How do you get the heater to work on a 2003 Chevy venture mini van

When you change the mode from floor to vent to defrost do you hear switching taking place behind the dash or inside ?

Air Delivery Improper

Test Description
The numbers below refer to the step numbers on the diagnostic table.
The measured voltage should be near the specified values for each mode position.
The HVAC control module is supplied by two ignition 3 voltage circuits. Test the ignition 3 voltage circuit that does not supply the blower motor switch.
Step
Action
Value
Yes
No
Schematic Reference: HVAC Schematics
Connector End View Reference: HVAC Connector End Views
DEFINITION: Air does not flow correctly from the air distribution outlets.
1
Did you perform the HVAC Diagnostic System Check?
--
YES - Go to Step 2
NO - Go to Diagnostic System Check - HVAC Systems - Manual
2
Turn ON the ignition, with the engine OFF.
Place the blower motor switch in the OFF position.
Is the blower motor OFF?
--
YES - Go to Step 3
NO - Go to Blower Motor Always On
3
Place the blower motor switch in each speed position.
Does the blower motor operate at all?
--
YES - Go to Step 4
NO - Go to Blower Motor Inoperative
4
Does the blower motor operate in each speed position?

YES - Go to Step 5
NO - Go to Blower Motor Malfunction
5
Except for the blower motor speed, are all of the functions of the HVAC control module inoperative?
--
YES - Go to Step 14
NO - Go to Step 6
6
Place the blower motor switch in the maximum speed position.
Place the mode switch in the vent position.
Place the recirculation switches in the recirculation position and in the outside air position.
Does the recirculation door move to the correct position for each selection?
--
YES - Go to Step 7
NO - Go to Air Recirculation Malfunction
7
Place the blower motor switch in the maximum speed position.
Place the mode switch in each position.
Is the air flow sufficient from the correct outlets in each mode?
--
YES - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
NO - Go to Step 8
8
Inspect the air distribution system for the following conditions:
• A dirty HVAC air filter, if applicable
• An obstruction to the air flow
• Air leaks
• Misaligned air ducts
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 9
9
Inspect the mode door and the mode actuator for the following conditions:
• A misaligned mode actuator
Refer to Mode Actuator Replacement .
• Broken or binding linkages or mode door
• An obstruction that prevents the mode actuator from operating within its full range of motion
• Missing seals to the mode door
• Misaligned seals to the mode door
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 10
10
Turn OFF the ignition.
Disconnect the mode actuator.
Turn ON the ignition, with the engine OFF.
Probe the ignition 3 voltage circuit of the mode actuator with a test lamp that is connected to a good ground.
Does the test lamp illuminate?
--
YES - Go to Step 11
NO - Go to Step 20
11
Test the ground circuit of the mode actuator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 12
12
Measure the voltage from the mode door control circuit of the mode actuator to a good ground.
Place the mode switch in each mode position while observing the voltage.
Does the voltage measure near the specified values for each mode position?
Vent 0.2V, Bi-Level 3.0V, Floor 6.0V, Mix-Blend 9.0V, Defrost 12.0V
YES - Go to Step 18
NO - Go to Step 13
13
Test the mode door control circuit of the mode actuator for an open, high resistance, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 19
14
Test the ignition 3 voltage circuit of the HVAC control module for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 15
15
Test the battery positive voltage circuit of the HVAC control module for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 16
16
Test the ground circuit of the HVAC control module for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 17
17
Test the off blower motor control circuit of the HVAC control module for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 23
NO - Go to Step 19
18
Inspect for poor connections at the harness connector of the mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 23
Go to Step 21
19
Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 23
Go to Step 22
20
Repair the ignition 3 voltage circuit of the mode actuator. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 23
--
21
Replace the mode actuator. Refer to Mode Actuator Replacement .
Did you complete the replacement?
--
Go to Step 23
--
22
Replace the HVAC Control module. Refer to HVAC Control Module Replacement .
Did you complete the replacement?
--
Go to Step 23
--
23
Operate the system in order to verify the repair.
Did you correct the condition?
--
System OK
Go to Step 8