Adjusting Automatic Temperature Control Range with
Optimized Idle
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

54-322
Freightliner
Service Bulletin

Description of Revisions: This bulletin replaces the version dated
12/06/2019. Tables 3 and 4 have been updated. Steps to change
and match HVAC desired settings have been updated.

General Information
Under normal driving conditions, front and rear HVAC systems operate as independent constant outlet
temperature control (COTC) systems when Optimized Idle™ (OI) is not armed. The desired outlet temperature is
selected directly with the temperature selection knobs. When OI is armed, HVAC systems change to an
automatic temperature control (ATC) system, and operate as follows:
• When the engine OFF, blowers are disabled;
• when the engine is ON for Battery Mode or OI oil temperature, cabin temperature is maintained at the
selected set-point;
• minimum blower speed (engine on) is elevated to speed 4;
• desired cabin temperature and blower speed is selected from the sleeper controls;
• front controls are disabled prior to 18.44.01 SW;
• with 18.44.01 SW and later, front blower speed and temperature setting are by default controlled to the
settings on the rear controller. However, if front blower speed and temperature settings are subsequently
adjusted after arming OI, front HVAC control will temporally switch back to normal COTC mode, and be
controlled to the front HVAC settings, for a duration of 10 minutes.;
• temperature range is re-mapped to a smaller range for automatic temperature control; and
• recirculation mode defaults to outside air.
Refer to Table 1 and Table 2 to understand the change from COTC to ATC in OI Comfort Mode.

NOTE: When the low temperature parameter is changed (step 19) the value for detent 1 changes
from 60 to the selected value. Temperatures for all detents in between detent 1 and 21 will then be
mapped linearly.
Blower Detent
Blower Detent
Blower Detent Mapping
0
0
1
4
2
4
3
4
4
4
5
5
6
6
7
7
8
8
9
9
10
10
Table 1, Blower Detent

Freightliner Service Bulletin, 04/19/2021

Page 1

54-322
Freightliner
Service Bulletin

Adjusting Automatic Temperature Control Range with
Optimized Idle
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

Temperature Detent
Temperature
Detent
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

Temperature Scaling (°F)

Temperature Scaling (°C)

60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

15.6
16.1
16.7
17.2
17.8
18.3
18.9
19.4
20.0
20.6
21.1
21.7
22.2
22.8
23.3
23.9
24.4
25.0
25.6
26.1
26.7

Table 2, Temperature Detent

Optimized Idle Comfort Mode
Optimized Idle in comfort mode operates under the following conditions:
• If "Comfort Mode YES" is selected when OI is armed, the Rear HVAC controller is enabled to request the
CPC to start engine, to support cabin comfort.
• If the interior temperature exceeds Cooling Upper Hysteresis, the engine is requested ON for Cooling;
HVAC is set to Full Cold until Cooling Lower Hysteresis is reached.
• If the interior temperature falls below Heating Lower Hysteresis, the engine is requested ON for heating;
HVAC is set to Full Hot until Heating Upper Hysteresis is reached.
The HVAC automatically switches between heating and cooling modes, and maintains cabin temperature within
heating or cooling hysteresis bands. The default width is 9.9°F.
OI hysteresis band width is defined by the Par_HVAC_Controller_Hysteresis on the rear HVAC along with the
Par_HVAC_Controller_Hysteresis on the front HVAC controllers. Both units must be paired correctly for OI
comfort mode to work properly. See Table 3 and Table 4.

Page 2

Freightliner Service Bulletin, 04/19/2021

Adjusting Automatic Temperature Control Range with
Optimized Idle
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Hex
0x14

Century Class Conventional
Argosy
Cargo
Columbia
122SD and Coronado

Business Class M2
Cascadia
108SD/114SD
> New Cascadia

54-322
Freightliner
Service Bulletin

Controller Hysteresis Prior to Software Version 18.44.01
Heating
Cooling
HVAC_R
Range
Parameter
Upper
Lower
Upper
Lower
A 018 447 20
+3.6°F
-6.3°F
+6.3°F
-3.6°F
-9.9°F
28

HVAC_F
Parameter
A 017 447 90
28

Table 3, Controller Hysteresis Prior to Software Version 18.44.01

Hex
0x0A
0x14
0X1E
0x28
0x32
0x3C

New Controller Hysteresis, Compatible with Software Version 18.44.01
Heating
Cooling
Parameters
Range
Upper
Lower
Upper
Lower
HVAC_R Parameter
HVAC_F Parameter
+4°F
-6°F
+6°F
-4°F
10°F
A 018 447 27 28
A 017 447 97 28
+3.6°F
-6.3°F
+6.3°F
-3.6°F
9.9°F
A 018 447 20 28
A 017 447 90 28
+3°F
-5°F
+5°F
-3°F
8°F
A 018 447 28 28
A 018 447 96 28
+2.5°F
-4.5°F
+4.5°F
-2.5°F
7°F
A 017 447 51 28
A 017 447 95 28
+1.5°F
-3.5°F
+3.5°F
-1.5F
5°F
A 017 447 52 28
A 017 447 93 28
+1°F
-3°F
+3°F
-1°F
4°F
A 017 447 53 28
A 017 447 92 28
Table 4, New Controller Hysteresis, Compatible with Software Version 18.44.01

Use the instructions in this bulletin to reduce the hysteresis and improve driver comfort in ATC mode.

Setup Instructions
1. Park the vehicle, apply the parking brakes, and shut down the engine. Chock the tires.
2. Connect the vehicle to DiagnosticLink. Make sure that DiagnosticLink is updated to the latest version, 8.10,
or newer. To update DiagnosticLink, select "Update" from the dropdown menu under "Tools." See Fig. 1.
It is recommended when flashing to configure DiagnosticLink to connect only to "Default" modules, and stay
in this configuration unless it is specifically needed to manually connect to the Common Telematics Platform
(cTP) ECU. Default modules allow DiagnosticLink to connect only to the modules that need flashing, and
ignores things like the cTP or the steering angle sensor.
To make this change in DiagnosticLink:
• From the top click "Tools", and select "Options" form the drop down menu.
• Find and select the "Connection" tab.
• Click the "Select Defaults" box on the right side of the tab, and select "Apply."

Freightliner Service Bulletin, 04/19/2021

Page 3

54-322
Freightliner
Service Bulletin

Adjusting Automatic Temperature Control Range with
Optimized Idle
FLA COE
FLB COE
FLD Conventional
Business Class
FLC 112 Conventional

Century Class Conventional
Argosy
Cargo
Columbia
122SD and Coronado

01/15/2021

Business Class M2