Symptom Chart

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. 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 electronic automatic temperature control (EATC) module	Fuse(s) Circuitry short/open EATC module communication network	GO to PINPOINT TEST E .
The EATC system is inoperative, intermittent or incorrect operation	Fuse(s) Circuitry short/open EATC module	GO to PINPOINT TEST F .
Incorrect/erratic direction of airflow from outlets - manual climate control	No vacuum to the A/C control Function selector switch Vacuum hose kinked/pinched Airflow door binding/stuck Vacuum control motor A/C vacuum check valve A/C vacuum reservoir tank and bracket Vacuum actuator arm not connected to the door crank	GO to PINPOINT TEST G .
Incorrect/erratic direction of airflow from outlets - EATC	EATC module No vacuum to the A/C control Vacuum hose kinked/pinched Airflow door binding/stuck Vacuum control motor A/C vacuum check valve A/C vacuum reservoir tank and bracket Vacuum actuator arm not connected to the door crank	GO to PINPOINT TEST H .
Insufficient, erratic, or no heat - EATC and manual climate control	Low engine coolant level Engine overheating Plugged or partially plugged heater core Temperature blend door binding/stuck Temperature blend door actuator	GO to PINPOINT TEST I .
The air conditioning (A/C) is inoperative/does not operate correctly	Fuse(s) Circuitry short/open A/C cycling switch A/C system discharged/low charge A/C pressure cutoff switch EATC module Function selector switch	GO to PINPOINT TEST J .
Insufficient air conditioning (A/C) cooling	Low refrigerant level Temperature blend door actuator	CARRY OUT the refrigerant system tests. REFER to REFRIGERANT SYSTEM TESTS . If OK, GO to PINPOINT TEST A for vehicle equipped with EATC, or if equipped with manual climate control, GO to PINPOINT TEST L .
The air conditioning (A/C) is always on	Circuitry short/open A/C control relay EATC module Function selector switch	GO to PINPOINT TEST K .
Temperature control is inoperative/does not operate correctly - manual climate control	Temperature blend door actuator control Temperature blend door Temperature blend door actuator motor Circuitry open/shorted	GO to PINPOINT TEST L .
The blower motor is inoperative - manual climate control	Fuse(s) Circuitry open/shorted A/C blower motor switch A/C blower motor resistor A/C blower motor	GO to PINPOINT TEST M .
The blower motor is inoperative - EATC	Fuse(s) Circuitry short/open Blower motor relay A/C blower motor A/C blower motor speed control	GO to PINPOINT TEST N .
The blower motor does not operate correctly - manual climate control	Circuitry short/open A/C blower motor resistor A/C blower motor switch	CARRY OUT the blower motor resistor component test. If the blower motor resistor tests good, GO to PINPOINT TEST O .
The blower motor does not operate correctly - EATC	Circuitry short/open A/C blower motor speed control EATC module	GO to PINPOINT TEST P .
The steering wheel control switch is inoperative/does not operate correctly	Circuitry short/open Steering wheel control switch EATC module	GO to PINPOINT TEST Q .
The temperature set point does not repeat after turning the ignition switch OFF - EATC	Fuse(s) Circuitry short/open EATC module	CHECK circuit 1566 (RD/YE) for a short or open and repair as necessary. If OK, INSTALL a new EATC module.
The temperature display will not switch between Celsius and Fahrenheit - EATC	EATC module	PRESS the MAX A/C and DEFROST buttons simultaneously for at least 0.75 second. If the temperature display does not switch between Celsius and Fahrenheit, INSTALL a new EATC module.
Inaccurate external temperature display	EATC module	REFER to description and operation of the EATC EXTERNAL TEMPERATURE DISPLAY . If the external temperature display is not operating as described and no DTC is present, CARRY OUT the TEMPERATURE SENSOR - AMBIENT component test. If the sensor tests OK, INSTALL a new EATC module. REFER to CLIMATE CONTROL . TEST the system for normal operation.