Symptom Chart

WARNING: This page is about a different car, the 2002 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM CHART

Condition	Possible Sources	Action
No communication with the dual automatic temperature control (DATC) module	Fuse. Circuitry. DATC module communication network. DATC module not connected.	Go To PINPOINT TEST A .
The DATC system is inoperative, intermittent or incorrectly operating	Circuitry. Input sensors or erratic input signals. Charging system. In car temperature control sensor hose and elbow (No aspiration). Air trapped in heater coolant circuits. Missing or invalid SCP messages.	Go To PINPOINT TEST B .
Incorrect/erratic direction of airflow from outlets	Circuitry. Door actuator. Airflow door binding or stuck. DATC module. Door actuator arm not connected to the door crank.	Go To PINPOINT TEST C .
Insufficient, erratic, or no heat	Circuitry. Low engine coolant level. Air trapped in heater coolant circuit. Plugged or partially plugged heater core. Bypass door actuator binding or stuck open. Coolant control valve. DATC module. Evaporator discharge air temperature sensor.	Go To PINPOINT TEST H .
Insufficient heat during engine idle	Low engine coolant level. Cold engine. Bypass door actuator binding or stuck. Auxiliary coolant pump (V8 only). Engine coolant thermostat.	Go To PINPOINT TEST I .
Full heat only in all modes	Fuse(s). Circuitry. Coolant control valve. DATC module. Evaporator discharge air temperature sensor.	Go To PINPOINT TEST J .
The dual temperature control is inoperative/does not operate correctly	Circuitry. DATC module configuration. DATC module. Coolant control valve. Low coolant level. Air trapped in coolant circuit. Incorrect heater hose connections. Air temperature sensors.	Go To PINPOINT TEST K .
The air conditioning (A/C) is inoperative/does not operate correctly	Fuse(s). Circuitry. A/C clutch relay. Evaporator discharge temperature sensor. A/C system discharged or low charge. A/C pressure transducer. DATC module. PCM.	Go To PINPOINT TEST L .
The air conditioning (A/C) is always on	Circuitry. A/C control. A/C clutch relay. Evaporator air discharge sensor. DATC module. PCM	Go To PINPOINT TEST M .
The blower motor is inoperative	Circuitry. Blower motor. Blower motor speed control. Blower motor relay. DATC module.	Go To PINPOINT TEST N .
The blower motor does not operate correctly	Blower motor speed control. DATC module. Circuitry.	Go To PINPOINT TEST O .
The temperature set point does not repeat after turning the ignition switch off	Fuse. Circuitry. DATC module.	Go To PINPOINT TEST P .
The temperature display will not switch between Celsius and Fahrenheit	DATC module.	INSTALL a new DATC module. REFER to CONTROL COMPONENTS . TEST the system for normal operation.
The exterior temperature display does not function correctly	Circuitry. DATC module. Ambient temperature sensor. Ambient temperature sensor mounting. Missing or invalid vehicle speed SCP signal.	Go To PINPOINT TEST Q .