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Home >> Mercedes Benz >> 1998 >> E430 >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> A/C-Heater Systems - Automatic >> Testing >> Function Test >> Functional Test
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Functional Test

  1. To check defrost, put temperature at a random setting. Press defrost button. If operation is correct, fan speed will increase, air will vent from defrost outlets, A/C compressor will engage, there will be maximum heat out, and inlet air will be 100 percent fresh air. If this mode does not operate properly, see DTC B1232 & B1241 , DTC B1234 , A/C PUSH-BUTTON CONTROL MODULE VOLTAGE CHECK , DTC B1416 , and DTC B1424 & B1425  under SELF-DIAGNOSTICS or TESTING.
  2. To check total ventilation in cooling mode, set temperature to LO. Press AUTO button. If this mode is operating properly, fan speed will increase, air will vent from center and side outlets, A/C compressor will engage, and there will no heat output. If this mode does not operate properly, see VACUUM SYSTEM TESTS , DTC B1234 , A/C PUSH-BUTTON CONTROL MODULE VOLTAGE CHECK , DTC 1416 , DTC B1423 , and DTC B1424 & B1425  under SELF-DIAGNOSTICS or TESTING.
  3. To check normal ventilation in regulating mode, put temperature at present in-vehicle temperature. Press AUTO button. If this mode is operating properly, fan speed will decrease, air will vent from upper outlets and leak from lower outlets, A/C compressor will be engaged, temperature of outlet air will be controlled, and duovalve and coolant pump will cycle. If this mode does not operate properly, see VACUUM SYSTEM TESTS , DTC B1232 & B1241 , A/C PUSH-BUTTON CONTROL MODULE VOLTAGE CHECK , DTC B1423 , DTC B1419 , and DTC B1424 & B1425  under SELF-DIAGNOSTICS or TESTING.
  4. To check economy (not in heating mode), set temperature to LO. Press EC button. Press dash air outlet mode. If this mode is operating properly, air will vent from dash outlets and A/C compressor will be off. If this mode does not operate properly, see VACUUM SYSTEM TESTS , DTC B1423 , and DTC B1419  under SELF-DIAGNOSTICS or TESTING.
  5. To check economy (in heating mode), set temperature to HI. Press EC button. If this mode is operating properly, air will vent from footwell and side outlets, leak from defrost outlets, and maximum heat will be output. If this mode does not operate properly, see A/C PUSH-BUTTON CONTROL MODULE VOLTAGE CHECK , DTC B1416 , DTC B1423 , DTC B1419 , or VACUUM SYSTEM TESTS  under SELF-DIAGNOSTICS or TESTING.
  6. To check Residual Engine Heat Utilization (REST), turn ignition off. Press REST button. Set temperature to 79°F. If this mode is operating properly, heated air will vent from footwell and side outlets, leak from defrost outlets, and blower will operate at low speed. If this mode does not operate properly, see VACUUM SYSTEM TESTS , A/C PUSH-BUTTON CONTROL MODULE VOLTAGE CHECK , DTC B1416 , DTC B1417 & B1418 , A/C ELECTRONIC BLOWER REGULATOR ACTIVATION , DTC B1423 , DTC B1419 , and DTC B1424 & B1425  under SELF-DIAGNOSTICS or TESTING.
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