Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001H97X
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 09/2022]
Title: HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for HV Model): Weak Blower Output; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

Weak Blower Output

DESCRIPTION

If the airflow from the front registers is weak regardless of the blower speed setting displayed on the air conditioning control assembly, the following factors may be the cause.

Symptom

Factor
  • Airflow volume is constantly low
  • Airflow volume sometimes becomes low
  • Blower motor with fan sub-assembly malfunction
  • ECO mode control of air conditioning system is enabled
  • Clogged clean air filter
  • Clogged No. 1 cooler evaporator sub-assembly or heater radiator unit sub-assembly fins
  • No. 1 cooler thermistor malfunction
  • Aspirator not connected properly

PROCEDURE

1.

CHECK AIR CONDITIONING SYSTEM

(a) Operate the blower switch with the following conditions met and check that the airflow volume changes.

Blower Speed

Condition

LO → HI
  • Temperature setting: MAX COLD
  • Air outlet mode: FACE
  • A/C switch: Off

OK:

Airflow volume increases.

NG

GO TO OTHER DIAGNOSIS PROCEDURE (Blower Motor Circuit)

OK

2.

CHECK ECO MODE SETTING

(a) Check if the ECO mode indicator is off.

OK:

The ECO mode indicator is off.

NG

GO TO STEP 4

OK

3.

CHECK ECO MODE CONTROL OPERATION

(a) Operate the ECO switch assembly (air conditioning control assembly) and check that the ECO mode indicator turns off and the blower speed reduction is canceled.

HINT:

  • When ECO mode control is operating, the air conditioning amplifier assembly controls the air conditioning system to enhance fuel efficiency. Therefore, explain to the customer that, when ECO mode control is operating, the blower speed will be reduced.

    Control

    Outline

    Blower Control

    When the air conditioning system is in AUTO mode, the blower speed will be reduced to a certain speed. Additionally, if warm-up control is operating, the blower speed will be further reduced.

    Air Inlet Control

    If the ambient temperature is a certain value or more, the air inlet mode will be changed to recirculation mode.
  • In some situations, ECO mode control may not operate even though it is enabled.

Result

Proceed to

ECO mode indicator turns off and blower speed reduction is canceled

A

ECO mode indicator turns off, but the blower speed reduction is not canceled

B

ECO mode indicator does not turn off

C
B

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

C

REPLACE AIR CONDITIONING CONTROL ASSEMBLY

A

4.

CHECK CLEAN AIR FILTER

(a) Visually check the clean air filter.

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OK:

The clean air filter is not dirty or clogged.

NG

REPLACE CLEAN AIR FILTER

OK

5.

CHECK NO. 1 COOLER THERMISTOR

(a) Check the installation condition of the No. 1 cooler thermistor.

OK:

The No. 1 cooler thermistor is installed correctly.

NG

INSTALL NO. 1 COOLER THERMISTOR

OK

6.

CHECK ASPIRATOR

(a) Check the installation condition of the aspirator.

OK:

The aspirator is installed correctly.

OK

REPLACE HEATER RADIATOR UNIT SUB-ASSEMBLY OR NO. 1 COOLER EVAPORATOR SUB-ASSEMBLY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; HEATING / AIR CONDITIONING: AIR CONDITIONING UNIT: REMOVAL 2020 - 2021 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 06/2021]; HEATING / AIR CONDITIONING: AIR CONDITIONING UNIT: REMOVAL 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2021 - 09/2022]; HEATING / AIR CONDITIONING: AIR CONDITIONING UNIT: REMOVAL

NG

INSTALL ASPIRATOR 2020 - 2021 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 06/2020]; HEATING / AIR CONDITIONING: AIR CONDITIONING UNIT: REASSEMBLY 2021 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2020 - 09/2022]; HEATING / AIR CONDITIONING: AIR CONDITIONING UNIT: REASSEMBLY