Home/Ford/C-MAX/Ford C-MAX II (2010-2015)/Repair manual/Automatic HVAC System/HVAC - Climate Control System - General Information: Overvi…
Contents Wiring diagrams Section: Automatic HVAC System All sections

HVAC - Climate Control System - General Information: Overview Ford C-MAX II

Automatic HVAC System ~1572 words

Overview

The Dual Automatic Temperature Control (DATC) system maintains the selected vehicle interior temperature by heating and/or cooling the air depending on the HVAC control panel selection.

  1. The driver may override the automatic mode of operation.
  2. The temperature control setting is the desired cabin air temperature.
  3. The blower motor control override buttons vary the blower motor speed.
  4. The driver side and passenger side temperature settings can be individually controlled.
  5. During A/C operation, the system reduces the relative humidity of the air inside the vehicle.

HEV is equipped with an Exhaust Manifold and Catalytic Converter Assembly with coolant passages to heat engine coolant more rapidly, speeding up passenger compartment heating in cold temperatures.

Controls and Compressor Operation

Climate control commands are input through the HVAC control module. On vehicles equipped with Sony® Sound inputs can also be commanded through voice commands or the touch screen.

When the A/C is requested, the HVAC control module sends the message over the MS-CAN to the GWM . The GWM then forwards the message over the HEV High Speed Controller Area Network (HS-CAN).

The A/C demand message is sent from the SOBDMC over the HEV High Speed Controller Area Network (HS-CAN) to the ACCM . The ACCM engages the A/C electric compressor when all of the following conditions are met

  1. The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
  2. The PCM does not detect an ambient air temperature below approximately 35.6°F (2°C).
  3. The BCM does not detect an evaporator discharge air temperature below approximately 35.6°F (2°C).

The ACCM engages the A/C electric compressor when it receives the A/C demand message and target Revolutions Per Minute (RPM) request. Instead of cycling on and off like a traditional A/C compressor, the ACCM raises or lowers the A/C electric compressor speed as required.

The HVAC control module adjusts the air inlet door depending on the humidity measured by the in-vehicle temperature and humidity sensor. If the vehicle cabin becomes too humid and recirculated air is selected, the HVAC control module adjusts the air inlet door to allow more fresh air. When the humidity level drops, it may adjust back to partial recirculated air. The HVAC control module also adjusts the system based on in-vehicle temperature.

The sunload sensor supplies information to the HVAC control module indicating the intensity of the sun on the vehicle. The HVAC control module adjusts the system based on the intensity.

Normal operation and Fault Conditions

The A/C pressure transducer receives a ground from the PCM . A 5-volt reference voltage is supplied to the A/C pressure transducer from the PCM . The A/C pressure transducer then sends a voltage to the PCM to indicate the A/C pressure.

DTCDescriptionFault Trigger Conditions
P0532A/C Refrigerant Pressure Sensor "A" Circuit LowThe A/C pressure transducer inputs a feedback voltage to the PCM . This DTC sets if the feedback voltage is less than 0.26 volts for at least 2 seconds and the ambient air temperature is greater than 0°C (32°F).
P0533A/C Refrigerant Pressure Sensor "A" Circuit HighThe A/C pressure transducer inputs a feedback voltage to the PCM . This DTC sets if the feedback voltage is greater than 4.95 volts for at least 2 seconds and the ambient air temperature is greater than 0°C (32°F).

DTC FAULT TRIGGER CONDITIONS

The ACCM requires an operating voltage between 9 and 16 volts. The ACCM receives this voltage from the BJB . The ACCM has a single ground circuit located in the engine compartment wiring harness.

Excessive resistance or an open in one or more of these circuits, a discharged battery or an inoperative charging system results in the ACCM setting a DTC .

DTCDescriptionFault Trigger Conditions
P0562:00System Voltage Low: No Sub Type InformationIf the ACCM detects low voltage system voltage drops below 8.5 volts, this DTC sets after 5 seconds and the A/C electric compressor motor is stopped.

DTC FAULT TRIGGER CONDITIONS

Control System Logic

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
U0140:00Lost Communication With Body Control Module: No Sub-Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets in the HVAC control module if data messages received from the BCM over the Medium Speed Controller Area Network (MS-CAN) are missing for 5 seconds or more.

DTC FAULT TRIGGER CONDITIONS

Control System Logic

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
U0140:00Lost Communication With Body Control Module: No Sub-Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets in the ACCM if data messages received from the BCM over the High Speed Controller Area Network (HS-CAN) are missing for 5 seconds or more.

DTC FAULT TRIGGER CONDITIONS

System Operation

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

Actuator - Air Inlet Door

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

During an actuator calibration cycle, the HVAC control module drives the air inlet door until the door reaches both internal stops in the HVAC case. If the air inlet mode door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the air intake may not be from the expected source.

DTCDescriptionFault Trigger Conditions
B1083:00Recirculation Damper Motor: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) and on-demand DTC sets when the HVAC control module senses no changes in door actuator circuit when motor movement is commanded.

DTC FAULT TRIGGER CONDITIONS

During an actuator calibration cycle, the HVAC control module drives the defrost vent/register door or the footwell vent door until the door reaches the internal stops in the HVAC case. If either mode door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the airflow may not be from the expected outlets.

DTCDescriptionFault Trigger Conditions
B1085:00Defroster Damper Motor: No Sub TypeInformation This Continuous Memory Diagnostic Trouble Code (CMDTC) and on-demand DTC sets when the HVAC control module senses no changes in the feedback circuit when motor movement is commanded and no motor electrical Diagnostic Trouble Codes (DTCs) are present.
B1086:00Air Distribution Damper Motor: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) and on-demand DTC sets when the HVAC control module senses no changes in the feedback circuit when motor movement is commanded and no motor electrical Diagnostic Trouble Codes (DTCs) are present.

DTC FAULT TRIGGER CONDITIONS

When the engine is at operating temperature hot coolant flows from the electric motor through the heater core and back to the electric motor. Correct coolant temperatures are critical for good heater performance.

Control System Logic

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

Controls and Compressor

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

A/C pressure transducer

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

Evaporator Temperature Sensor

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
B11EE:19A/C Compressor: Circuit Current Above ThresholdThis DTC sets when the ACCM detects excessive voltage on the low voltage circuit.
B11EE:92A/C Compressor: Performance or Incorrect OperationThis DTC sets when the ACCM detects the number of stops due to "software overcurrent" or "start failure" exceeds a specified value.

DTC FAULT TRIGGER CONDITIONS

Control System Logic

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

Controls and Compressor Operation

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

A/C pressure transducer

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

Evaporator Temperature Sensor

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

Temperature Door Actuator - Driver Side

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

During an actuator calibration cycle, the HVAC control module drives the temperature door until the door reaches both internal stops in the HVAC case. If the temperature door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the airflow may not be the expected temperature.

DTCDescriptionFault Trigger Conditions
B1081:00Left Temperature Damper Motor: No Sub Type InformationThis DTC sets when the HVAC control module senses a short to voltage, a short to ground, or an open when motor movement is commanded.

DTC FAULT TRIGGER CONDITIONS

Temperature Door Actuator - Passenger Side

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

During an actuator calibration cycle, the HVAC control module drives the temperature door until the door reaches both internal stops in the HVAC case. If the temperature door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the airflow may not be the expected temperature.

DTCDescriptionFault Trigger Conditions
B1082:00Right Temperature Damper Motor: No Sub Type InformationThis DTC sets when the HVAC control module senses a short to voltage, a short to ground, or an open when motor movement is commanded.

DTC FAULT TRIGGER CONDITIONS

Voltage is supplied to the blower motor relay from the BJB . When the blower motor relay coil receives a ground from the BCM , the relay coil is energized and voltage is delivered to the blower motor speed control module. Voltage and ground for the blower motor is provided by the blower motor speed control. The HVAC control module sends a PWM signal to the blower motor speed control to control the blower speed.

DTCDescriptionFault Trigger Conditions
B10AF:12Blower Fan Relay: Circuit Short To BatteryThis DTC sets in continuous memory when the BCM senses voltage on the relay coil ground circuit when the module is grounding the circuit.
B10AF:13Blower Fan Relay: Circuit OpenThis DTC sets in continuous memory when the BCM senses no voltage on the relay coil ground circuit when the module is grounding the circuit.
B10AF:14Blower Fan Relay: Circuit Short To Ground or OpenThis DTC sets in continuous memory when the BCM senses no voltage on the relay coil ground circuit when the module is grounding the circuit.
B10AF:19Blower Fan Relay: Circuit Current Above ThresholdThis DTC sets in continuous memory when the BCM senses excessive voltage on the relay coil ground circuit when the module is grounding the circuit.

DTC FAULT TRIGGER CONDITIONS

Voltage is supplied to the blower motor relay from the BJB . When the blower motor relay coil receives a ground from the BCM , the relay coil is energized and voltage is delivered to the blower motor control module and ground for the blower motor is provided by the blower motor speed control. The HVAC control module sends a PWM signal to the blower motor speed control to control the blower speed.

DTCDescriptionFault Trigger Conditions
B10AF:11Blower Fan Relay: Circuit Short To GroundThis DTC sets when the BCM senses a ground on the blower motor relay coil control circuit when the relay is not grounded by the module.
B10B9:00Blower Control: No Sub Type InformationThis DTC sets when the HVAC control module senses incorrect voltage on the blower motor control PWM circuit.

DTC FAULT TRIGGER CONDITIONS

The 4 air discharge temperature sensors contain a thermistor. The sensor varies its resistance with the temperature. As the temperature rises, the resistance falls. As the temperature falls, the resistance rises.

DTCDescriptionFault Trigger Conditions
B10B3:00Right Panel Air Discharge Temperature: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses erratic voltages from the right panel air discharge temperature sensor.
B10B4:00Right Floor Air Discharge Temperature: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses erratic voltages from the right floor air discharge temperature sensor.
B10B5:00Left Panel Air Discharge Temperature: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses erratic voltages from the left panel air discharge temperature sensor.
B10B6:00Left Floor Air Discharge Temperature: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses erratic voltages from the left floor air discharge temperature sensor.

DTC FAULT TRIGGER CONDITIONS

In-Vehicle Temperature and Humidity Sensor

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
B105A:00Cabin Temperature Sensor Fan: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses no voltage or unexpected voltage on the circuit for the cabin temperature sensor fan.
B1A61:00Cabin Temperature Sensor: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses erratic voltages from the cabin temperature sensor.
B1A69:00Humidity Sensor: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses erratic voltages from the humidity sensor.

DTC FAULT TRIGGER CONDITIONS

Sunload Sensor

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
B1A63:00Right Solar Sensor: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses lower than expected voltage on an open, short to voltage or short to ground from the light sensor input circuit.
B1A64:00Left Solar Sensor: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses an open, short to voltage or short to ground from the light sensor input circuit.

DTC FAULT TRIGGER CONDITIONS

The HVAC control module requires an operating voltage between 9 and 16 volts. The HVAC control module receives this voltage from the BJB. The HVAC control module has a single ground circuit located in the engine compartment wiring harness. Excessive resistance or an open in one or more of these circuits, a discharged battery or an inoperative charging system results in the HVAC control module setting a DTC .

DTCDescriptionFault Trigger Conditions
U3006:16Control Module Input Power "A": Circuit Voltage Below ThresholdThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses lower than expected voltage.
U3006:17Control Module Input Power "A": Circuit Voltage Above ThresholdThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets when the HVAC control module senses greater than expected voltage.

DTC FAULT TRIGGER CONDITIONS

Control System Logic

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
U0155:00Lost Communication With Instrument Panel Cluster (IPC) Control Module: No Sub Type InformationThis Continuous Memory Diagnostic Trouble Code (CMDTC) sets in the HVAC control module if data messages received from the IPC over the Controller Area Network (CAN) are missing for 5 seconds or more.

DTC FAULT TRIGGER CONDITIONS

Evaporator Temperature Sensor

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
B1B71:21Evaporator Temperature Sensor: Signal Amplitude < MinimumThis DTC sets when the BCM senses lower than expected voltage on the sensor feedback circuit, indicating a short to ground.
B1B71:22Evaporator Temperature Sensor: Signal Amplitude > MaximumThis DTC sets when the BCM senses greater than expected voltage on the sensor feedback circuit, indicating a short to voltage or an open circuit or sensor.
B1B71:2FEvaporator Temperature Sensor: Signal ErraticThis DTC sets when the BCM senses erratic voltages from the evaporator temperature sensor.

DTC FAULT TRIGGER CONDITIONS

Control System Logic

REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION .

DTCDescriptionFault Trigger Conditions
U0293:00Lost Communication With Hybrid/EV Powertrain Control Module: No Sub Type InformationThis DTC sets in the ACCM if data messages received from the SOBDMC over the High Speed Controller Area Network (HS-CAN) are missing for 5 seconds or more.

DTC FAULT TRIGGER CONDITIONS

HEV is equipped with an exhaust manifold and catalytic converter assembly with coolant passages. It is used to heat engine coolant more rapidly, speeding up passenger compartment heating. This system includes an ECT sensor 2 (also known as cabin heater coolant temperature sensor) on the coolant tube that is hardwired to the PCM . When low, high or erratic voltage is sensed by the PCM on the ECT sensor 2 circuit, a DTC is set.

DTCDescriptionFault Trigger Conditions
P2184Engine Coolant Temperature Sensor 2 Circuit LowThis DTC sets when the PCM senses low voltage on the ECT sensor 2 circuit, indicating a short to ground.
P2185Engine Coolant Temperature Sensor 2 Circuit HighThis DTC sets when the PCM senses high voltage on the ECT sensor 2 circuit, indicating a short to voltage.
P2186Engine Coolant Temperature Sensor 2 Circuit Intermittent/ErraticThis DTC sets when the PCM senses erratic voltage on the ECT sensor 2 circuit, indicating an intermittent connection or a short to ground or voltage.

DTC FAULT TRIGGER CONDITIONS