Operation CHARM: Car repair manuals for everyone.
Home >> Ford >> 2009 >> F 150 4WD V8-4.6L VIN W >> Repair and Diagnosis >> Body and Frame >> Seats >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Principles of Operation >> Climate Controlled Seat >> Climate Controlled Seat System

Climate Controlled Seat System




Seats

Special Tools:






Principles of Operation

Climate Controlled Seat System

NOTICE: Avoid applying voltage directly to a Thermo-Electric Device (TED) for testing its operation. Doing so may cause damage to the TED.

NOTE: When installing a new Dual Climate Controlled Seat Module (DCSM), it is necessary to carry out Programmable Module Installation (PMI). Refer to Information Bus / Programming and Relearning. Programming and Relearning

Both the driver and front passenger climate controlled seats are independently controlled electronically by the DCSM mounted to the bottom of the passenger seat cushion. The climate controlled seat system only operates with the engine running, however, if using a scan tool to command the DCSM, diagnostic testing can be carried out with the ignition ON engine OFF in 15 second durations. The system receives voltage from Battery Junction Box (BJB) fuse 69 (30A) supplying battery voltage into the DCSM.

If one of the voltage supply circuits opens, both seats will remain operational because the circuits are connected internally in the DCSM.

Both climate controlled seats operate independently. If a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat will be disabled by the module. If the system shuts down due to a DTC fault, cycling the ignition to OFF and then ON again will reset the DCSM to function until the DTC resets.

The 4 climate controlled seat switches (identified with seat icons) on the HVAC module activate each seat system setting and illuminate indicators above each switch to indicate the operating mode. Each switch uses 3 indicators for HIGH, 2 indicators for MED and 1 indicator for LOW.

Each driver and front passenger seat cushion and backrest is equipped with a Thermo-Electric Device (TED) and blower motor assembly. Applying voltage polarity to the TED in one direction, causes it to heat. Applying voltage polarity in the opposite direction causes the TED to cool. Cabin air is drawn through the blower and distributed to each of the TED modules located in the seat cushion and backrest. The TEDs then heat or cool the incoming air depending on the control switch settings. The air is then directed into the foam pad and manifold where it is distributed along the surface of the cushion and backrest of the seat. Once activated, the DCSM maintains the heating/cooling modes until deactivated.

The temperature differences between the individual heated and cooled settings is minimal. For example, it is difficult to distinguish between LOW cool and MED cool settings. Measuring seat temperature at different settings is possible by monitoring the DCSM PIDs using the scan tool.

The HVAC module communicates climate controlled seat commands to the DCSM using the Medium Speed Controller Area Network (MS-CAN) bus. The MS-CAN bus is connected to the Data Link Connector (DLC) for diagnostic use. No direct connection exists between the DCSM and HVAC module for the climate controlled seat switches. The climate controlled seats can be commanded on or off using the scan tool to verify both module communication on the MS-CAN bus and operation of the DCSM. This method may be useful for isolating a control switch concern. Refer to Information Bus (Communications Network) for additional information concerning CAN bus communication.

Heating Characteristics

- In heat mode, the TED circuits of a given seat are wired in parallel internally in the DCSM.
- The climate controlled seat system draws approximately 24 amperes, with both seats heating, until reaching the set point and then the system operates at a reduced amperage to maintain the climate setting.
- In heat mode, the TED can add up to 40°C-60°C (72°F-108°F) to the ambient inlet air temperature as it passes over the TED.
- The system control settings are based on the 3 indicators above each climate controlled seat heat switch button on the HVAC module.
- In the LOW setting, the DCSM is set to maintain TED temperature at approximately 46°C (115°F).
- In the HIGH setting, the DCSM is set to maintain TED temperature at 65°C (149°F).
- When heating, the DCSM will vary the speed of the blowers and the TED duty cycle in order to reach and maintain the temperature determined by the switch setting (closed loop operation). Refer to the following table for heating mode temperatures.





Cooling Characteristics

- In cool mode, the TED circuits of a given seat are wired in series internally in the DCSM.
- The climate controlled seat system draws approximately 7 amps.
- In cool mode, the TED can remove up to 8°C (14°F) from the ambient air temperature entering the system.
- The system control settings are based on the 3 indicators above each climate controlled seat cool switch button on the HVAC module. The first setting is HIGH (3 indicators), the second setting is MED (2 indicators) and the third is LOW (1 indicator) then OFF (no indicators).
- When cooling, the DCSM maintains constant speed of the blowers and constant TED supply voltage (duty cycle) in open loop COOL mode (refer to the following table).





The climate controlled seat system is deactivated by one of the following actions:

- Selecting the HVAC module setting to manual OFF
- Turning the vehicle OFF

If the temperature at one of the TEDs falls below 5°C (41°F), the DCSM will shut down the TEDs and initiate system recovery mode. If the temperature continues to drop below 2°C (36°F), the DCSM will shut down the blowers in the affected seat.

Climate Controlled Seat System Recovery Mode

NOTE: The presence of overtemperature faults (DTCs B2729, B2730, B272A and B272B) can be induced by incorrect operation of the climate controlled seat system after an initial heat setting has been attained. If a heat setting is repeatedly turned OFF and ON in an attempt to increase the seat temperature or repeatedly toggled between heat and cool modes, an overtemperature condition can result and the DTCs will be set.

If the temperature at one of the TEDs rises above 110°C (230°F) in the heat mode or 65°C (149°F) in the cool mode for more than 4 seconds, the DCSM will record an overtemperature DTC, remove voltage from the TEDs and go into recovery mode (blower only) for 30 seconds to cool down the TEDs. The same will occur if a temperature difference of 60°C (108°F) or greater is seen between the backrest and cushion TEDs on either front seat. The DCSM will continue to monitor the TEDs while in recovery mode. If the temperature of the TEDs does not drop to 105°C (221°F) in the heat mode or 60°C (140°F) in the cool mode after 30 seconds, the system will continue to cool the TEDs in recovery mode for up to 5 minutes. If the TEDs cool down at anytime after 30 seconds, but before 5 minutes (checked at 4 second intervals), the system will operate as normal. An overtemperature DTC will still be recorded even if the system recovers and is operating normally. This scenario is more likely to occur during extreme cabin temperatures with significant seat back sunload. If the system does not recover within 30 seconds in heat mode or within 5 minutes in cool mode, the DCSM will disable that seat (fault mode) and remain off until the ignition is cycled. Also, if the DCSM detects temperature differential fault twice during the same ignition cycle, it will shutdown. When a fault causes a shutdown the climate controlled seat indicators will turn off and that seat will not be operational until the next key cycle.
pro multis · About Operation CHARM