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Heated Air Inlet System Test

NOTE: With engine cold, heat control door in air cleaner snorkel should be closed. With engine running at normal operating temperature, door should be open.
  1. Ensure all hoses are in good condition. Using external vacuum source, apply 20 in. Hg vacuum to temperature sensor. Door should be in open position. If not, check vacuum diaphragm for leaks or restrictions.
  2. Apply 20 in. Hg vacuum to diaphragm. Diaphragm should not bleed down more than 10 in. Hg in 5 minutes. Door should not lift off bottom at less than 5.5 in. Hg. It should be fully open at no more than 8.5 in. Hg.
  3. If vacuum diaphragm does not operate properly, replace it and repeat test. If diaphragm is okay but proper temperature is not maintained, replace temperature sensor and repeat test.
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