Compartment Temperature Is Excessively Lower Than Setting Temperature

Trouble symptom: 

Compartment temperature is excessively lower than setting temperature.

Trouble causes: 

• Large airflow capacity
• Refrigerant pressure failure
• CAN communication failure
• A/C control panel failure
• Air mix actuator RH failure
• Air mix actuator LH failure (only with left/right independent air conditioning function)
• Evaporator sensor failure
• In-vehicle sensor failure
• Ambient sensor failure
• Sunload sensor failure

1. CHECK AIRFLOW CAPACITY. 

   Check the airflow capacity. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostics with Phenomenon>INSPECTION>AIR GOES OUT OF CONTROL .

   Is the check result OK?

   • Yes  : Go to 2. 
   • No  : Perform repair according to inspection procedure.
2. CHECK AMOUNT OF REFRIGERANT PRESSURE. 

   Check the refrigerant pressure. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Refrigerant Pressure with Manifold Gauge Set>PROCEDURE>CHECK REFRIGERANT GAS PRESSURE .

   Is the check result OK?

   • Yes  : Go to 3. 
   • No  : Perform repair according to refrigerant pressure inspection.
3. CHECK A/C CONTROL PANEL. 
   1. Turn the temperature control dials (driver's side) and (passenger's side) to MAX COOL.
   2. Using Subaru Select Monitor, check the following data of the data monitor. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Data Monitor .
      • Heater Control Panel Setting Value (Driver's)
      • Heater Control Panel Setting Value (Passenger's)

   Do [Heater Control Panel Setting Value (Driver's)] and [Heater Control Panel Setting Value (Passenger's)] indicate "60" *1?

   • Yes  : Go to 4. 
   • No  : Replace the A/C control panel Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Control Panel>REMOVAL .
4. CHECK A/C CONTROL PANEL. 
   1. Turn the temperature control dials (driver's side) and (passenger's side) to MAX HOT.
   2. Using Subaru Select Monitor, check the following data of the data monitor. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Data Monitor .
      • Heater Control Panel Setting Value (Driver's)
      • Heater Control Panel Setting Value (Passenger's)

   Do [Heater Control Panel Setting Value (Driver's)] and [Heater Control Panel Setting Value (Passenger's)] indicate "90" *2?

   • Yes  : Go to 5. 
   • No  : Replace the A/C control panel. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Control Panel>REMOVAL .
5. CHECK DTC. 
   1. Turn the ignition switch to ON.
   2. Turn the temperature control dial at MAX COOL and leave for 16 seconds or more. (For vehicles with left/right independent air conditioner, perform setting on both sides.)
   3. Read the DTC using Subaru Select Monitor. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

   Is DTC B14E1, B14E2, B14E3 or B14E4 displayed?

   • Yes  : Perform the diagnosis for the displayed DTC B14E1, B14E2, B14E3 or B14E4. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E1 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT OPEN (DRIVER) . Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E2 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT SHORT-CIRCUIT (DRIVER) . Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E3 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT OPEN (PASSENGER) . Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E4 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT SHORT-CIRCUIT (PASSENGER) .
   • No  : Go to 6. 
6. CHECK DTC. 
   1. Turn the ignition switch to ON.
   2. Turn the temperature control dial at MAX HOT and leave for 16 seconds or more. (For vehicles with left/right independent air conditioner, perform setting on both sides.)
   3. Read the DTC using Subaru Select Monitor. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

   Is DTC B14E1, B14E2, B14E3 or B14E4 displayed?

   • Yes  : Perform the diagnosis for the displayed DTC B14E1, B14E2, B14E3 or B14E4. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E1 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT OPEN (DRIVER) . Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E2 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT SHORT-CIRCUIT (DRIVER) . Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E3 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT OPEN (PASSENGER) . Ref. to AIR CONDITIONER(DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B14E4 AIR MIX DOOR ACTUATOR STEPPING MOTOR CIRCUIT SHORT-CIRCUIT (PASSENGER) .
   • No  : Go to 7. 
7. CHECK EVAPORATOR SENSOR UNIT. 

   Perform the inspection of evaporator sensor unit. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Evaporator Sensor>INSPECTION .

   Is the check result OK?

   • Yes  : Go to 8. 
   • No  : Replace the evaporator sensor. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Evaporator Sensor>REMOVAL .
8. CHECK IN-VEHICLE SENSOR UNIT. 

   Check in-vehicle sensor circuit. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>In-Vehicle Sensor (Auto A/C Model)>INSPECTION . Is the check result OK?

   • Yes  : Go to 9. 
   • No  : Replace the in-vehicle sensor. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>In-Vehicle Sensor (Auto A/C Model)>REMOVAL .
9. CHECK AMBIENT SENSOR UNIT. 

   Check the ambient sensor. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Ambient Sensor>INSPECTION .

   Is the check result OK?

   • Yes  : Go to 10. 
   • No  : Replace the ambient sensor. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Ambient Sensor>REMOVAL .
10. CHECK SUNLOAD SENSOR UNIT. 

    Check the sunload sensor unit. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Sunload Sensor (Auto A/C Model)>INSPECTION .

    Is the check result OK?

    • Yes  : The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis.
      NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
    • No  : Replace the sunload sensor. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Sunload Sensor (Auto A/C Model)>REMOVAL .

*1: For the 75°F center specification. Note that 18 for 25°C center specification and 15 for 22°C center specification.

*2: For the 75°F center specification. Note that 32 for 25°C center specification and 29 for 22°C center specification.