Compartment Temperature Is Excessively Lower Than Setting Temperature

WARNING: This page is about a different variant/trim than selected.

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 (without humidity sensor)
Temperature and humidity sensor failure (with humidity sensor)
Ambient temperature sensor failure
Sunload sensor failure

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> GENERAL DESCRIPTION> CAUTION .

CHECK AIRFLOW CAPACITY .
Check the airflow capacity. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTICS WITH PHENOMENON>INSPECTION>AIR GOES OUT OF CONTROL (BLOWER MOTOR ROTATES AT HIGH SPEED) .

Is the check result OK?

Yes: Go to 2.

No: Perform repair according to inspection procedure.
CHECK AMOUNT OF REFRIGERANT PRESSURE .
Check the refrigerant pressure. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET .

Is the check result OK?

Yes: Go to 3.

No: Perform repair according to refrigerant pressure inspection.
CHECK A/C CONTROL PANEL .
1. Turn the ignition switch to ON.
2. Turn the temperature control dials (driver's side) and (passenger's side) to MAX COOL.
3. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Air Conditioner] Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)>DATA MONITOR .
  - Heater Control Panel Setting Value (Driver's)
  - Heater Control Panel Setting Value (Passenger's)
  Po [Heater Control Panel Setting Value (Driver's)] and [Heater Control Panel Setting Value (Passenger's)] indicate "59"*1?
  
  (*1: For the 72°F center specification. 17.5 for the 25°C center specification.)
  
  Yes: Go to 4.
  
  No: Replace the A/C control panel. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> CONTROL PANEL .
CHECK A/C CONTROL PANEL .
1. Turn the temperature control dials (driver's side) and (passenger's side) to MAX HOT.
2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Air Conditioner]. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> 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 "86"*2?
  
  (*2: For the 72°F center specification. 32.5 for the 25°C center specification.)
  
  Yes: Go to 5.
  
  No: Replace the A/C control panel Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> CONTROL PANEL .
CHECK DTC .
1. 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.)
2. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> DIAGNOSTIC TROUBLE CODE (DTC) .
  Is DTC B1440, B1442, B1446, B1436, B1437 or B1441 displayed? (Current malfunction)
  
  Yes: Perform the diagnosis for DTC B1440, B1442, B1446, B1436, B1437 or B1441.
  
  No: Go to 6.
CHECK DTC .
1. 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.)
2. Read the DTC of [Air Conditioner] using the Subaru Select Monitor Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> DIAGNOSTIC TROUBLE CODE (DTC) .
  Is DTC B1440, B1442, B1446, B1436, B1437 or B1441 displayed? (Current malfunction)
  
  Yes: Perform the diagnosis for DTC B1440, B1442, B1446, B1436, B1437 or B1441.
  
  No: Go to 7.
CHECK EVAPORATOR SENSOR UNIT .
Perform the inspection of evaporator sensor unit Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> EVAPORATOR SENSOR .

Is the check result OK?

Yes: Go to 8.

No: Replace the evaporator sensor. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> EVAPORATOR .
CHECK IN-VEHICLE SENSOR OR TEMPERATURE AND HUMIDITY SENSOR UNIT .
Check the in-vehicle sensor (without humidity sensor) or temperature and humidity sensor (with humidity sensor). Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> IN-VEHICLE SENSOR (AUTO A/C MODEL) . Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> TEMPERATURE AND HUMIDITY SENSOR .

Is the check result OK?

Yes: Go to 9.

No: Replace the in-vehicle sensor (without humidity sensor) or temperature and humidity sensor (with humidity sensor). Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> IN-VEHICLE SENSOR (AUTO A/C MODEL) . Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> TEMPERATURE AND HUMIDITY SENSOR .
CHECK AMBIENT SENSOR UNIT .
Check the ambient sensor. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> AMBIENT SENSOR .

Is the check result OK?

Yes: Go to 10.

No: Replace the ambient sensor. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> AMBIENT SENSOR .
CHECK SUNLOAD SENSOR UNIT .
Check the sunload sensor unit. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)>SUNLOAD SENSOR (AUTO A/C MODEL) .

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 again.

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 AIR CONDITIONER (EXCEPT FOR HEV)>SUNLOAD SENSOR (AUTO A/C MODEL) .