Symptom Chart - Climate Control System

WARNING: This page is about a different car, the 2010 Lincoln MKX and 2010 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

CLIMATE CONTROL SYSTEM SYMPTOM CHART

Condition	Possible Sources	Action
No communication with the HVAC module - Dual Automatic Temperature Control (DATC)	Fuse(s) Circuitry open HVAC module - DATC communication network	REFER to MODULE COMMUNICATIONS NETWORK .
Unable to duplicate the customer concern and no DTCs present	HVAC system and/or related components	GO to PINPOINT TEST H .
Reduced outlet airflow	Circuitry short A/C compressor clutch air gap A/C cycling switch A/C clutch relay Blower motor Blower motor control Blower motor resistor Blower motor switch PCM	If the A/C compressor does not cycle, GO to PINPOINT TEST M . For Electronic Manual Temperature Control (EMTC) systems, if the A/C compressor cycles normally, GO to PINPOINT TEST R . For DATC systems, if the A/C compressor cycles normally, GO to PINPOINT TEST T .
Air inlet door is inoperative	Circuitry open/shorted HVAC module - DATC HVAC module - EMTC Air inlet door actuator/linkage	GO to PINPOINT TEST I .
Incorrect/erratic direction of airflow from outlets	Circuitry short/open Door actuator Defrost/panel/floor door actuator/linkage LH or RH blend door actuator/linkage HVAC module - EMTC or HVAC module - DATC	GO to PINPOINT TEST J .
The temperature control is inoperative/does not operate correctly - EMTC systems	Circuitry open/shorted Temperature blend door actuator Temperature blend door actuator/linkage HVAC module - EMTC	GO to PINPOINT TEST O .
The temperature control is inoperative/does not operate correctly - DATC systems	Circuitry open/shorted Temperature blend door actuator LH or RH temperature blend door actuator/linkage HVAC module - DATC	GO to PINPOINT TEST P .
Insufficient, erratic or no heat	Low engine coolant level Engine overheating Plugged or partially plugged heater core Temperature blend door is binding or stuck Temperature blend door actuator Heater hose is kinked or binding	GO to PINPOINT TEST K .
The air conditioning (A/C) is inoperative	Open fuse Circuitry short/open PCM HVAC module - EMTC or HVAC module - DATC A/C compressor A/C control relay A/C evaporator temperature sensor A/C pressure transducer Battery Junction Box (BJB)	GO to PINPOINT TEST L .
The air conditioning (A/C) is always on - A/C compressor does not cycle	Circuitry shorted PCM A/C compressor A/C control relay A/C evaporator temperature sensor A/C pressure transducer	GO to PINPOINT TEST M .
The air conditioning (A/C) is always on - A/C mode always commanded ON	Circuitry shorted PCM HVAC module - EMTC or HVAC module - DATC	GO to PINPOINT TEST N .
The blower motor is inoperative - EMTC	Fuse(s) Circuitry open A/C blower motor switch Blower motor relay A/C blower motor HVAC module -EMTC	GO to PINPOINT TEST Q .
The blower motor does not operate correctly - EMTC	Circuitry open/shorted A/C blower motor resistor A/C blower motor switch	GO to PINPOINT TEST R .
The blower motor is inoperative - DATC	Fuse(s) Circuitry open/shorted Blower motor relay A/C blower motor HVAC module - DATC Blower motor speed control	GO to PINPOINT TEST S .
The blower motor does not operate correctly - DATC	Circuitry open/shorted Blower motor speed control HVAC module - DATC A/C blower motor relay	GO to PINPOINT TEST T .
The dual temperature control is inoperative/does not operate correctly	Temperature blend door/actuator broken/binding HVAC module - DATC Low A/C refrigerant charge	CHECK that the A/C system pressure is above 290 kPa (42 psi). If the pressure is below 290 kPa (42 psi), REFER to FLUORESCENT DYE LEAK DETECTION . CHECK the temperature blend doors/actuators for a binding or broken condition. If no condition is found, INSTALL a new HVAC module - DATC .
The temperature set point does not repeat after turning the ignition switch OFF	Open fuse Circuitry short/open HVAC module - DATC	CHECK circuit SBP15 (WH/RD) for a short or open and repair as necessary. If OK, INSTALL a new HVAC module - DATC .
The temperature display will not switch between Celsius and Fahrenheit	HVAC module - DATC Instrument Cluster (IC) module	If the IC does not switch between English and Metric, REFER to INSTRUMENT CLUSTER AND PANEL ILLUMINATION . If only the HVAC module - DATC does not switch between English and Metric, INSTALL a new HVAC module - DATC .
Inaccurate external temperature display	HVAC module - DATC Ambient temperature sensor	REFER to DESCRIPTION AND OPERATION of the External Temperature Display. If the external temperature display is not operating as described and no DTC is present, CARRY OUT the Ambient Temperature Sensor component test. See Component Tests . If the sensor tests OK, INSTALL a new HVAC module - DATC . REFER to CLIMATE CONTROL . TEST the system for normal operation.