Sierra 3500 Denali 4WD V8-6.0L (2011)
Decreasing the TED voltage decreases the fin temperature. If the CCSM is trying to raise the fin temperature to set point by using TED voltage,
and the fin temperature cannot be raised because the TED voltage is at the maximum, the CCSM reduces the blower motor speed to achieve the
Temperature Set Point.
Cooled Seat Operation
When the cool seat switch is pressed for High Cool, the CCSM will transition to the COOL state. In response to this command, the CCSM applies a
pre-determined voltage through the ventilation module cool control circuits to the cool side of the TEDs while providing a ground through the ventilation
module heat control circuits to the heat side of the TEDs. A pre-determined voltage is also applied to the blower motors. The CCSM uses the following
sequence, beginning with the Cool SoftStart Mode, to achieve the set point temperature before it can enter the Open Loop Cool Mode.
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Cool SoftStart Mode - The intent of the Cool SoftStart Mode is for the CCSM to bring the TED fin temperature to maximum cool temperate. The
CCSM does this by setting the blower motor speed control voltage to 0 V, while ramping up the TED voltage duty cycle from 0 V to maximum
voltage duty cycle over a period not to exceed 5 seconds. Then, with the TEDs at maximum voltage, the CCSM will increase the blower speed to
maximum voltage, and keep these settings for the MAX COOL DURATION. After which the system transitions to the Open Loop Cool Mode.
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Open Loop Cool Mode - At the completion of Cool SoftStart Mode, the CCSM will initiate Open Loop Cool Mode. The intent of this mode is to
maintain the set point fin temperature based on the input of the cool seat switch. First, by controlling the speed of the blower motor, then secondly,
by controlling TED voltage. The CCSM updates these voltages once every second.
Fault State
The climate control seat system will operate normally in the battery voltage range of 9 - 16 V. If the system voltage falls outside of this voltage range, the
module will shut down all outputs until the system returns to its normal operating voltage range. The system will also transition to the fault state per the
conditions listed below, by shutting down all outputs for the seat in which the fault occurred.
High Temperature Fault State
During the heating or cooling modes, if the TED temperatures listed below are exceeded for more than 4 seconds, the system will enter the High
Temperature Fault State. At which time the CCSM will set the TED voltage duty cycle to 0%, set the blower speed control to maximum voltage to blow
ambient air over the TEDs, attempting to reduce the TED temperature below the listed maximums. The system will operate in this mode for 30 seconds.
If the over temperature fault still exists after 30 seconds, the system will transition to the FAULT state for the remainder of the ignition cycle. If the over
temperature fault clears, the system will then transition to the appropriate heat or cool softstart mode. The following temperatures are based upon
individual readings of either sensor:
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Heat mode TED temperature exceeds 230°F (110°C).
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Cool mode TED temperature exceeds 149°F (65°C).
Temperature Delta Fault
During the heating or cooling modes, if the CCSM detects a temperature difference between the seat cushion and seat back TED temperature sensors
exceeding the delta temperature listed below for more than 4 seconds, the system will enter the Temperature Delta Fault state. At which time the CCSM
will set the TED voltage duty cycle to 0%, set the blower speed control to maximum voltage to blow ambient air over the TEDs, attempting to reduce the
delta temperature to less than 68°F. The system will operate in this mode for 30 seconds. If the delta temperature fault still exists after 30 seconds, the
system will transition to the FAULT state and remain there until the ignition has been set to OFF.
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Delta between the seat cushion and seat back temperature sensors is 104°F (40°C).
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This fault state is disabled in the back only mode.
