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Cold Engine Lock-Out Test

Engine must be completely cold for this test. With the C-4144 or C-4815 tester connected to system, turn voltmeter knob to servo amp and mode knob to park, proceed as follows:

  1. Start engine and depress "LO-AUTO" pushbutton. There should be no air flow or voltmeter reading.
  2. Turn mode knob to heat. Voltmeter will show a 3 - 4.5 volt reading until full heat is reached, then it will drop approximately 0.5 volts. There should be no air flow at this time.
  3. Turn voltmeter knob to voltage. There should still be no air flow and no voltage reading.
  4. When engine coolant reaches 125°F, blower should come on at high blower speed and system will be in full heat. This should occur in a minimum of three minutes.
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