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Home >> Volkswagen >> 1993 >> Passat GL, 2.0 C, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 4-CYL >> Air Induction Systems >> Intake Air Preheating
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Intake Air Preheating

  1. Ensure control flap vacuum motor has no leaks. Separate upper and lower air filter housings. Remove air filter. Position upper housing so control flap can be seen.
  2. Disconnect vacuum hose from temperature regulator (located on air intake boot). Connect hand-held vacuum pump to control flap vacuum motor. Control flap must close cold air intake.
  3. Reconnect vacuum hose to temperature regulator. Start engine and allow it to idle. Check position of control flap after 20 seconds. Replace temperature regulator if position of control flap is not as specified in TEMPERATURE REGULATOR table.
TEMPERATURE REGULATOR

Regulator Temperature °F (°C) Control Flap Position
Less Than 68 (20) Cold Air Intake Closed
Between 68-86 (20-30) Open To Both Hot & Cold Air Intake
More Than 86 (30) Hot Air Intake Closed
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