NHTSA ID Number: 10240131
Manufacturer Communication Number: SB54-338
TSB/Document Date: 2023-08-05
Summary
Revised Service Bulletin for Updating HVAC ECU Software to Fix Front HVAC Evaporator Freezing and Improve Espar Heater Cool Down. Description of Revisions: This bulletin replaces the version dated December 2021. The general information and warranty information has been updated.
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TSB/Document ID: SB54-338
Replacement Service Bulletin Number:
MFR Communication Date: 2023-07-13
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: VISIBILITY
MFR Component System:
MFR Component Subsystem:
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Updating HVAC ECU Software to Fix Front HVAC
Evaporator Freezing and Improve Espar Heater Cool Down
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional
Century Class Conventional
Argosy
Cargo
Columbia
122SD and Coronado
Business Class M2
Cascadia
108SD/114SD
> New Cascadia
54-338
Freightliner
Service Bulletin
Description of Revisions: This bulletin replaces the version dated
December 2021. The general information and warranty information
has been updated.
General Information
New Cascadia vehicles with sleeper cabs may become extremely cold when in A/C mode, which can lead to
reduced airflow as a result of internal ice buildup at the evaporator.
Conditions that contribute to the front evaporator freezing include:
• Engine at 900 rpm and above, typically noticed when vehicle is moving at 60 mph (97 km/h) or more.
• Air conditioning in recirculation mode; the front evaporator may freeze in ECO mode but it will take much
longer.
• Blower motor operating at 50% power or above.
• Temperature control knob turned to the full cold setting.
• Ambient temperature approximately 86°F (30°C) or above.
• Humidity at 75% or higher.
There are also issues with the durability of the Espar D5 heater system when paired with the battery parked
HVAC system (BPHS). This can be improved by applying "cool down" software to the parked electronic control
unit (ECU) HVAC_P01T.
The front evaporator freezing issue is addressed by the new software available for the front ECU HVAC_F01T
and auxiliary ECU HVAC_R01T.
This software is now available and should be installed. The software is backwards compatible for all ECUs.
Each vehicle will require the software updates listed.
For vehicles without a BPHS or ParkSmart unit, install the software listed in Table 1. If a newer version of the
software listed is available, install that.
DiagnosticLink Software Updates for Vehicles without a BPHS or ParkSmart Unit
Controller
Front (F01T)
Rear (R01T)
Sw Version
21.28.01
21.28.01
Sw Part Number
001 448 14 28 ZGS 001
001 448 07 28 ZGS 001
Table 1, DiagnosticLink Software Updates for Vehicles without a BPHS or ParkSmart Unit
For vehicles with a BPHS, install the software listed in Table 2. If a newer version of the software listed is
available, install that.
Controller
Sw Version
Sw Part Number
DiagnosticLink Software Updates for Vehicles with a BPHS
Front (F01T)
Rear (R01T)
Parked (P01T)
21.28.01
21.28.01
20.35.1
001 448 14 28 ZGS 001
001 448 07 28 ZGS 001
000 448 70 28 ZGS 007
Table 2, DiagnosticLink Software Updates for Vehicles with a BPHS
For vehicles with a ParkSmart unit, install the software listed in Table 3. If a newer version of the software listed
is available, install that.
Freightliner Service Bulletin, 07/13/2023
Page 1
54-338
Freightliner
Service Bulletin
Updating HVAC ECU Software to Fix Front HVAC
Evaporator Freezing and Improve Espar Heater Cool Down
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional
Century Class Conventional
Argosy
Cargo
Columbia
122SD and Coronado
Business Class M2
Cascadia
108SD/114SD
> New Cascadia
DiagnosticLink Software Updates for Vehicles with a ParkSmart Unit
Controller
Front (F01T)
Rear (R01T)
Parked (P01T)
Sw Version
21.28.01
21.28.01
20.35.1
Sw Part Number
001 448 14 28 ZGS 001
001 448 07 28 ZGS 001
000 448 68 28 ZGS 003
Table 3, DiagnosticLink Software Updates for Vehicles with a ParkSmart Unit
After the HVAC_P01T software has been updated, drivers may notice the Espar combustion chamber fan and
coolant pump running for approximately three minutes after the Espar D5 heater has turned off.
Warranty
This is an informational bulletin only. Warranty does not apply.
Page 2
Freightliner Service Bulletin, 07/13/2023
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