Seats - Climate Controlled Seat Operation and Tips
TSB 06-24-911/20/06
CLIMATE CONTROLLED SEAT OPERATION AND SERVICE TIPS
LINCOLN:
2006 Zephyr
2007 MKZ
ISSUE
Some 2006 Zephyr and 2007 MKZ vehicles equipped with the climate controlled seat (CCS) option may exhibit a perceived customer concern of the seats not cooling properly with codes B2730 and B272B stored in memory. These codes may be accompanied by one (1) or both of the following DTCs B272C or B272D.
ACTION
Follow the Service Tips steps to assist in correctly resolving the condition.
SERVICE TIPS
Hardware Summary
When purchased with the CCS option, each 1st row seat in the Lincoln MKZ is fitted with two (2) Micro Thermal Modules (MTM). One (1) MTM is located under the seat cushion (near the front, in the area known as the anti-submarine ramp). The other MTM is located in the seat back cavity.
Each MTM houses a blower and a Thermo Electric Device (TED). The TED is the solid state heat pump that both heats and actively cools air that is drawn into the system. The conditioned air is directed onto the occupant (through seat foam, channel liners, spacer fabric and perforated leather trim) as a secondary source of comfort.
How the Systems Heat and Cool
The blowers draw ambient air into the system. Since the blowers are located in two (2) different positions within the seat and within the vehicle, the temperature of the air going into the back MTM and the cushion MTM may differ. The TEDs apply a temperature differential to the incoming air. In cooling, the TED is typically 14-18° F (8-10° C) less than the air surrounding the blower. When used in conjunction with the vehicle heating ventilation air conditioning (HVAC) system, it is possible that the cushion and the back may differ in their cooling response. This is primarily due to the fact that the cushion blower has better access to cooler air coming from the HVAC duct located under the seat than the back blower does.
In heating this effect is negligible due to the fact that each MTM targets an actual temperature rather than a straight differential.
System Protection
One of the protective measures on the device is that in the event that temperatures on the device get too high, the Dual Climate Controlled Seat Module (DCSM) will shut the system down. This temperature is set to 230° F (110° C) in heating and 149° F (66° C ) in cooling. Studies have shown that a temperature of 230° F (110° C) on the waste side of the TED accompanies a temperature of 149° F (66° C) on the main side in cooling mode.
In extremely hot temperatures, cabin temperatures are being recorded in excess of 149° F (66° C). If the occupant enters the vehicle during these conditions and immediately actuates the CCS system in cool mode, it is possible that the temperature on the main side of the TED will be beyond the over-temperature specification for cooling 149° F(66° C). While there is no risk to damaging the component in this situation, the DCSM interprets the condition as an over temp and will shut the system down (after a brief recovery attempt). The condition is more likely to occur with the MTM units located in the back due to the fact that they do not receive the pre-conditioned air from the vehicle HVAC unit as quickly as the cushion units. If these events occur, the DCSM will register one or both of the following fault codes (DTCs):
^ B2730: Driver Back Over-Temp
^ B272B: Passenger Back Over-Temp
These codes may be accompanied by one or both of the following DTCs:
^ B272C: Driver Differential Fault
^ B272D: Passenger Differential Fault
Differential faults occur in the event the cushion and back TEDs differ in temperature by more than 140° F (60° C). Root causes that could lead to this condition include the following:
^ Open Thermistor on 1 of the TED
^ Severe blockage of air passages in cushion or back foam
^ Open blower circuit (usually accompanied by an over-temp fault)
^ Locked impeller on the blower (foreign object stuck in impeller preventing the impeller from spinning freely - usually accompanied by an over-temp fault)
If self test is commanded while seats are in cool mode, the following DTCs will be set:
^ B103C
^ B111C
If B103C and B111C are present in the DCSM, then:
1. Clear DTCs
2. Cycle Ignition
3. Re-run self test with CCS seats in OFF mode
In the event that the system shuts down due to high cabin temperatures, the CCS system can be re-started after an ignition off / on cycle. The event is less likely to occur if the vehicle is allowed to run with HVAC system on for a period of time allowing the cabin temperature (and the seat back cavity temperature) to drop below the over-temp range.
WARRANTY STATUS: Information Only
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