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Cold Weather Modulator (Ford Motor Co. Only)

  1. On normally open modulators (black, blue or green), cool blue and green modulators to 40°F, and black modulator to 20°F by spraying vacuum control temperature sensor with R-12 refrigerant. On normally closed modulators (yellow), warm vacuum control temperature sensor to above 70°F.
    CAUTION: Do not spray R-12 around a running engine or any other heat source. Heated R-12 vapors will create poisonous phosgene gas. Always perform this step in a well ventilated area.
  2. Connect an external vacuum source between modulator and the vacuum gauge, using a 24" length of 1/4" I.D. vacuum hose.
  3. Apply a minimum of 16 in. Hg to vacuum motor side of modulator. Modulator must not leak down to less than 5 in. Hg in 30 seconds. If it does, replace the modulator.
  4. On normally open modulators (black, blue or green), warm black, blue or green modulators to 80°F. On normally closed modulators (yellow), cool vacuum control temperature sensor with R-12 refrigerant to below 40°F. If vacuum holds at these temperatures, modulator is not functioning properly and must be replaced.
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