Home ReviewsRefund
Home/Ford/Windstar/Ford Windstar I (1994-2003)/Repair manual/Heater/HVAC System: Overview
Contents Wiring diagrams Section: Heater All sections

HVAC System: Overview Ford Windstar I

Heater ~1689 words

DESCRIPTION & OPERATION

WARNINGVehicles are equipped with air bag supplemental restraint system. Before attempting any repairs involving steering column, instrument panel or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in appropriate AIR BAG RESTRAINT SYSTEMS article.
CAUTIONWhen battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

TEST A: ELECTRIC BLEND DOOR INOPERATIVE, INTERMITTENT OR IMPROPER OPERATION

  1. Start the vehicle and run engine until it reaches normal operating temperature. Turn heater blower motor to HI. Turn temperature adjust knob to full COOL and check for cool discharge air. Turn temperature adjust knob to full WARM and check for warm discharge air. Vary temperature adjust knob from full WARM to full COOL. If air temperature changes, the system is operating properly at this time. Check for intermittent condition. If temperature does not change, go to next step.
  2. Turn ignition switch OFF. Check fuse 21 (10A) at fuse junction panel. If the fuse is good, go to next step. If the fuse is bad service circuit 489 (PK/BK) for short to ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . Retest system.
  3. Disconnect electric blend door actuator 8-pin Connector C242. Turn ignition switch to RUN position. Using a voltmeter, check for B+ between pin 242-7, circuit 489 (PK/BK) and a known good ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is B+, go to next step. If there is not B+ service circuit 489 (PK/BK) for open. Restore vehicle. Retest system.
  4. Using an ohmmeter, check resistance between pin C242-8, circuit 57 (BK) and a known good ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is 5 ohms or less go to next step. If there is not 5 ohms or less, service circuit 57 (BK) for open. Restore vehicle. Retest.
  5. Connect electric blend door actuator 8-pin connector C242. Disconnect 3-pin connector C283 from back of potentiometer at the heater control. Using a voltmeter, check the voltage between circuit 436 (R/LG) and circuit 438 (R/W). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is reference voltage (approximately 1-2 volts) less than battery voltage, go to step 10 . If there is not, go to next step.
  6. Turn ignition switch OFF. Disconnect electronic blend door actuator connector C242. Using an ohmmeter, check resistance between pin C242-6, circuit 436 (R/LG) and potentiometer connector. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is 5 ohms or less go to next step. If there is not, service circuit 436 (R/LG) for open. Retest system.
  7. Using an ohmmeter, check for resistance between pin C242-6, circuit 438 (R/W) and potentiometer connector. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is 5 ohms or less, go to next step. If there is not, service circuit 438 (R/W) for open. Restore vehicle. Retest system.
  8. Using an ohmmeter, check resistance between pin C242-6, circuit 436 (R/LG) and a known good ground. If there is 10,000 ohms or more, go to next step. If there is not, service circuit 436 (R/LG) for short to ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . Restore vehicle. Retest system.
  9. Using an ohmmeter, check resistance between pin C242-1, circuit 438 (R/W) and a known good ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is 10,000 ohms or more, go to next step. If there is not service circuit 438 (R/W) for short to ground. Restore vehicle. Retest system.
  10. Turn ignition switch to Off. Disconnect electronic blend door actuator connector C242. Using an ohmmeter, check resistance between pin C242-2, circuit 437 (Y/LG) and potentiometer connector. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If resistance is less than 5 ohms, go to next step. If it is not, service circuit 437 (Y/LG) for open. Restore vehicle. Retest system.
  11. Using an ohmmeter, check resistance between pin C242-2, circuit 437 (Y/LG) and a known good ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is 10,000 ohms or more, go to next step. If there is not, service circuit 437 (Y/LG) for short to ground. Restore vehicle. Retest system.
  12. Disconnect and remove potentiometer. Using an ohmmeter, check resistance between terminals 2 and 3. With potentiometer at full cold, resistance should equal approximately 5,000 ohms. With potentiometer at full hot, resistance should equal approximately 300 ohms. If resistance is linearly variable between 300 and 5,000 ohms, replace electric blend door actuator. Restore vehicle. Retest system. If it is not, replace potentiometer. Restore vehicle. Retest system.

TEST B: NO OPERATION IN ALL BLOWER SETTINGS

  1. Turn ignition switch to RUN. Turn heater function selector switch to floor and heater blower motor to HI. If blower motor operates, go to next step. If it does not, go to step 5 .
  2. Rotate heater blower motor switch to LO. If the blower motor operates wiggle wires and check for intermittent operation. Service if necessary. If it does not operate, go to next step.
  3. Disconnect heater blower motor switch resistor connector C243. Using an ohmmeter, check heater blower motor resistor for resistance of coils and thermal limiter. If heater blower motor switch is good, go to next step. If it is not good, replace heater blower motor switch resister. Restore vehicle. Retest system.
  4. Disconnect blower motor connector C273. Using an ohmmeter, check resistance of circuit 361 (O/BK) between blower motor connector C273 and heater blower motor switch resister connector C243. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If resistance is 5 ohms or less, service circuit 57 (BK) between heater blower motor switch resistor connector and ground for open. Restore vehicle. Retest system. If it is not service circuit 261 (O/BK) for open. Restore vehicle. Retest system.
  5. Turn ignition switch to OFF. Ground circuit 261 (O/BK) at blower motor. Position heater function selector switch at FLOOR, and turn ignition switch to RUN long enough to check for blower motor operation. If the blower motor operates, go to next step. If it does not, go to step 8 .
  6. Disconnect blower motor connector C273. Disconnect heater blower motor switch connector C230. Using an ohmmeter, check resistance of circuit 261 (O/BK) between blower motor connector C273 and heater blower motor switch connector C230. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If resistance is 5 ohms or less, go to next step. Service circuit 261 (O/BK) for open. Restore vehicle. Retest system.
  7. Using an ohmmeter, check resistance of circuit 57 (BK) between heater blower motor switch connector C230 and a known good ground. If the resistance is less than 5 ohms, replace heater blower motor switch. Restore vehicle. Retest system. If it is not, service circuit 57 (BK) for open. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . Restore vehicle. Retest system.
  8. Turn ignition to RUN. With heater function selector switch set at floor, check for B+ at blower motor connector C273 circuit 371 (PK/W). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is B+, replace blower motor. Restore vehicle. Retest system. If there is not, go to next step.
  9. Turn ignition to RUN. With heater function selector switch set at FLOOR, check for B+ at blower motor relay connector in fuse junction panel, circuit 371 (PK/W). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is B+, service circuit 371 (PK/W) for open. Restore vehicle. Retest system. If there is not, go to next step.
  10. Check blower motor fuse 39 (30A). If it is good, go to next step. If it is not good, service circuits 364 (BK/LG) or 371 (PK/W) for short circuit. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . Restore vehicle. Retest system.
  11. Using a voltmeter, check for battery voltage at blower motor relay circuit 364 (BK/LG). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is B+, go to next step. If there is not, service circuit 364 (BK/LG) for open. Restore vehicle. Retest system.
  12. Check fuse 21 (10A). If it is good, go to next step. If it is not good, go to 16 .
  13. Pull heater control from instrument panel enough to gain access to the electrical connectors. Position heater function selector switch at FLOOR and turn ignition to RUN. Using a voltmeter, check for B+ at function selector switch Connector C247-2, circuit 249 (DB/LG). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is B+, go to step 15 . If there is not, go to next step.
  14. With same conditions as step 13) , using a voltmeter, check for B+ at the heater function selector switch Connector C247-1, circuit 489 (PK/BK). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is B+, replace heater function selector switch. Restore vehicle. Retest system. If there is not, service circuit 489 (PK/BK) between fuse panel and heater function selector switch for open. Restore vehicle. Retest system.
  15. Turn ignition to RUN. With heater function selector switch set at FLOOR, check for B+ at blower motor relay circuit 249 (DB/LG). See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is, go to step 18 . If there is not, service circuit 249 (DB/LG) for open. Restore vehicle. Retest system.
  16. Turn ignition switch OFF. Remove blower motor relay and install a new fuse. Turn ignition switch to RUN, with heater function selector switch at floor. If the fuse blows, go to next step. If it does not, replace motor relay. Restore vehicle. Retest system.
  17. Pull heater control from instrument panel enough to gain access to the electrical connectors. Disconnect connector C247 from the heater function selector switch. Install a new fuse, and turn the ignition switch to RUN. If the fuse opens, service circuit 489 (PK/BK) for short. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . Restore vehicle. Retest system. If it does not, service circuit 249 (DB/LG) for short. Restore vehicle. Retest system.
  18. Using an ohmmeter, check circuit 57 (BK) from blower motor relay to ground. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . If there is 5 ohms or less, replace blower motor relay. Restore vehicle. Retest system. If there is not, service circuit 57 (BK) for open. Restore vehicle. Retest system.

TEST C: NO OPERATION IN HIGH BLOWER SETTING

  1. Turn ignition switch to RUN. Turn heater function switch to FLOOR, and turn heater blower motor switch to HI. If the blower motor operates on HI, CYCLE heater blower motor switch from HI to LO several times. If blower operates each time, advise owner of system operation. If blower does not operate in HI each time, replace heater blower motor switch. If it does not operate on HI, go to next step.
  2. Disconnect heater blower motor switch connector C230. Check continuity of heater blower motor switch. See «BLOWER MOTOR SWITCH»(ref-138026-S27556821912002040300000) under COMPONENT TESTS. If switch is continuous in all positions service circuit 57 (BK) between heater blower motor switch and ground for open. See «WIRING DIAGRAMS»(ref-138026-S06762929072002040300000) . Restore vehicle. Retest system. If it is not continuous, replace heater blower motor switch. Restore vehicle. Retest system.

More articles — HVAC System