Test G - System Does Not Control Temperature

WARNING: This page is about a different car, the 1996 Mercury Grand Marquis and 1996 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

Check For Diagnostic Trouble Codes

Enter self-diagnostics, and record any codes and/or temperatures displayed. See SELF-DIAGNOSTIC TEST . If Code 030 or 031 is set, go to next step. If none of these codes is set, go to step 3).
NOTE: If warm air is discharged at temperature setting of 65°F (18°C), automatic temperature control sensor circuit is open. If cool air is discharged at temperature setting of 85°F (29°C), sensor circuit is shorted.

Check Automatic Temperature Control Sensor Resistance

Unplug automatic temperature control sensor connector. Using ohmmeter, measure resistance across sensor terminals. Refer to the AUTOMATIC TEMPERATURE CONTROL SENSOR RESISTANCE table. If resistance is as specified, go to next step. If resistance is not as specified, replace sensor.

AUTOMATIC TEMPERATURE CONTROL SENSOR RESISTANCE

Temp. °F (°C)	Ohms
50-68 (10-20)	37,000-58,000
68-86 (20-30)	24,000-37,000
86-104 (30-40)	16,000-24,000

Check For Proper Installation Of Aspirator

Check installation of aspirator hose (hose draws air across automatic temperature control sensor). If hose is correctly installed, go to next step. If hose is not correctly installed, repair as necessary. Check system operation.

Check Automatic Temp Control Sensor Output At EATC Module

Turn ignition on, engine off. Disconnect automatic temperature control sensor. Using voltmeter, measure voltage at terminal No. 17 (White/Orange wire) of EATC module connector. If voltage is 5 volts, go to next step. If voltage is not 5 volts, replace EATC module. Check system operation.

Check Automatic Temperature Control Sensor Circuit

Turn ignition off. Using ohmmeter, measure resistance of White/Orange wire between EATC module and automatic temperature control sensor. If resistance is 5 ohms or less, go to next step. If resistance is not as specified, repair open White/Orange wire. Check system operation.

Check Automatic Temperature Control Sensor Return Circuit

Using ohmmeter, measure resistance of Pink/Black wire between EATC module and automatic temperature control sensor. If resistance is 5 ohms or less, replace automatic temperature control sensor. Check system operation. If resistance is not as specified, repair open Pink/Black wire. Check system operation.