Symptom Chart

SYMPTOM CHART

Condition	Possible Sources	Action
No communication with the dual automatic temperature control (DATC) module	Fuse(s) Circuitry DATC module communication network DATC module not connected	Go To PINPOINT TEST A .
The DATC system is inoperative, intermittent or incorrect operation	Fuse(s) Circuitry Input sensors or erratic input signals Charging system In-vehicle 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 Mode 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 Coolant control valve DATC module Engine coolant thermostat	Go To PINPOINT TEST H .
Insufficient heat during engine idle	Fuse Low engine coolant level Cold engine Auxiliary coolant pump Engine coolant thermostat	Go To PINPOINT TEST I .
Full heat only in all modes	Circuitry Coolant control valve DATC module	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	Fuse 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	CHECK circuit 29-FA10 (OG/GN) for an open and REPAIR as necessary. If OK, INSTALL a new DATC module.
The temperature display will not switch between Celsius and Fahrenheit	DATC module	INSTALL a new DATC module. TEST the system for normal operation.