How to Troubleshoot the Climate Control System
How to Check for DTCs With the HDS
NOTE:
There are three methods used to check for DTCs. The recommended method is to use the Honda Diagnostic System (HDS) with the appropriate software, plugged into the data link connector (DLC).
The second method is to run the self-diagnostic function built into the climate control unit.
The third method is to use B-CAN system diagnosis test mode A.

1.
Make sure the ignition switch is in LOCK (0), or the vehicle ignition is OFF mode.

2.
Connect the HDS to the DLC (A) located under the driver's side of the dashboard.
3.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

4.
Make sure the HDS communicates with the vehicle and the climate control unit. If it does not, go to the DLC circuit troubleshooting.

5.
Select BODY ELECTRICAL in the System Selection Menu.

6.
Select HVAC/Climate Control in the Body Electrical System Select.

7.
Select DTCs in the HVAC/Climate Control Mode Menu.

8.
Check for DTCs. If any DTCs are indicated, write down the DTCs, then go to the indicated DTC troubleshooting. If no DTCs are indicated, do all system scan, then refer to symptom troubleshooting.

NOTE:
After troubleshooting, clear the DTCs with the HDS.
For specific operations, refer to the user's manual that came with the HDS.
How to Use the Self-Diagnostic Function With the HDS
NOTE: This method is only available if the HDS can communicate with the climate control unit.

1.
Make sure the ignition switch is in LOCK (0), or the vehicle ignition is OFF mode.

2.
Connect the HDS to the DLC.

3.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

4.
Make sure the HDS communicates with the vehicle and the climate control unit. If it does not, go to the DLC circuit troubleshooting.

5.
Select BODY ELECTRICAL in the System Selection Menu.

6.
Select HVAC/Climate Control in the Body Electrical System Select.

7.
Select Inspection in the HVAC/Climate Control Mode Menu.

8.
Select Climate Control Unit Self Test in the Inspection Menu.

9.
Check for DTCs. If any DTCs are indicated, write down the DTCs, then go to the indicated DTC troubleshooting.

NOTE:
After troubleshooting, clear the DTCs with the HDS.
For specific operations, refer to the user's manual that came with the HDS.
How to Use the Self-Diagnostic Function Without the HDS
The climate control unit has a self-diagnostic function. To run the self-diagnostic function, do the following:

1.
Turn the ignition switch to LOCK (0) and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode.

2.
Press and hold the ON/OFF button, then within 10 seconds press and release the REAR WINDOW DEFOGGER/MIRROR DEFOGGER* button five times.

*: With mirror defogger

3.
ALL LCD segments come on for 2 seconds, then the self-diagnostic function begins.

NOTE:
The blower motor will run at various speeds regardless of what the panel is displaying.
If there is any problem in the system, the driver's temperature indicator flashes 88 or alternately flashes 88. Refer to checking for DTCs.
If there is more than one DTC, they are displayed one at a time in sequence followed by a pause (all the display indicator segments illuminate) between the DTCs.
If there are no problems detected, the system will flash no.
Canceling the Self-Diagnostic Function
4.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode, to cancel the self-diagnostic function. After completing repair work, run the self-diagnostic function again to make sure that there are no other DTCs.
How to Check for History DTCs
The climate control unit can record history DTCs. To read the history DTCs, do the following:

1.
Turn the ignition switch to LOCK (0) and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode.

2.
Press and hold both the AUTO and ON/OFF buttons.

3.
While pressing and holding both the AUTO and ON/OFF buttons, the history DTCs are indicated.

NOTE:
If there is any problem in the system, the driver's temperature indicator flashes 88 or alternately flashes 88. Refer to checking for DTCs.
If there is more than one DTC, they are displayed one at a time in sequence followed by a pause (all the display indicator segments illuminate) between the DTCs.
If there are no problems detected, the system will flash no.
Canceling Read History DTCs
4.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode, to cancel reading the history DTCs. After completing the repair work, clear the DTCs.
How to Clear History DTCs
1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

2.
Press and hold both the AUTO and WINDSHIELD DEFROSTER buttons, then turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

3.
After about 5 seconds the windshield defrost indicator starts to blink, release the buttons.

4.
Do the How to Check for History DTCs to verify DTCs have been cleared.
Checking for DTCs
The driver's temperature indicator display indicates single or multiple DTCs. If no DTCs are present, the indicator remains will flash no.

NOTE: If the driver's temperature indicator segments 03, 05, 07, 09, 40, 43, 49, and 55 indicator are on at the same time, there may be an open in the sensor common ground wire.

DTC (Temperature Indicator Segments)
DTC
Detection Item
03
B1225
An open in the in-car temperature sensor circuit
04
B1226
A short in the in-car temperature sensor circuit
05
B1227
An open in the outside air temperature sensor circuit
06
B1228
A short in the outside air temperature sensor circuit
07
B1229
An open in the sunlight sensor circuit
08
B1230
A short in the sunlight sensor circuit
09
B1231
An open in the evaporator temperature sensor circuit
0A
B1232
A short in the evaporator temperature sensor circuit
40
B1233
An open in the air mix control motor circuit (driver's)
41
B1234
A short in the air mix control motor circuit (driver's)
42
B1235
A problem in the air mix control motor circuit, linkage, door, or motor (driver's)
43
B1236
An open in the passenger's air mix control motor circuit
44
B1237
A short in the passenger's air mix control motor circuit
45
B1238
A problem in the passenger's air mix control motor circuit, linkage, door, or motor
49
B121A
An open in the mode control motor circuit
4A
B121B
A short in the mode control motor circuit
4B
B1240
A problem in the mode control motor circuit, linkage, door, or motor
55
B2986
An open in the recirculation control motor circuit
56
B1220
A short in the recirculation control motor circuit
57
B2983
A problem in the recirculation control motor circuit, linkage, door, or motor
59
B1241
A problem in the blower motor circuit
80
U1280
Communication bus line error (BUS-OFF)
81
U128D
Climate control unit lost communication with gauge control module (ECT message)
83
U128D
Climate control unit lost communication with gauge control module (VSP message)
91
U1281
Lost Communication with MICU
C0
???
Climate control unit internal error
Displaying Sensor Inputs at the Climate Control Unit
The climate control unit has a mode that displays the sensor inputs it receives. This mode shows you what the climate control unit is receiving from each of the sensors, one at a time, and it can help you determine if a sensor is faulty.
Checks Before Using the Sensor Input Display Mode
1.
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode, and check the recirculation door function; press the RECIRCULATION button to switch from FRESH to RECIRC. The air volume and sound should change slightly.

2.
Set the TEMPERATURE CONTROL button to the desired test temperature:
‘‘Lo’’ temperature setting will default to MAX COOL, VENT, and RECIRC (A/C on) or FRESH (A/C off).
‘‘Hi’’ temperature setting will default to MAX HOT, HEAT or HEAT/DEF, and FRESH.
USA model: 58 through 86 °F (14 through 30 °C) settings will use the automatic climate control logic.
Except USA model: 16 through 28 °C (61 through 82 °F) settings will use the automatic climate control logic.

3.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
Run the Sensor Input Display Mode
1.
Press and hold both the AUTO and RECIRCULATION buttons, then start the engine.
2.
Release both buttons. The driver's temperature indicator will flash the sensor number and then the value for that sensor. Record the value displayed.

3.
To advance to the next sensor, press the REAR WINDOW DEFOGGER/MIRROR DEFOGGER* button.

*: With mirror defogger

NOTE:
The sensor values will be displayed in degrees Celsius (°C) or an alphanumeric code. Use the chart to convert the value to degrees Fahrenheit (°F).
If the sensor value displays ‘‘Er’’, this indicates there is an open or short in the circuit or sensor. Check for DTCs using the HDS, or use the climate control self-diagnostic function.
If necessary, compare the sensor input display to a known-good vehicle under the same test conditions.
If the sensor displayed value is out of the normal range, refer to the sensor test or substitute a known-good sensor, and recheck.

Sensor
Item
Displayed Value
1
Mode positioning
%
2
In-car temperature
°C
3
Outside air temperature
°C
4
Solar radiation sensor value: dark = 00, flashlight = 04, cloudy = 10, sunny = 65
10 W/m2
5
Evaporator outlet air temperature
°C
6
Driver's air mix opening (low value indicates cooler air distribution, higher value indicates warmer air distribution)
% of opening
7
Passenger's air mix opening (low value indicates cooler air distribution, higher value indicates warmer air distribution)
% of opening
8
Recirculation control opening
% of opening
9
Vehicle speed (vehicle must be driven to display speed)
10 km/h
A
Engine coolant temperature
°C
b
Vent temperature air out (TAO) (driver's)
°C
C
Illumination duty
Step
d
Software version
?
Celsius to Fahrenheit Conversion Table
°C
°F
°C
°F
°C
°F
°C
°F
°C
°F
0
32
10
50
20
68
30
86
40
104
1
34
11
52
21
70
31
88
41
106
2
36
12
54
22
72
32
90
42
108
3
37
13
55
23
73
33
91
43
109
4
39
14
57
24
75
34
93
44
111
5
41
15
59
25
77
35
95
45
113
6
43
16
61
26
79
36
97
46
115
7
45
17
63
27
81
37
99
47
117
8
46
18
64
28
82
38
100
48
118
9
48
19
66
29
84
39
102
49
120

°C
°F
°C
°F
°C
°F
°C
°F
°C
°F
50
122
60
140
70
158
80
176
90
194
51
124
61
142
71
160
81
178
91
196
52
126
62
144
72
162
82
180
92
198
53
127
63
145
73
163
83
181
93
199
54
129
64
147
74
165
84
183
94
201
55
131
65
149
75
167
85
185
95
203
56
133
66
151
76
169
86
187
96
205
57
135
67
153
77
170
87
189
97
207
58
136
68
154
78
172
88
190
98
208
59
138
69
156
79
174
89
192
99
210
Alphanumeric Conversion Table
Display Reading (Alphanumeric)
°C
°F
%
A1 thru A9
-1 thru -9
30 thru 16
-1 thru -10
B0 thru B9
-10 thru -19
14 thru -2
-10 thru -19
C0 thru C9
-20 thru -29
-4 thru -20
-20 thru -29
D0 thru D9
-30 thru -39
-22 thru -38
-30 thru -39
E0 thru E9
-40 thru -49
-40 thru -56
-40 thru -49
E9
-50 or less
-58 or less
-50 or less
F0 thru F9
100 thru 109
212 thru 228
100 thru 109
F9
110 or more
230 or more
110 or more
Alphanumeric Conversion Table (Mode Positioning)
Display Reading (Alphanumeric)
Mode Position
0
VENT
18
HEAT/VENT
55
HEAT
70
HEAT/DEF-1
84
HEAT/DEF-2
F0
DEF