Symptom Chart - Climate Control Systems

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retrieved, diagnose those first. Refer to the PCM DTC CHART .

SYMPTOM CHART - CLIMATE CONTROL SYSTEMS

Condition	Possible Sources	Action
No communication with the HVAC module	Fuse(s) Circuitry open HVAC module communication network	REFER to MODULE COMMUNICATIONS NETWORK -- FUSION, MILAN & MKZ article.
Unable to duplicate the customer concern and no DTCs present	HVAC system and/or related components	GO to PINPOINT TEST E .
Incorrect/erratic function in AUTO mode	Circuitry open/shorted In-vehicle temperature/humidity sensor HVAC module	GO to PINPOINT TEST F .
Reduced outlet airflow	Cabin air filter Air Conditioning Compressor Module (ACCM) Evaporator discharge air temperature sensor Blower motor Blower motor control PCM	If the airflow is reduced only when in AUTO, A/C, MAX A/C, defrost or defrost/floor modes, GO to PINPOINT TEST J . If the airflow is reduced in all modes, INSPECT the cabin air filter. If the cabin air filter is clean and free of damage and debris, GO to PINPOINT TEST L .
The air inlet door is inoperative	Circuitry open/shorted Door actuator Air inlet door binding or stuck HVAC module	GO to PINPOINT TEST G .
Incorrect/erratic direction of airflow from outlets	Circuitry open/shorted Door actuator Mode door binding or stuck HVAC module	REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION & DIAGNOSTICS -- FUSION, MILAN & MKZ (EXCEPT HYBRID) article.
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 H .
The air conditioning (A/C) is inoperative	A/C pressure transducer Evaporator discharge temperature sensor HVAC module PCM FCIM ACM ACCM	GO to PINPOINT TEST I .
The air conditioning (A/C) is always on	Evaporator discharge temperature sensor HVAC module PCM FCIM ACM ACCM	GO to PINPOINT TEST J .
Temperature control is inoperative/does not operate correctly	Circuitry open/shorted HVAC module Temperature blend door is binding or stuck Temperature blend door actuator	REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION & DIAGNOSTICS -- FUSION, MILAN & MKZ (EXCEPT HYBRID) article.
The blower motor is inoperative	Fuse(s) Circuitry short/open Blower motor relay A/C blower motor HVAC module A/C blower motor speed control	GO to PINPOINT TEST K .
The blower motor does not operate correctly	Circuitry open/shorted A/C blower motor speed control HVAC module	GO to PINPOINT TEST L .
The dual temperature control is inoperative/does not operate correctly	Temperature blend door/actuator broken/binding HVAC module - Electronic Automatic Temperature Control (EATC) Low A/C refrigerant charge	NOTE: For the passenger side temperature setting on hybrid vehicles equipped with dual-zone Electronic Automatic Temperature Control (EATC) and a Front Controls Interface Module (FCIM) built on or after 4/08/2009 to be functional, a passenger must be seated in the front passenger seat. If the front passenger seat is not occupied, the HVAC module will control the system based only on the driver side temperature setting. The HVAC module receives a Medium Speed Controller Area Network (MS-CAN) signal from the FCIM to indicate if the front passenger seat is occupied. CHECK that the A/C system pressure is above 290 kPa (42 psi). If the pressure is below 290 kPa (42 psi), REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION & DIAGNOSTICS -- FUSION, MILAN & MKZ (EXCEPT HYBRID) article. CHECK the temperature blend doors/actuators for a binding or broken condition. If no condition is found, INSTALL a new HVAC module.
The temperature display will not switch between Celsius and Fahrenheit	HVAC module	INSTALL a new HVAC module. REFER to CLIMATE CONTROL -- FUSION, MILAN & MKZ article.
Inaccurate external temperature display	HVAC module Ambient temperature sensor	REFER to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION & DIAGNOSTICS -- FUSION, MILAN & MKZ (EXCEPT HYBRID) article.