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Home >> Lexus >> 1990 >> LS 400 >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> A/C-Heater System - Automatic >> Testing >> A/C Control Assembly >> Defogger Switch Operational Test
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Defogger Switch Operational Test

  1. Apply battery voltage to terminal IG of A/C control assembly 18-pin harness connector, and ground terminal GND. See Figure. Connect a 1.4-watt test light between terminal RDFG of A/C control assembly 18-pin connector and battery.
  2. Turn defogger switch to ON position. Ensure test light and defogger switch indicator light illuminate. Lights should go off after about 15 minutes. If switch functions as specified, check defogger relay. See DEFOGGER RELAY CHECK. If switch does not function as specified, replace A/C control panel assembly.
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