Automatic A/c-Heater Systems: Overview Lincoln LS I

DESCRIPTION

Dual Automatic Temperature Control (DATC) system automatically maintains selected in-vehicle temperature with optional manual override settings. Dual temperature zone provides independent temperature set points. Driver's settings have priority over passenger settings if differences are too great. Dual zone temperature is achieved by means of a dual solenoid-operated coolant control valve. This valve individually regulates engine coolant flow to the two sections of the heater core. DATC module microcomputer analyzes inputs from temperature/blower motor speed selection, passenger compartment temperature sensor, ambient temperature sensor, engine temperature sensor and sunload sensor. (Scheme 23) System has a self-diagnostics feature in which Diagnostic Trouble Codes (DTCs) are stored in the microprocessor memory and displayed on DATC module.

Microcomputer determines A/C compressor clutch engagement, blower speed, temperature blend door position, floor/panel door position, panel/defrost door position and fresh/recirculated air door position. Small electric actuators are used to direct airflow distribution. A feedback circuit is used with actuators, enabling microcomputer to identify door position.

Scheme 23

TEST F: A/C AMBIENT TEMPERATURE SENSOR INCORRECT OPERATION

1. Turn ignition off. Disconnect ambient temperature sensor 2-pin harness connector C132, located below upper radiator support. Measure resistance between ambient temperature sensor terminals. See «TEMPERATURE SENSOR RESISTANCE»(ref-96435-S24266204942001041300000) table. If resistance is within specification, go to next step. If resistance is not within specification, replace ambient temperature sensor. Recheck system operation.
2. Turn ignition on. Measure voltage between ambient temperature sensor harness connector C132 terminals. If 4.7-5.1 volts exists, go to step 6. If 4.7-5.1 volts does not exist and DTC B1255 exists, go to next step. If 4.7-5.1 volts does not exist and DTC B1257 exists, go to step 4.
3. Turn ignition off. Disconnect DATC module 22-pin harness connector C228a. Measure resistance of White/Violet wire between DATC module harness connector C228a terminal No. 17 and ambient temperature sensor harness connector C132. see scheme 2 If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open or high resistance in White/Violet wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
4. Measure resistance between ground and DATC module harness connector C228a terminal No. 17 (White/Violet wire). If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in White/Violet wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
5. Measure resistance of Brown/White wire between DATC module harness connector C228a terminal No. 8 and ambient temperature sensor harness connector C132. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Brown/White wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
6. Disconnect DATC module 22-pin harness connector C228a. Inspect ambient temperature sensor connector pins, and DATC module harness connector C228a terminals No. 8 (Brown/White wire) and No. 17 (White/Violet wire) for damage, loose fit or improper installation. If all wiring is undamaged and properly connected, replace DATC module. Recheck system operation. If wiring shows signs of damage or incorrect connections, repair wiring as needed. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.

Scheme 24

1. Turn ignition off. Disconnect sunload sensor 4-pin harness connector C286, located on top right of instrument panel. Connect ground lead of DVOM to sunload sensor terminal No. 2 (center terminal). Measure resistance between at other sunload sensor terminals. If resistance is 38-41 k/ohms, go to next step. If resistance is not 37-41 k/ohms, replace sunload sensor. Recheck system operation.
2. Turn ignition on. Measure voltage between sunload sensor harness connector C286 terminals No. 1 (Gray/Violet wire) and No. 2 (Brown/Blue wire). Measure voltage between sunload sensor harness connector C286 terminals No. 2 (Brown/Blue wire) and No. 3 (White/Blue wire). (Scheme 24) If 4.7-5.1 volts exists at both terminals, go to step 8. If 4.7-5.1 volts does not exist at both/either terminal, go to next step.
3. Turn ignition off. Disconnect DATC module 22-pin harness connector C228a. Measure resistance between ground and DATC module harness connector C228a terminal No. 20 (Gray/Violet wire). If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in Gray/Violet wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
4. Measure resistance between ground and DATC module harness connector C228a terminal No. 20 (White/Blue wire). If resistance is more than 10 k/ohms, go to step 8. If resistance is 10 k/ohms or less, repair short to ground in White/Blue wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
5. Measure resistance of Gray/Violet wire between DATC module harness connector C228a terminal No. 20 and sunload sensor harness connector C286 terminal No. 1. see scheme 2and (Scheme 24). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Gray/Violet wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
6. Measure resistance of White/Blue wire between DATC module harness connector C228a terminal No. 7 and sunload sensor harness connector C286 terminal No. 3. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in White/Blue wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
7. Measure resistance of Brown/Blue wire between DATC module harness connector C228a terminal No. 19 and sunload sensor harness connector C286 terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open or high resistance in Brown/Blue wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.
8. Disconnect DATC module 22-pin harness connector C228a. Inspect sunload sensor connector terminals, and DATC harness connector C228a terminals No. 7 (White/Blue wire), No. 19 (Brown/Blue wire) and No. 20 (Gray/Violet wire) for damage, loose fit or improper installation. If all wiring is undamaged and properly connected, replace DATC module. Recheck system operation. If wiring shows signs of damage or incorrect connections, repair wiring as needed. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000). Recheck system operation.

TEST Q: NO OPERATION IN SOME BLOWER SPEEDS

1. Turn ignition on. Press PANEL button. Set blower speed midway between low and high. If blower motor operates, go to step 3 . If blower motor does not operate, go to next step.
2. Turn ignition on. With PANEL mode still selected, set blower speed to high. If blower motor operates, go to step 6 . If blower motor does not operate, go to «TEST O: BLOWER MOTOR INOPERATIVE OR DOES NOT OPERATE PROPERLY»(ref-96435-S02264436132001041300000) .
3. With PANEL mode still selected, set blower speed to high. If blower motor speed increases and display shows 7 bars, system is okay at this time. If blower motor speed does not increase and/or display does not change to 7 bars, go to next step.
4. Turn ignition on. Using DVOM connected to ground, measure voltage by backprobing DATC module harness connector C228b terminal No. 8 (Gray/Violet wire). If more than 9 volts, recheck all terminals for proper terminal contact. Reconnect all connectors. Recheck system operation. If system operation is still not correct, replace blower speed control. If 9 volts or less exists, go to next step.
5. Turn ignition off. Disconnect DATC module 26-pin harness connector C228b. Disconnect blower motor speed control 5-pin harness connector C297. Measure resistance of Gray/Violet wire between DATC module harness connector C228b terminal No. 8 and blower motor speed control harness connector C297 terminal No. 3. Measure resistance between ground and DATC module harness connector C228b terminal No. 8 (Gray/Violet wire). If resistance is less than 5 ohms between DATC module and blower motor speed control and more than 10 k/ohms between DATC module and ground, recheck all terminals for proper contact. Repair as necessary. Recheck system operation. If problem still exists, replace DATC module. If resistance is not less than 5 ohms between DATC module and blower motor speed control and not more than 10 k/ohms between DATC module and ground, repair open or short in Gray/Violet wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000) . Recheck system operation.
6. Set blower motor speed to low. Using DVOM connected to ground, measure voltage by backprobing DATC module harness connector C228a terminal No. 15 (Brown/Blue wire). If less than one volt exists, go to next step. If one volt or more exists, go to step 8 .
7. Turn ignition off. Disconnect 22-pin harness connector C228a. Disconnect blower motor speed control 5-pin harness connector C297. Measure resistance of Brown/Blue wire between DATC module harness connector C228a terminal No. 15 and blower motor speed control harness connector C297 terminal No. 2. Measure resistance between ground and DATC module harness connector C228a terminal No. 15 (Brown/Blue wire). If resistance is less than 5 ohms between DATC module and blower motor speed control and more than 10 k/ohms between DATC module and ground, replace blower motor speed control. Recheck system operation. If resistance is not less than 5 ohms between DATC module and blower motor speed control and not more than 10 k/ohms between DATC module and ground, repair open or short in Brown/Blue wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000) . Recheck system operation.
8. Turn ignition off. Disconnect 22-pin harness connector C228a. Disconnect blower motor speed control 5-pin harness connector C297. Measure resistance of White/Blue wire between DATC module harness connector C228a terminal No. 5 and blower motor speed control harness connector C297 terminal No. 1. Measure resistance between ground and DATC module harness connector C228a terminal No. 5 (White/Blue wire). If resistance is less than 5 ohms between DATC module and blower motor speed control and more than 10 k/ohms between DATC module and ground, replace blower motor speed control. Recheck system operation. If resistance is not less than 5 ohms between DATC module and blower motor speed control and not more than 10 k/ohms between DATC module and ground, repair open or short in White/Blue wire. See «WIRING DIAGRAMS»(ref-96435-S06818458582001041300000) . Recheck system operation.