Auto Climate Control Diagnostics
If your climate control is giving you issues, the control unit has a self-diagnostics feature, similar to the ECU.
Original writeup from TTZD.com.
Contents
Procedure
Entering Diagnostics Mode
- With the ignition switch turned ON, Press AUTO and OFF simultaneously for 5 seconds (step 2 in above image.). This will activate the Monitor Diagnosis Mode (step 3 in 1.)
- Pressing AUTO again will switch to the Actuator Test Mode (step 4 in above image.).
- Pressing AUTO again will switch to the Upper and Lower Temperature Difference Adjustment Mode (step 5 in above image.).
- Pressing AUTO again will switch to a readout of Trouble Codes (step 6 in above image.).
- Pressing AUTO again loops back to Monitor Diagnosis Mode (step 3 in above image.).
Monitoring Diagnostics Mode
The control unit will display temperature data in this mode. The step monitor will have the right single dash lit (step 3 in above image.). Temperature data is returned in the display's 'Set' digits.
Use the Mode switch and the Fan switch to toggle through the menu items.
| Def icon only |
Ambient temperature |
ºC(ºF) |
|---|---|---|
| Upper vent icon only |
Upper cabin temperature |
ºC(ºF) |
| Lower vent icon only |
Lower cabin temperature |
ºC(ºF) |
| 0 Fan & Def icon |
DEFROST outlet air temperature |
ºC(ºF) |
| 0 Fan & Upper vent icon |
VENT outlet air temperature |
ºC(ºF) |
| 0 Fan & Lower vent icon |
FOOT outlet air temperature |
ºC(ºF) |
| 1/4 Fan & Def icon |
Sunload |
*1 |
| 1/4 Fan & Upper vent icon |
water temperature *3 |
ºC(ºF) |
| 1/4 Fan & Lower vent icon |
Mode door voltage *4 |
*2 |
| 1/2 Fan & Def icon |
N/A |
|
| 1/2 Fan & Upper vent icon |
N/A |
|
| 1/2 Fan & Lower vent icon |
N/A |
|
| 3/4 Fan & Def icon |
N/A |
|
| 3/4 Fan & Upper vent icon |
N/A |
|
| 3/4 Fan & Lower vent icon |
N/A |
|
| Full fan & Upper vent icon |
Difference in upper & lower temperatures |
ºC(ºF) |
| Full fan & Lower vent icon |
N/A |
|
- 1: One tenth of the value in kcal/h*m² unit
*2: Ten times the value in V
*3: When coolant temp. is below 40ºC(104ºF), indicates 20ºC (68ºF). When coolant temp. is above 40ºC(104ºF), indicates 80ºC (176ºF)
*4 Mode door voltage: 0 = VENT, 5 = DEFROST
Actuator Test Mode
The climate controller will force actuators to work in this mode. The step monitor should be the right two dashes lit (step 4 in 1.). The 'Set' digits in the display are the Mode door voltage, 0 = VENT, 5 = DEFROST. I'm not really sure what mine means with a 49 listed. Mode and fan speed can be set independently. When the upper and lower vent icon appears, a stabilized outlet temperature 30ºC(86ºF) is reached after the air mix door has be working for about a minute.
Use the Mode switch to toggle through the menu items.
| |
Defrost icon |
Defrost and lower vent icon |
Upper and lower vent icon |
Upper vent icon |
|---|---|---|---|---|
| Mode door |
DEF |
DEF/Lower |
B/L |
VENT |
| Intake door |
FRE |
FRE |
50% FRE |
REC |
| Air mix door |
Full hot |
Full hot |
30ºC(86ºF) |
Full cold |
| Compressor |
OFF |
OFF |
ON |
ON |
operating condition of the actuators cannot be checked by indicators alone.
Use the Fan switch to toggle through the menu items.
| Blower Motor |
1/4 Fan |
1/2 Fan |
3/4 Fan |
Full fan |
|---|---|---|---|---|
| Voltage |
4V |
6V |
9V |
12V |
Upper & Lower Temperature Difference Mode
Adjustments can be made to the difference in upper and lower target temperatures in this mode. The step monitor should be 3 dashes (step 5 in 1.). The 'Set' digits in the display will show how much of a difference by 'data' numbers in relation to temperature difference.
Using the Fan and Mode switches to raise or lower the data number:
| ºC spec. |
Data |
-20 |
to |
-1 |
0 |
1 |
to |
20 |
| ºC spec. |
Difference between upper and lower target temperatures |
-2.0ºC |
to |
-0.1ºC |
0 |
0.1ºC |
to |
2.0ºC |
| ºF spec. |
Data |
-36 |
to |
-2 |
0 |
2 |
to |
36 |
| ºF spec. |
Difference between upper and lower target temperatures |
-3.6ºF |
to |
-0.2ºF |
0 |
0.2ºF |
to |
3.6ºF |
The programmed differences are stored until changed again, or the battery is disconnected.
Trouble Codes
The auto climate control stores error codes for later retrieval. The step monitor should be 2 dashes with a space in-between (step 6 in 1.). The 'Set' digits will show the number of ignition ON/OFF cycles since the problem was last detected. A dash '-' in the step monitor to the far left indicates a short circuit. A '|' hash in the step monitor on the left indicates an open circuit.
Use the Fan and Mode switches to raise or lower the code to change the desired data or status reading returned.
| Code |
Sensor |
Open circuit |
Short circuit |
|---|---|---|---|
| Defrost icon |
Ambient sensor |
Less than -70ºC(94ºF) |
Greater than 141ºC(286ºF) |
| Upper vent icon |
Cabin upper sensor |
Less than -38ºC(-36ºF) |
Greater than 141ºC(286ºF) |
| Lower vent icon |
Cabin lower sensor |
Less than -38ºC(-36ºF) |
Greater than 141ºC(286ºF) |
| 0 Fan & Def/lower vent icon*1 |
DEF duct sensor |
Less than -38ºC(-36ºF) |
Greater than 141ºC(286ºF) |
| 0 Fan & Upper vent icon |
VENT duct sensor |
Less than -38ºC(-36ºF) |
Greater than 141ºC(286ºF) |
| 0 Fan & Upper/lower vent icon*2 |
Lower duct sensor |
Less than -38ºC(-36ºF) |
Greater than 141ºC(286ºF) |
| 1/4 Fan and Def icon |
Sunload sensor |
Open circuit can not be detected w/ self diagnostic |
Greater than 1.784kW (1,534kcal/h, 6,087BTU/h)/m² [0.1657kW (142.51 kcal/h, 565.5 BTU/h)/sq ft.] |
- 1 One chart in the service manual shows 0 fan with Def/lower vent icon, while another shows 0 fan with Def icon alone.
*2 One chart in the service manual shows 0 fan with Upper/lower vent icon, while another shows 0 fan with Lower icon alone.
