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Home >> Ford >> 1988 >> Thunderbird Base, 5.0 F >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> A/C-Heater System - Automatic >> Testing >> EATC Functional Test >> System Functional Test
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System Functional Test

  1. Turn ignition off, then on, to reset system. Ensure coolant temperature is at least 120°F (49°C). With system in automatic mode, set temperature on control panel to "90°F" setting. Wait 50 seconds.
  2. Verify that system operates on high blower speed and that warm air is being discharged floor ducts. Verify that fresh/recirculated air door is in the fresh air position. Verify that warm air is bleeding out of defroster nozzle.
  3. Enter self-test and record error codes displayed. With system in automatic mode, set temperature on control panel to "60°F" setting. Verify that system operates on low blower speed and then on high blower speed as temperature setting changes.
  4. Wait 40 seconds. Verify that cool air is being discharged from panel ducts. Verify that fresh/recirculated air door is in the recirculated air position.
  5. Enter self-test, record error codes displayed, and exit self-test. Follow diagnostic procedures outlined for each error code recorded. After service or repairs, repeat system functional test. If a malfunction still exists, go to SELF-TEST INDICATES NO ERRORS FOUND test.
NOTE: When diagnosing a vehicle that is idling, it is likely that system will discharge cool air from panel ducts, even at an "85°F" temperature setting. This condition is considered normal, drive vehicle for final check.
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