How to Troubleshoot the Climate Control System

How to Retrieve a DTC


NOTE: LHD type is shown, RHD type is symmetrical.

The climate control unit has a self-diagnostic function. To run the self-diagnostic function, do the following:

1.Set the temperature control button to Max Cool (Lo) with the ignition switch ON (II).

2.Press and hold the OFF button. While holding the OFF button, press the rear window defogger button five times within 10 seconds. Release the OFF button and the self-diagnostic will begin.

NOTE: The blower motor can be run at any speed regardless of what the panel is displaying.

 

If there is any problem in the system, the temperature indicator will light up the segment (A through N) corresponding to the error. The temperature indicator will then alternate every second between displaying ‘‘88'' (all segments lit) and the error code segment (A through N). To determine the meaning of the DTC, refer to the DTC Troubleshooting Index.

If there are no problems detected, the segments will not illuminate.

 

Canceling the Self-diagnostic Function


3.Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnostic function again to make sure that there are no other malfunctions.

Checking DTCs


To retrieve the DTC, you must run the self-diagnostic function. In the case of multiple problems, the respective indicator segments will come on. If indicator segments A, C, E, G, I and L come on at the same time, there may be an open in the common ground wire.

 

DTC (Temperature Indicator segment) Detection Item 
An open in the in-car temperature sensor circuit 
A short in the in-car temperature sensor circuit 
An open in the outside air temperature sensor circuit 
A short in the outside air temperature sensor circuit 
An open in the sunlight sensor circuit 
A short in the sunlight sensor circuit 
An open in the evaporator temperature sensor circuit 
A short in the evaporator temperature sensor circuit 
An open in the air mix control motor circuit 
A short in the air mix control motor circuit 
A problem in the air mix control linkage, door, or motor 
An open or short in the mode control motor circuit 
A problem in the mode control linkage, doors, or motor 
A problem in the blower motor circuit 

Displaying Sensor Inputs at the Climate Control Unit


The climate control unit has a mode that displays 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.

Check these items before using the sensor input display mode


1.Turn the ignition switch ON (II), 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 knob to the desired test temperature. When selecting the test temperatures, note these items:

  • ‘‘Lo'' temperature setting will default to MAX COOL, VENT, and RECIRC.
  • ‘‘Hi'' temperature setting will default to MAX HOT, FLOOR, and FRESH.
  • 16 through 32°C settings will use the automatic climate control logic.

3.Turn the ignition switch OFF.

To run the sensor input display mode, follow these steps


1.Turn the ignition switch OFF.

2.Press and hold both the AUTO and recirculation buttons, then start the engine.

3.After the engine starts, release the buttons. The display panel control unit will flash the sensor number and then the value for that sensor. Record the value displayed.

4.To advance to the next sensor, press the rear window defogger button.

Sensor Item Displayed Value 
In-car Temperature Sensor °C 
Ambient Temperature °C 
Solar Radiation Sensor Value: Dark = 00, Flashlight = 04, Cloudy =10, Sunny =65 Kcal/m2·h 
Engine coolant Temperature °C 
Evaporator Outlet Air Temperature °C 
Air Mix Opening (Low value indicates cooler air distribution, higher value indicates warmer air distribution) % of opening 
Vent Temperature Air Out (TAO) °C 

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 refer to checking DTCs by DTC indication to check for DTCs.
  • If necessary, compare the sensor input display to an alike, known-good vehicle under the same test conditions.
  • If the sensor is out of the normal range, refer to the sensor test, or substitute the sensor with a known-good, and recheck.

5.To cancel the sensor input display mode, press the AUTO button, or turn the ignition off.


Celsius to Fahrenheit Conversion Table
°C °F °C °F °C °F °C °F °C °F 
32 10 50 20 68 30 86 40 104 
34 11 52 21 70 31 88 41 106 
36 12 54 22 72 32 90 42 108 
37 13 55 23 73 33 91 43 109 
39 14 57 24 75 34 93 44 111 
41 15 59 25 77 35 95 45 113 
43 16 61 26 79 36 97 46 115 
45 17 63 27 81 37 99 47 117 
46 18 64 28 82 38 100 48 118 
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 
54 128 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 67 152 77 170 87 188 97 207 
58 136 68 154 78 172 88 190 98 208 
59 139 69 158 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 -9 
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 -58 ——— 
F0 thru F9 -50 thru -59 -58 thru -74 +100 thru +109