Component Description
Climate Control - EMTC
Component Description
Heating Ventilation Air Conditioning (HVAC) Module - Electronic Manual Temperature Control (EMTC)
The EMTC (Electronic Manual Temperature Control) system uses a remote HVAC (Heating, Ventilation, and Air Conditioning) module that is separate from the control interface. For details on the HVAC (Heating, Ventilation, and Air Conditioning) module communication, REFER to Control System Logic.
The HVAC (Heating, Ventilation, and Air Conditioning) module also controls the outputs for the interior ambient lighting, rear window defrost and heated seats.
The HVAC (Heating, Ventilation, and Air Conditioning) module utilizes an FET (Field-Effect Transistor) protective circuit strategy for its actuator outputs. Output load (current level) is monitored for excessive current (typically short circuits) and is shut down (turns off the voltage or ground provided by the module) when a fault event is detected. A short circuit DTC (Diagnostic Trouble Code) is stored at the fault event and a cumulative counter is started.
When the demand for the output is no longer present, the module resets the FET (Field-Effect Transistor) circuit protection to allow the circuit to function. The next time the driver requests a circuit to activate that has been shut down by a previous short (FET (Field-Effect Transistor) protection) and the circuit is still shorted, the FET (Field-Effect Transistor) protection shuts off the circuit again and the cumulative counter advances.
When the excessive circuit load occurs often enough, the module shuts down the output until a repair procedure is carried out. The FET (Field-Effect Transistor) protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET (Field-Effect Transistor) and the ability of the FET (Field-Effect Transistor) to withstand it. A module lifetime level of fault events is established based upon the durability of the FET (Field-Effect Transistor). If the total tolerance level is determined to be 600 fault events, the 3 predefined levels would be 200, 400 and 600 fault events.
When each tolerance level is reached, the short circuit DTC (Diagnostic Trouble Code) that was stored on the first failure cannot be cleared by a command to clear the DTCs (Diagnostic Trouble Codes). The module does not allow the DTC (Diagnostic Trouble Code) to be cleared or the circuit to be restored to normal operation until a successful self-test proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs (Diagnostic Trouble Codes) present), DTC (Diagnostic Trouble Code) U1000:00 and the associated DTC (Diagnostic Trouble Code) (the DTC (Diagnostic Trouble Code) related to the shorted circuit) automatically clears and the circuit function returns.
When each level is reached, the DTC (Diagnostic Trouble Code) associated with the short circuit sets along with DTC (Diagnostic Trouble Code) U1000:00. These DTCs (Diagnostic Trouble Codes) can be cleared using the module self-test, then the Clear DTC (Diagnostic Trouble Code) operation on the scan tool. The module never resets the fault event counter to zero and continues to advance the fault event counter as short circuit fault events occur.
If the number of short circuit fault events reach the third level, then DTCs (Diagnostic Trouble Codes) U1000:00 and U3000:49 set along with the associated short circuit DTC (Diagnostic Trouble Code). DTC (Diagnostic Trouble Code) U3000:49 cannot be cleared and a new module must be installed after the repair.
The HVAC (Heating, Ventilation, and Air Conditioning) requires PMI (Programmable Module Installation) when it is replaced.
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.
Evaporator Temperature Sensor
The evaporator 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.
In-Vehicle Temperature and Humidity Sensor
The in-vehicle temperature and humidity sensor contains 2 thermistors which separately measure the in-vehicle air temperature and humidity and send those readings to the HVAC (Heating, Ventilation, and Air Conditioning) module. The in-vehicle temperature and humidity sensor has an electric fan within the sensor that draws in-vehicle air across the thermistors.
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.
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.
Air inlet Mode Door Actuator
The air inlet 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 air inlet mode door.
Blower Motor Speed Control
The HVAC (Heating, Ventilation, and Air Conditioning) module sends a PWM (Pulse Width Modulated) signal to the blower motor speed control to control the blower speed. The blower speed control provides variable ground feed for the blower motor to control the speed. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.
Air Conditioning (AC) Compressor Clutch
When battery voltage is applied to the A/C (Air Conditioning) compressor clutch field coil, 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.
Air Conditioning (AC) Compressor
The A/C (Air Conditioning) compressor has the following characteristics:
- 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.
- The A/C (Air Conditioning) compressor uses PAG (Polyalkylene Glycol) oil or equivalent. This oil contains special additives required for the A/C (Air Conditioning) compressor.
- The A/C (Air Conditioning) compressor 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.
For Ti-VCT (Twin Independent Variable Cam Timing) engine equipped vehicles the receiver/drier is integral to the A/C (Air Conditioning) condenser.
Evaporator Core
The evaporator core is an aluminum plate/fin type and is located in the heater core and evaporator core housing.
Thermostatic Expansion Valve (TXV)
The TXV (Thermostatic Expansion Valve) is located at the evaporator core inlet and outlet tubes. The TXV (Thermostatic Expansion Valve) provides a restriction to the flow of refrigerant from the high-pressure side of the refrigerant system and separates the low-pressure and high-pressure sides of the refrigerant system.
Receiver-Drier
The receiver/drier stores high-pressure liquid and the desiccant bag mounted inside the receiver/drier removes any retained moisture from the refrigerant.
For GTDI (Gasoline Turbocharged Direct Injection) engine equipped vehicles, the receiver/drier is mounted between the A/C (Air Conditioning) condenser outlet and the TXV (Thermostatic Expansion Valve) manifold and tube assembly.
For Ti-VCT (Twin Independent Variable Cam Timing) engine equipped vehicles, 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 removed and installed with the A/C (Air Conditioning) condenser in 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 continued 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.
Cabin Air Filter
The vehicle is factory equipped with a cabin air filter. The cabin air filter is positioned at the blower motor inlet and filters both fresh and recirculated air.
A cabin air filter must be installed at all times to prevent foreign objects from entering the system. Running the system without a filter in place could result in degradation or damage to the system. The cabin air filter must be installed for correct climate control system NVH (Noise, Vibration, or Harshness) performance.
Access the cabin air filter by removing the glove compartment and the cabin air filter access cover.
Externally Controlled Variable Displacement Compressor (EVDC)
The A/C (Air Conditioning) compressor has the following characteristics:
- 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.
- The A/C (Air Conditioning) compressor uses PAG (Polyalkylene Glycol) oil or equivalent. This oil contains special additives required for the A/C (Air Conditioning) compressor.
- The A/C (Air Conditioning) compressor 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
The PCM (Powertrain Control Module) pulse width modulates the solenoid in the compressor to control the compressor displacement. The PCM (Powertrain Control Module) changes the compressor displacement based upon the:
- evaporator temperature
- ambient air temperature
- engine RPM (Revolutions Per Minute)
- vehicle speed
- A/C (Air Conditioning) high side pressure
- intake air temperature