifies the incoming air prior to blending it with the heated air. To maintain minimum evaporator temperatures and prevent evaporator freezing, an evaporator temperature sensor is used. The sensor is located downstream of the A/C evaporator and supplies an evaporator temperature signal to the A/C-heater control. The A/C-heater control broadcasts the A/C request on the controller area network (CAN) B bus, where it is read and processed by the front control module (FCM), which in turn broadcasts it on the CAN C bus, where it is read and processed by the powertrain control module (PCM) which cycles the A/C clutch relay as necessary.

The blend door actuator is connected to the Air Conditioning (A/C) heater control through the vehicle electrical system by a dedicated two-wire lead and connector of the HVAC wire harness. The blend door actuator can move the blend-air doors in two directions. When the A/C-heater control pulls the voltage on one side of the motor connection high and the other connection low, the blend-air doors will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the blend-air doors move in the opposite direction.

When the A/C-heater control makes the voltage to both connections high or low, the blend-air doors stop and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the blend door actuator and the blend-air doors. The A/C-heater control learns the blend-air doors stop positions during the calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the blend door actuator circuit.

The blend door actuator is diagnosed using a scan tool. Refer to DTC-Based Diagnostics/HVAC - Diagnosis and Testing .

The blend door actuator cannot be adjusted or repaired. The blend door actuator must be replaced if inoperative or damaged.

The two mode door actuators (1) are reversible, 12-volt direct current (DC), servo motors. The mode door actuators are located on the driver side of the HVAC housing. The mode door actuators are mechanically connected to the floor/defrost and the panel-air doors. The mode door actuators are interchangeable with the actuators for the blend-air doors and the recirculation-air door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle (2). Each actuator also has an identical output shaft with splines (3) that connects it to its respective door linkage and three integral mounting tabs (4) that allow the actuator to be secured to the HVAC housing. The mode door actuators do not require mechanical indexing to the mode-air doors, as they are electronically calibrated by the A/C-heater control.

The two mode door actuators can be serviced from underneath the drivers side of the instrument panel.

Both the floor/defrost actuator and the panel door actuator (mode door actuators) are connected to the A/C-heater control through the vehicle electrical system by dedicated two-wire leads and connectors of the HVAC wire harness. Each mode door actuator can move the floor/defrost or the panel-air doors in two directions. When the A/C-heater control pulls the voltage on one side of an actuator motor connection high and the other connection low, the respective mode-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the mode-air door moves in the opposite direction.

When the A/C-heater control makes the voltage to both connections high or both connections low, the respective mode-air door stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of both mode door actuators and the mode-air doors. The A/C-heater control learns the mode-air door stop positions during the calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the mode door actuator circuits.

The mode door actuators are diagnosed using a scan tool. Refer to DTC-Based Diagnostics/HVAC - Diagnosis and Testing .

The mode door actuators cannot be adjusted or repaired and must be replaced if inoperative or damaged.

The recirculation door actuator (1) is a reversible, 12 volt direct current (DC), servo motor. The recirculation door actuator is located on the left side of the HVAC air inlet housing. The recirculation door actuator is interchangeable with the actuators for the blend-air doors and the mode-air doors. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle (2). Each actuator also has an identical output shaft with splines (3) that connects it to its door linkage and three integral mounting tabs (4) that allow the actuator to be secured to the air inlet housing. The recirculation door actuator does not require mechanical indexing to the recirculation-air door, as it is electronically calibrated by the A/C-heater control.

The recirculation door actuator can be accessed for serviced by removing the air inlet housing.

The recirculation door actuator is connected to the A/C-heater control through the vehicle electrical system by a dedicated two-wire lead and connector of the HVAC wire harness. The recirculation door actuator can move the recirculation-air door in two directions. When the A/C-heater control pulls the voltage on one side of the motor connection high and the other connection low, the recirculation-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the recirculation-air door moves in the opposite direction.

When the A/C-heater control makes the voltage to both connections high or both connections low, the recirculation-air door stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the recirculation door actuator and the recirculation-air door. The A/C-heater control learns the recirculation-air door stop positions during the calibration procedure and will store a diagnostic trouble code (DTC) for any problems it detects in the recirculation door actuator circuits.

The recirculation door actuator is diagnosed using a scan tool. Refer to DTC-Based Diagnostics/HVAC - Diagnosis and Testing .

The recirculation door actuator cannot be adjusted or repaired and must be replaced if inoperative or damaged.

The A/C clutch relay is an electromechanical switch that uses a low current input controlled by the powertrain control module (PCM) to control the high current output to the A/C clutch field coil. The movable, common feed relay contact is held against the fixed, normally closed relay contact by spring pressure. When the electromagnetic relay coil is energized, it draws the movable common feed relay contact away from the fixed, normally closed relay contact and, holds it against the fixed, normally open relay contact. This action allows high current to flow to the A/C clutch field coil.

When the relay coil is de-energized, spring pressure returns the movable relay contact back against the fixed, normally closed contact point. The resistor or diode is connected in parallel with the relay coil, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil collapses.

The A/C clutch relay terminals are connected to the vehicle electrical system through a receptacle in the integrated power module (IPM). The inputs and outputs of the A/C clutch relay include

1. The common feed terminal (30) receives fused battery current through a B(+) circuit at all times.
2. The coil ground terminal (85) receives a ground input from the PCM through the A/C clutch control circuit only when the PCM electronically pulls the control circuit to ground.
3. The coil battery terminal (86) receives fused battery current through the ignition switch circuit only when the switch is in RUN.
4. The normally open terminal (87) provides a battery current output to the A/C clutch coil through the A/C clutch relay output circuit only when the compressor clutch relay coil is energized.
5. The normally closed terminal (87A) is not connected to any circuit in this application, but provides a battery current output only when the A/C clutch relay coil is de-energized.

The A/C clutch relay cannot be repaired must be replaced if found in operative or damaged. See SYSTEM WIRING DIAGRAMS for diagnosis and testing of the ISO-standard relay and for complete HVAC wiring diagrams.

Scheme 8

1. Disconnect and isolate the negative battery cable.
2. Open the cover of the integrated power module (IPM) (1) located in the engine compartment. NOTE: Refer to the fuse and relay layout map on the IPM cover for A/C clutch relay identification and location.
3. Remove the A/C clutch relay (2) from the IPM.

The blower motor relay is an electromechanical switch that uses a low current input from the battery to control the high current output to the blower motor. The movable, common feed relay contact is held against the fixed, normally closed relay contact by spring pressure. When the electromagnetic relay coil is energized, it draws the movable common feed relay contact away from the fixed, normally closed relay contact and, holds it against the fixed, normally open relay contact. This action allows high current to flow to the blower motor.

When the relay coil is de-energized, spring pressure returns the movable relay contact back against the fixed, normally closed contact point. The resistor or diode is connected in parallel with the relay coil, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil collapses.

The blower motor relay terminals are connected to the vehicle electrical system through a receptacle in the integrated power module (IPM). The inputs and outputs of the blower motor relay include

1. The common feed terminal (30) receives fused battery current at all times.
2. The coil ground terminal (85) receives a ground circuit through the front control module (FCM).
3. The coil battery terminal (86) receives fused battery current at all times.
4. The normally open terminal (87) provides battery current output to the blower motor only when the blower motor relay coil is energized.
5. The normally closed terminal (87A) is not connected to any circuit in this application, but provides a battery current output only when the blower motor relay coil is de-energized.

The blower motor relay cannot be adjusted or repaired and must be replaced if inoperative or damaged. See SYSTEM WIRING DIAGRAMS for diagnosis and testing of the ISO relay and for complete HVAC wiring diagrams.

Scheme 9

1. Disconnect and isolate the negative battery cable.
2. Open the cover of the integrated power module (IPM) (1) located in the engine compartment. NOTE: Refer to the fuse and relay layout map on the IPM cover for blower motor relay identification and location.
3. Remove the blower motor relay (2) from the IPM.

The blower motor resistor has multiple resistor wires, each of which will reduce the current flow through the blower motor to change the blower motor speed. The blower motor resistor is connected to the vehicle electrical system through a dedicated wire lead and connector of the HVAC wire harness.

The blower motor speed control in the MTC heating-A/C system directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed. With the blower motor speed control in the lowest speed position, the ground path for the blower motor is applied through all of the resistor wires. Each higher speed selected with the blower motor speed control applies the ground path through fewer of the resistor wires, increasing the speed of the blower motor.

The blower motor resistor cannot be adjusted or repaired and must be replaced if inoperative or damaged (such as a cracked ceramic heat sink).

The ambient air temperature sensor is a variable resistor that operates on a ground circuit and a 5-volt reference signal circuit sent by the Front Control Module (FCM) through a two-wire lead and connector of the vehicle wire harness. The ambient air temperature sensor changes its internal resistance in response to changes in the outside air temperature, which either increases or decreases the reference signal voltage read by the FCM. The FCM converts and broadcasts the sensor data over the controller area network (CAN) B bus, where it is read by the manual temperature control (MTC) A/C-heater control and other various vehicle control modules.

The ambient air temperature sensor is diagnosed using a scan tool. Refer to DTC-Based Diagnostics/HVAC - Diagnosis and Testing .

The ambient air temperature sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged.

Scheme 10

1. Disconnect and isolate the negative battery cable.
2. Disconnect the wire harness connector (1) from the ambient air temperature sensor (2).
3. Remove the bolt (3) that secures the ambient air temperature sensor to the front bumper beam (4) and remove the sensor.

The evaporator temperature sensor monitors the temperature of the conditioned air downstream of the A/C evaporator and supplies an input signal to the A/C-heater control. The A/C-heater control uses the evaporator temperature sensor input signal to optimize A/C system performance and to protect the A/C system from evaporator freezing. The evaporator temperature sensor will change its internal resistance in response to the temperatures it monitors and is connected to the A/C-heater control through sensor ground circuit and a 5-volt reference signal circuit. As the temperature of the A/C evaporator decreases, the internal resistance of the evaporator temperature sensor decreases.

The A/C-heater control uses the monitored voltage reading as an indication of evaporator temperature and that conditions are correct to broadcast an A/C request message on the Controller Area Network (CAN) B bus, where it is read by the Front Control Module (FCM). The FCM then requests the Powertrain Control Module (PCM) to cycle the A/C compressor clutch as necessary over the CAN C bus.

The evaporator temperature sensor is diagnosed using a scan tool. Refer to DTC-Based Diagnostics/HVAC - Diagnosis and Testing .

The evaporator temperature sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged.

The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its connection to a fitting on the A/C liquid line. The A/C pressure transducer will change its internal resistance in response to the pressures it monitors. A Schrader-type valve in the liquid line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the A/C system.

The Front Control Module (FCM) provides a five volt reference signal to the A/C pressure transducer, then monitors the output voltage of the A/C pressure transducer on a sensor return circuit to determine refrigerant pressure. The FCM broadcasts a refrigerant pressure message to the Powertrain Control Module (PCM), which is programmed to respond to the A/C pressure transducer and other sensor inputs by controlling the operation of the A/C compressor clutch to help optimize A/C system performance and to protect the system components from damage. The PCM will disengage the A/C compressor clutch when high side pressure rises above 3172 kPa (460 psi) and re-engage the clutch when high side pressure drops below 1999 kPa (290 psi). The A/C pressure transducer will also disengage the A/C compressor clutch if the high side pressure drops below 193 kPa (28 psi) and will re-engage the clutch when the high side pressure rises above 234 kPa (34 psi). The A/C pressure transducer message to the PCM will also prevent the A/C compressor clutch from engaging when ambient temperatures are below about 4.5° C (40° F) due to the pressure/temperature relationship of the refrigerant.

The A/C pressure transducer is diagnosed using a scan tool. Refer to DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Diagnosis and Testing .

The A/C pressure transducer cannot be adjusted or repaired and must be replaced if inoperative or damaged.

All models are equipped with a common HVAC housing assembly (1) that combines A/C and heating capabilities into a single unit mounted within the passenger compartment. The HVAC housing consists of the following

1. HVAC housing - The HVAC housing consists of an upper housing and a lower housing that are attached together by screws and metal retaining clips and is mounted to the dash panel behind the instrument panel. The HVAC housing contains the heater core (2), blend-air doors and actuator (3), A/C evaporator (4), blower motor (7), evaporator temperature sensor (8), mode-air doors and actuators (9), floor distribution duct, foam seals and the HVAC wire harness.
2. Air inlet housing - The air inlet housing is mounted to the right end of the HVAC housing and contains the blower motor resistor (5) and the recirculation-air door and actuator (6).

The heating-A/C system is a blend-air type system. The two blend-air doors control the amount of conditioned air that is allowed to flow through, or around, the heater core. This single zone heating-A/C system uses only one blend door actuator.

The A/C system is designed for the use of a non-CFC, R-134a refrigerant and uses an A/C evaporator to cool and dehumidify the incoming air prior to blending it with the heated air. A temperature control determines the discharge air temperature by operating the blend door actuator, which moves the blend-air doors. This allows an almost immediate control of the output air temperature of the system. The two mode door actuators operate the mode-air doors which direct the flow of the conditioned air out the various air outlets, depending on the mode selected. The recirculation door actuator operates the recirculation-air door which closes off the fresh air intake and recirculates the air already inside the vehicle. The electric door actuators are connected to the vehicle electrical system by the HVAC wire harness. The blower motor controls the velocity of air flowing through the HVAC housing assembly by spinning the blower wheel within the HVAC housings at the selected speed by use of the blower motor resistor.

The HVAC housing must be removed from the vehicle and disassembled for service of the heater core, A/C evaporator, blend-air and mode-air doors. The air inlet housing must be removed from HVAC housing for service of the recirculation door actuator and the recirculation-air door.

The blower motor is used to control the velocity of air moving through the HVAC housing by spinning the blower wheel within the housing at the selected speed, whenever the ignition switch is in the On position and the blower control switch is in any position except Off.

The blower motor receives battery current whenever the ignition switch is in the Run position. Blower motor speed is controlled by regulating the path to ground through the blower motor speed control and the blower motor resistor. The blower motor circuit is protected by a fuse located in the Integrated Power Module (IPM), which is in the engine compartment.

The blower motor and blower wheel are factory balanced and cannot be adjusted or repaired. The blower motor and wheel must be replaced as an assembly if inoperative or damaged.

Possible causes of an inoperative blower motor include

1. open fuse
2. inoperative blower motor resistor
3. inoperative blower motor switch
4. inoperative blower motor relay
5. inoperative blower motor
6. inoperative mode control switch
7. inoperative blower motor circuit wiring or wire harness connectors

The A/C refrigerant lines and hoses are used to carry the refrigerant between the various A/C system components. The refrigerant lines and hoses for the R-134a A/C system consist of a barrier-hose design with a nylon tube sandwiched between rubber layers. The nylon tube helps to contain the R-134a refrigerant, which has a small molecular structure. The ends of the refrigerant lines are made from lightweight aluminum with brazed fittings.

Any kinks or sharp bends in the refrigerant lines and hoses will reduce the capacity of the entire A/C system and can reduce the flow of refrigerant within the system.

High pressures are produced in a refrigerant system when the A/C compressor is operating. Extreme care must be exercised to make sure that each of the refrigerant system connections is pressure-tight and leak free. It is a good practice to inspect all flexible hose refrigerant lines at least once a year to make sure they are in good condition and properly routed.

Depending on vehicle, model and market application, refrigerant lines are connected to each other or other A/C system components with block-type or quick-connect type fittings. To ensure the integrity of the refrigerant system, O-rings and/or gaskets may be used to seal the refrigerant system connections.

The refrigerant lines and hoses cannot be repaired and must be replaced if leaking or damaged.

When air passes through the fins of the A/C condenser, the high-pressure refrigerant gas within the A/C condenser gives up its heat. The refrigerant then condenses as it leaves the A/C condenser and becomes a high-pressure liquid. The volume of air flowing over the condenser fins is critical to the proper cooling performance of the A/C system. Therefore, it is important that there are no objects placed in front of the radiator grille openings at the front of the vehicle or foreign material on the condenser fins that might obstruct proper air flow. Also, any factory-installed air seals or shrouds must be properly reinstalled following radiator or A/C condenser service.

Note. Replacement of the refrigerant line O-ring seals and gaskets is required anytime a refrigerant line is disconnected. Failure to replace the rubber O-ring seals and metal gaskets could result in a refrigerant system leak.

The A/C condenser has no serviceable parts. The O-ring seals used on the connections are made from a special type of rubber not affected by R-134a refrigerant. The O-ring seals and gaskets must be replaced whenever a refrigerant line is disconnected from the A/C condenser.

The A/C condenser cannot be repaired and must be replaced if leaking or damaged.

Engine coolant is circulated through the heater hoses to the heater core at all times. As the coolant flows through the heater core, heat is removed from the engine and is transferred to the heater core tubes and fins. Air directed through the heater core picks up the heat from the heater core fins. The blend-air door allows control of the heater output air temperature, by regulating the amount of air flowing through the heater core. The blower motor speed controls the volume of air flowing through the HVAC housing.

The heater core cannot be repaired and must be replaced if inoperative or damaged.

Two refrigerant system service ports are used to recover/recycle/evacuate/charge and test the A/C refrigerant system. Unique sizes are used on the service ports for the R-134a refrigerant system to ensure the system is not accidentally contaminated with R-12 refrigerant or service equipment used for R-12 refrigerant.

The high side service port is located on the A/C liquid line, near the front of the engine compartment. The low side service port is located on the A/C accumulator at the rear of the engine compartment. Both the high side and low side A/C service port valve cores are serviceable.

Each of the service ports has a threaded plastic protective cap installed over it from the factory. After servicing the refrigerant system, always reinstall both of the service port caps.

Spring-lock type refrigerant line couplers are used to connect the A/C accumulator and the A/C liquid line to the A/C evaporator. Secondary retaining clips are installed over the connected couplers for added protection.

The spring-lock refrigerant line couplers require A/C Line Disconnect Tools 7193 for disengaging the two coupler halves.

Scheme 11

The spring-lock type refrigerant line coupler is held together by a garter spring (6) inside a circular cage (7) on the male half of the fitting (1). When the two coupler halves are connected, the flared end of the female fitting (2) slips behind the garter spring inside the cage on the male fitting. The garter spring and cage prevent the flared end of the female fitting from pulling out of the cage. Some applications use a connection indicator ring (4) to help indicate when the two coupler halves are fully connected.

O-rings (8) are used to seal the coupler connections. These O-rings are compatible with R-134a refrigerant and must be replaced with O-rings made of the same material.

A secondary retaining clip (3) is installed over the connected coupler (5) for added protection.

Refrigerant enters the A/C evaporator through the A/C orifice tube as a low-temperature, low-pressure mixture of liquid and gas. As air flows over the fins of the A/C evaporator, the humidity in the air condenses on the fins, and the heat from the air is absorbed by the refrigerant. Heat absorption causes the refrigerant to boil and vaporize. The refrigerant becomes a low-pressure gas when it leaves the A/C evaporator.

Note. Replacement of the refrigerant line O-ring seals and gaskets is required anytime a refrigerant line is disconnected. Failure to replace the rubber O-ring seals and metal gaskets could result in a refrigerant system leak.

The A/C evaporator has no serviceable parts except for the O-ring seals. The O-ring seals used on the connections are made from a special type of rubber not affected by R-134a refrigerant.

The A/C evaporator cannot be repaired and must be replaced if leaking or damaged.

The A/C discharge line is the refrigerant line that carries refrigerant from the A/C compressor to the A/C condenser.

The A/C discharge line has no serviceable parts except for the O-ring seals and gaskets. The O-ring seals used on the connections are made from a special type of rubber not affected by R-134a refrigerant. The O-ring seals and gaskets must be replaced whenever the A/C discharge line is removed

Note. Replacement of the refrigerant line O-ring seals and gaskets is required anytime a refrigerant line is disconnected. Failure to replace the rubber O-ring seals and metal gaskets could result in a refrigerant system leak.

The A/C discharge line has no serviceable parts except for the O-ring seals and gaskets. The O-ring seals used on the connections are made from a special type of rubber not affected by R-134a refrigerant. The O-ring seals and gaskets must be replaced whenever the A/C discharge line is disconnected.

The A/C discharge line cannot be repaired and must be replaced if leaking or damaged.

The A/C liquid line is the refrigerant line that carries refrigerant from the A/C condenser to the A/C evaporator. The A/C liquid line uses a spring-lock type refrigerant line coupler with three O-rings to connect and seal it to the A/C evaporator. See Heating and Air Conditioning/Plumbing/COUPLER, Refrigerant Line - Description .

The A/C liquid line includes the high-side service port, the fixed A/C orifice tube and a fitting for the A/C pressure transducer. See Heating and Air Conditioning/Plumbing/CORE, Service Port Valve - Description . See Heating and Air Conditioning/Plumbing/TUBE, A/C Orifice - Description and Heating and Air Conditioning/Controls/TRANSDUCER, A/C Pressure - Description .

Note. Replacement of the refrigerant line O-ring seals and gaskets is required anytime a refrigerant line is disconnected. Failure to replace the rubber O-ring seals and metal gaskets could result in a refrigerant system leak.

The A/C liquid line has no serviceable parts except for the O-ring seals, gasket, A/C pressure transducer, high-side service port valve and cap and the secondary retaining clip. The O-ring seals used on the connections are made from a special type of rubber not affected by R-134a refrigerant. The O-ring seals and gaskets must be replaced whenever the A/C liquid line is disconnected.

The A/C liquid line cannot be repaired and must be replaced if leaking or damaged.

The A/C suction line is the refrigerant line that carries refrigerant from the A/C accumulator to the A/C compressor.

Note. Replacement of the refrigerant line O-ring seals and gaskets is required anytime a refrigerant line is disconnected. Failure to replace the rubber O-ring seals and metal gaskets could result in a refrigerant system leak.

The A/C suction line has no serviceable parts except for the O-ring seals and gaskets. The O-ring seals used on the connections are made from a special type of rubber not affected by R-134a refrigerant. The O-ring seals and gaskets must be replaced whenever the A/C suction line is disconnected.

The A/C suction line cannot be repaired and must be replaced if leaking or damaged.

The refrigerant oil used in R-134a refrigerant systems is a synthetic-based, polyalkylene glycol (PAG), wax-free lubricant. Mineral-based R-12 refrigerant oils are not compatible with PAG oils, and should never be introduced to an R-134a refrigerant system.

There are different PAG oils available, and each contains a different additive package. The A/C compressor used in this vehicle is designed to use ND-8 PAG refrigerant oil. Use only this type of refrigerant oil in the refrigerant system.

After performing any refrigerant recovery or recycling operation, always replenish the refrigerant system with the same amount of the recommended refrigerant oil as was removed. Too little refrigerant oil can cause A/C compressor damage, and too much can reduce A/C system performance.

PAG refrigerant oil is more hygroscopic than mineral oil, and will absorb any moisture it comes into contact with, even moisture in the air. The PAG oil container should always be kept tightly capped until it is ready to be used. After use, recap the oil container immediately to prevent moisture contamination.

The refrigerant used in this air conditioning system is a HydroFluoroCarbon (HFC), type R-134a. Unlike R-12, which is a ChloroFluoroCarbon (CFC), R-134a refrigerant does not contain ozone-depleting chlorine. R-134a refrigerant is a non-toxic, non-flammable, clear, and colorless liquefied gas.

Even though R-134a does not contain chlorine, it must be reclaimed and recycled just like CFC-type refrigerants. This is because R-134a is a greenhouse gas and can contribute to global warming. See Heating and Air Conditioning/Plumbing - Standard Procedure .

R-134a refrigerant is not compatible with R-12 refrigerant in an A/C system. Even a small amount of R-12 refrigerant added to an R-134a refrigerant system will cause A/C compressor failure, refrigerant oil sludge or poor A/C system performance. In addition, the polyalkylene glycol (PAG) synthetic refrigerant oils used in an R-134a refrigerant system are not compatible with the mineral-based refrigerant oils used in an R-12 refrigerant system.

R-134a refrigerant system service ports, service tool couplers and refrigerant dispensing bottles have all been designed with unique fittings to ensure that an R-134a refrigerant system is not accidentally contaminated with the wrong refrigerant (R-12). There are also labels posted in the engine compartment of the vehicle and on the A/C compressor to identify that the A/C system is equipped with R-134a refrigerant.

The fixed A/C orifice tube is used to meter the flow of liquid refrigerant into the A/C evaporator. The high-pressure liquid refrigerant from the A/C condenser expands into a low-pressure liquid as it passes through the metering orifice and diffuser screen of the A/C orifice tube.

The A/C orifice tube is not serviceable and the A/C liquid line must be replaced if the orifice tube is inoperative. See Heating and Air Conditioning/Plumbing/LINE, A/C Liquid - Description .