Component Description
Climate Control - EMTC
Component Description
Heating Ventilation Air Conditioning (HVAC) Module - Electronic Manual Temperature Control (EMTC)
The blower motor speed switch is mounted in the HVAC (Heating, Ventilation, and Air Conditioning) module and controls blower motor speed by adding or bypassing resistors in the blower motor resistor in all modes except OFF. The blower motor speed switch is serviced only as an assembly with the HVAC (Heating, Ventilation, and Air Conditioning) module.
The temperature control switch adjusts the discharge air temperature. Movement of the temperature knob from cool to warm causes a corresponding movement of the temperature blend door. The position of the temperature blend door determines the discharge air temperature. The temperature control selector is an integral part of the HVAC (Heating, Ventilation, and Air Conditioning) module and cannot be serviced separately.
The airflow mode setting adjusts the discharge air outlet location. Each airflow mode selector icon causes a corresponding movement of the airflow mode doors and determines the discharge air outlet location. The airflow mode selector knob is an integral part of the HVAC (Heating, Ventilation, and Air Conditioning) module and cannot be serviced separately.
The A/C button determines A/C (Air Conditioning) compressor operation, except when the temperature selector is set to MAX A/C or the airflow mode selector is in defrost mode. The A/C button is an integral part of the HVAC (Heating, Ventilation, and Air Conditioning) module and cannot be serviced separately.
The recirculated air request button can be activated in any mode except defrost, and in any mode except MAX A/C. The recirculated air request button is an integral part of the HVAC (Heating, Ventilation, and Air Conditioning) module and cannot be serviced separately.
Air Conditioning (AC) Pressure Transducer
The PCM (Powertrain Control Module) monitors the discharge pressure measured by the A/C (Air Conditioning) pressure transducer. As the refrigerant pressure changes, the resistance of the A/C (Air Conditioning) pressure transducer changes. It is not necessary to recover the refrigerant before removing the A/C (Air Conditioning) pressure transducer.
A 5-volt reference voltage is supplied to the A/C (Air Conditioning) pressure transducer from the PCM (Powertrain Control Module). The A/C (Air Conditioning) pressure transducer receives a ground from the PCM (Powertrain Control Module). The A/C (Air Conditioning) pressure transducer then sends a voltage to the PCM (Powertrain Control Module) to indicate the A/C (Air Conditioning) refrigerant pressure.
Evaporator Temperature Sensor
The evaporator discharge air temperature sensor contains a thermistor. The sensor varies its resistance with the temperature. As the temperature rises, the resistance falls. As the temperature falls, the resistance rises.
Defrost-Panel-Floor Mode Door Actuator
The defrost/panel/floor mode door actuator contains a reversible electric motor and potentiometer. The potentiometer allows the HVAC (Heating, Ventilation, and Air Conditioning) module to monitor the position of the airflow mode door. The HVAC (Heating, Ventilation, and Air Conditioning) module drives the actuator motor in the direction necessary to move the airflow mode doors to the position set by the mode selector knob.
Temperature Blend Door Actuator
The temperature blend door actuator contains a reversible electric motor and potentiometer. The potentiometer allows the HVAC (Heating, Ventilation, and Air Conditioning) module to monitor the position of the temperature blend door. The HVAC (Heating, Ventilation, and Air Conditioning) module drives the temperature blend door actuator motor in the direction necessary to move the temperature blend door to the position set by the temperature selection knob.
Air inlet Mode Door Actuator
The air inlet mode door actuator moves the air inlet door between the fresh and recirculated air positions on command from the HVAC (Heating, Ventilation, and Air Conditioning) module. The air inlet mode door actuator is driven to, and will automatically stop at, the full recirculated air or full fresh air inlet position and does not require a potentiometer circuit to monitor its position. The airflow mode door does not stop at any point between the recirculated air or fresh air inlet position.
Air Conditioning (AC) Compressor Clutch
When battery voltage is applied to the A/C (Air Conditioning) compressor clutch field coil, the clutch disc and hub assembly is drawn toward the A/C (Air Conditioning) clutch pulley. The magnetic force locks the clutch plate and hub assembly and the A/C (Air Conditioning) clutch pulley together as one unit, causing the compressor shaft to rotate with the engine. When battery voltage is removed from the A/C (Air Conditioning) compressor clutch field coil, springs in the clutch plate and hub assembly move the clutch plate away from the A/C (Air Conditioning) clutch pulley.
An A/C (Air Conditioning) clutch diode is integrated into the coil. For A/C (Air Conditioning) clutch field coil circuit spike suppression.
Air Conditioning (AC) Compressor
The A/C (Air Conditioning) compressor has:
- a non-serviceable shaft seal.
- a pressure relief valve installed in the rear of the compressor to protect the refrigerant system against excessively high refrigerant pressures.
- PAG (Polyalkylene Glycol) oil or equivalent. This oil contains special additives required for the A/C (Air Conditioning) compressor. The oil may have some slightly dark-colored streaks while maintaining normal oil viscosity. This is normal for this A/C (Air Conditioning) compressor because of break-in wear that can discolor the oil.
Use the oil adding procedure specified for this vehicle when installing a new A/C (Air Conditioning) compressor. REFER to Refrigerant Oil Adding .
Air Conditioning (AC) Condenser
The A/C (Air Conditioning) condenser is an aluminum fin-and-tube design heat exchanger. It cools compressed refrigerant gas by allowing air to pass over fins and tubes to extract heat, and condenses gas to liquid refrigerant as it is cooled.
Evaporator Core
The evaporator core is an aluminum plate/fin type and is located in the heater core and evaporator core housing. A mixture of liquid refrigerant and oil enters the bottom of the evaporator core through the evaporator core inlet tube and continues out of the evaporator core through the evaporator core outlet tube as a vapor. During A/C (Air Conditioning) compressor operation, airflow from the blower motor is cooled and dehumidified as it flows through the evaporator core fins.
Thermostatic Expansion Valve (TXV)
The TXV (Thermostatic Expansion Valve) is located at the evaporator core inlet and outlet tubes at the center rear of the engine compartment. The TXV (Thermostatic Expansion Valve) provides a restriction to the flow of refrigerant and separates the low-pressure and high-pressure sides of the refrigerant system. Refrigerant entering and exiting the evaporator core passes through the TXV (Thermostatic Expansion Valve) through 2 separate flow paths. An internal temperature sensing bulb senses the temperature of the refrigerant flowing out of the evaporator core and adjusts an internal pin-type valve to meter the refrigerant flow into the evaporator core. The internal pin-type valve decreases the amount of refrigerant entering the evaporator core at lower temperatures and increases the amount of refrigerant entering the evaporator core at higher temperatures.
Receiver-Drier
The receiver/drier is integral to the A/C (Air Conditioning) condenser. It stores high-pressure liquid refrigerant after it leaves the condenser core.
The receiver/drier is incorporated onto the LH (Left Hand) side of the A/C (Air Conditioning) condenser. The receiver/drier desiccant bag is a separate component and can be separately removed and installed with the A/C (Air Conditioning) condenser removed from the vehicle.
Service Gauge Port Valves
The service gauge port fitting is an integral part of the refrigerant line or component.
- Special couplings are required for both the high-side and low-side service gauge ports.
- A very small amount of leakage is always detectable around the Schrader-type valve with the service gauge port valve cap removed, and is considered normal. A new Schrader-type valve core can be installed if the seal leaks excessively.
- The A/C (Air Conditioning) service gauge port valve caps are used as primary seals in the refrigerant system to prevent leakage through the Schrader-type valves from reaching the atmosphere. Always install and tighten the A/C (Air Conditioning) service gauge port valve caps to the correct torque after they are removed.
Refrigerant System Dye
A fluorescent refrigerant system dye wafer is added to the receiver/drier desiccant bag to assist in refrigerant system leak diagnosis using a Rotunda-approved UV (Ultra-violet) blacklight. This fluorescent dye wafer dissolves after about 30 minutes of continuous A/C (Air Conditioning) operation. It is not necessary to add additional dye to the refrigerant system before diagnosing leaks, even if a significant amount of refrigerant has been removed from the system. Additional refrigerant system dye should only be added if more than 50% of the refrigerant system lubricant capacity has been lost due to a fitting separation or hose rupture.
Blower Motor Resistor
The blower motor resistor uses 3 resistance elements mounted on a resistor board to provide 4 blower motor speeds. Depending on the heater blower motor switch position, series resisters are added or bypassed in the blower motor resistor to decrease or increase blower motor speed.