GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 LeSabre 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Defrosting Insufficient

Step

Action

Value(s)

Yes

No

Important: 

   • Excessive moisture in the vehicle could affect system performance, this could be caused by the following conditions:
      - Wet carpet or mats
      - High humidity
      - Interior water leak
      - Blocked A/C evaporator drain tube
      - Maximum passenger occupancy
      - Blocked body relief valves
   • The A/C compressor will not operate (to reduce humidity) in ambient temperatures below 5°C (41°F).

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check

2
  1. Turn ON the ignition, with the engine OFF.
  2. Select DEFROST mode.
  3. Ensure that the defrost outlet on top of the instrument panel is unobstructed.
  4. Adjust blower speed from minimum to maximum.
  5. With a scan tool, observe the Commanded Blower data parameter in the Climate Control Panel data list.

Does the scan tool indicate that the Commanded Blower data parameter is greater than the specified value?

100%

Go to Step 3

Go to Blower Motor Does Not Operate Properly

3
  1. Set blower speed to maximum.
  2. Select DEFROST, DEFOG and PANEL modes.

Does the airflow change discharge locations?

--

Go to Step 4

Go to Air Delivery Improper

4

Important:: Outside air temperature must be above 7°C (45°F).

  1. Start the engine.
  2. Adjust driver side temperature to maximum.
  3. Select DEFROST mode.
  4. Set blower speed to maximum.
  5. Let the engine idle at normal operating temperature.

Does the A/C compressor operate?

--

Go to Step 5

Go to HVAC Compressor Clutch Does Not Engage

5

With a scan tool, observe the ECT data parameter in the powertrain control module data list.

Does the scan tool indicate that the ECT data parameter is within the specified range?

87-98°C

(188-208°F)

Go to Step 6

Go to Symptoms in Engine Cooling

6

Is the defrost airflow warm?

--

Go to Step 7

Go to Heating Insufficient

7

Is the defrost airflow sufficient and is the left defrost airflow similar to the right defrost airflow at the defroster grille and side window outlets?

--

Go to Step 10

Go to Step 8

8
  1. Turn OFF the engine.
  2. Inspect for obstructions and proper defrost duct alignment. Refer to Defroster Grille Replacement in Instrument Panel, Gauges and Console.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 9

9

Inspect the mode door actuator for binding or mechanical failure. Refer to Mode Actuator Replacement .

Did you find and correct the condition?

--

Go to Step 11

Go to Step 10

10
  1. Start the engine.
  2. Verify all the instrument panel outlets are open.
  3. Operate the system. Refer to:

Does the system operate properly?

--

System OK

Go to Symptoms

11

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2