Thermo King 914 724, Руководство пользователя

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Electrical Maintenance (Rev. 1/99)
32
Thermostat Switch Sequence Test
The switch sequence test should be performed during
scheduled preventive maintenance operations.
NOTE: The following temperature tolerances are for tem-
peratures at or near 32 F (0 C) and may be greater near
the extremes of the setpoint range.
1. Start the unit and set the thermostat setpoint 8 to 10 F
(4.4 to 5.6 C) below the thermometer reading. The Cool
LED should be lit, the cool relay should be energized,
the Heat LED should not be lit, the heat relay should be
de-energized, and the unit should operate in cool.
2. Slowly turn the thermostat dial up to raise the thermo-
stat setpoint about 2 F (1.1 C) every 5 seconds. When
the thermostat setpoint reaches the thermometer read-
ing ± 1 F (0.6 C), the unit should shift to null. The Cool
LED should go out and the Heat LED should not be lit.
The cool relay and the heat relay should both be de-
energized.
3. Continue to slowly turn the thermostat dial up and raise
the thermostat setpoint about 2 F (1.1 C) every 5 sec-
onds. When the thermostat setpoint reaches 2 ± 1 F
(1.1 ± 0.6 C) above the thermometer reading, the unit
should shift to Heat (optional). The Heat LED should
light up and the Cool LED should not be lit. The heat
relay should be energized and the cool relay should be
de-energized.
4. Slowly turn the thermostat dial down to lower the ther-
mostat setpoint about 2 F (1.1 C) every 5 seconds.
When the thermostat setpoint reaches the thermometer
reading ± 1 F (0.6 C), the unit should shift to null. The
Heat LED should go out and the Cool LED should not
be lit. The cool relay and the heat relay should both be
de-energized.
5. Continue to slowly turn the thermostat dial down and
lower the thermostat setpoint about 2 F (1.1 C) every
5 seconds. When the thermostat setpoint reaches 2 ±
1 F (1.1 ± 0.6 C) below the thermometer reading, the
unit should shift to cool. The Cool LED should light up
and the Heat LED should not be lit. The cool relay
should be energized and the heat relay should be de-
energized.
If the unit does not shift operating modes properly, make
sure that the cool relay, the heat relay, the associated wiring,
and the wire connections are not defective before assuming
that the thermostat is faulty. Specifically:
1. Battery voltage must be present on wire 8X (T12 termi-
nal), and wire CH (T13 terminal) must be grounded at
the thermostat when the unit is turned on.
2. Terminals T5, T7, and T13 must have continuity to
each other and to the CH circuit (chassis ground).
3. The thermostat energizes the cool relay, which shifts
the unit to Cool, by sending a 12 or 24 volt signal from
the CR circuit (T8 terminal) to pin 85 of the cool relay
coil.
4. The thermostat energizes the heat relay, which shifts
the unit to heat (optional), by sending a 12 or 24 volt
signal from the HR circuit (T6 terminal) to pin 85 of the
heat relay coil.
Therefore, the thermostat is not defective if it sends a
voltage signal (12 or 24 volts) to the CR and HR circuits
properly.
Thermostat Calibration Procedure
1. Set the thermostat at 32 F (0 C).
2. Start the unit and let it run until it shifts from cool to
null.