A: EATC System Inoperative, Intermittent, or Improper Operation

A1 CHECK CONTROL DISPLAY

- Ensure engine is cold.
- The In-vehicle temperature should be greater than 10°C (50°F).
- Turn ignition switch to the RUN position.
- Press the AUTOMATIC button.
- Set control at 9O°F (32°C) setting.

- Does control display 90°F (32°C) Auto?

- Yes
Go to A2

- No
Refer to Symptom Charts.

A2 CHECK A/C BLOWER MOTOR OPERATION

- Verify that the A/C blower motor does not come on (Engine coolant temp. is less than 120°F (48°C).

- Does A/C blower motor operate?

- Yes
Refer to General System Diagnosis/Symptom Charts.

- No
Go to A3.

A3 CHECK A/C BLOWER MOTOR OPERATION WITH THE WHEEL FULLY UP

- Ensure that engine is warm (coolant temp. is greater than 120°F (48°C).
- Set control at 75 setting.

- Does A/C blower motor operate?

- Yes
Go to A4.

- No
Refer to A/C Blower Motor Speed Control Diagnosis-Heater Blower Motor Does Not Run At Any Speed under General System Diagnosis/Symptom Charts.

A4 CHECK A/C BLOWER MOTOR SPEED WITH THUMBWHEEL FULLY DOWN

- Rotate blower thumbwheel fully down.

- Does A/C blower motor go to low speed?

- Yes
Go to A5.

- No
Refer to A/C Blower Motor Speed Control Diagnosis-No MEDIUM or LOW Heater Blower Motor Speeds under General System Diagnosis/Symptom Charts.

A5 CHECK A/C BLOWER MOTOR SPEED WITH THUMBWHEEL FULLY UP

- Rotate blower thumbwheel fully up.

- Does A/C blower motor go to high speed?

- Yes
Go to A6.

- No
Refer to A/C Blower Motor Speed Control Diagnosis-No HIGH Heater Blower Motor Speed under General System Diagnosis/Symptom Charts.

A6 CHECK DEFROSTER AND DEMISTER AIR FLOW

- Press the DEFROST button.
- Verify that air is discharged from windshield defroster hose nozzles with small bleed through the side window demister and hoses.
Verify that the heater and A/C air inlet duct door is in the outside air position.

- Are these conditions met?

- Yes
Go to A7.

- No
Refer to General System Diagnosis/Leak Tests/Vacuum Leak Diagnosis.

A7 CHECK AIR FLOW FROM FLOOR DUCT

- Press the FLOOR button.
- Verify that the air is discharged through the heater outlet floor ducts.

- Is this condition met?

- Yes
Go to A8.

- No
Refer to General System Diagnosis/Leak Tests/Vacuum Leak Diagnosis.

A8 CHECK AIR FLOW FROM PANEL REGISTERS

- Press the VENT button.
- Verify that the air is discharged through the panel A/C registers.

- Is this condition met?

- Yes
Go to A9.

- No
Refer to General System Diagnosis/Leak Tests/Vacuum Leak Diagnosis.

A9 CHECK THAT INLET DUCT DOOR IS IN RECIRC POSITION

- Make sure that the ambient temperature is greater than 40°F.
- Press the MAX A/C button.
- Verify that the heater and A/C air inlet duct door is in the recirc position.

- Is this condition met?

- Yes
Go to A1O.

- No
Refer to General System Diagnosis/Leak Tests/Vacuum Leak Diagnosis.

A10 CHECK VENT DISPLAY AND A/C CLUTCH

- Press the VENT button.
- Verify that the VENT display is lit.
- Verify that the A/C clutch is off.

- Are these conditions met?

- Yes
Go to A11.

- No
Refer to A/C Clutch Does Not Disengage When In OFF Diagnosis under General System Diagnosis/Symptom Charts.

A11 CHECK MAX A/C DISPLAY AND A/C CLUTCH

- Press the MAX A/C button again.
- Verify that the MAX A/C display is lit and that the A/C clutch is on.

- Are these conditions met?

- Yes
Go to A12.

- No
Refer to No A/C Clutch Operation Diagnosis under General System Diagnosis/Symptom Charts.

A12 CHECK VFDS

- Press AUTOMATIC button.
- AUTOMATIC or function and fan VFDs should light.

- Do they light?

- Yes
Test complete.

- No
Refer to Diagnosis When Self-Test and Functional Test Indicate No Errors Found under General System Diagnosis/Symptom Charts.