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System Operates Only At Max Heat

This is usually an electrical problem. Problems outside the programmer can generally be separated from internal programmer malfunctions as follows:

  1. Set temperature dial to "65" and control lever to "ECONOMY", with system operating.
  2. Observe, programmer through slot in lower portion of cover. Programmer-should now move to Max A/C position. If so, problem is in one of the following areas:
    • Disconnected or malfunctioning in-car sensor.
    • Open circuit or backed-out terminal in 3-way connector (located under instrument panel on right side near programmer.
  3. It programmer did not move to Max A/C, problem is in one of the following areas:
    • Disconnected or defective temperature dial.
    • Disconnected or open in ground circuit (black wire) between control head and programmer.
    • Malfunction within programmer assembly.
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