Test Description

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

12: The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Too Cold in Vehicle

Step	Action	Values	Yes	No
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The temperature cannot be adjusted, or the heating is insufficient.
1	IMPORTANT: Both the left and the right air temperature controls are diagnosed in this table. Did you perform the HVAC Diagnostic System Check?	-	Go to Step 2	Go to Diagnostic System Check - HVAC Systems - Manual
2	Turn ON the ignition, with the engine OFF. Place the blower motor switch in each speed position. Does the blower motor operate in any of the speed positions?	-	Go to Step 3	Go to Blower Motor Inoperative
3	Does the blower motor operate in each speed position?	-	Go to Step 4	Go to Blower Motor Malfunction
4	Except for the blower motor speed, are all of the functions of the HVAC control module inoperative?	-	Go to Step 13	Go to Step 5
5	Inspect the cooling system for the following conditions: A low coolant level A loose or worn accessory drive belt A leaking radiator hose or heater hoses A kinked radiator hose or heater hoses A missing radiator cap pressure seal A leaking radiator cap Did you find and correct the condition?	-	Go to Step 22	Go to Step 6
6	Start the engine. Place the blower switch in the OFF position. Place the A/C request switch in the OFF position. Does the A/C compressor operate?	-	Go to HVAC Compressor Clutch Does Not Disengage	Go to Step 7
7	Observe the drive shaft to the air temperature actuator. Adjust the air temperature switch. Does the drive shaft of the air temperature actuator rotate?	-	Go to Step 8	Go to Step 9
8	Inspect the air temperature door and the air temperature actuator for the following conditions: A misaligned air temperature actuator-Refer to Air Temperature Actuator Replacement . Broken or binding linkages or air temperature door An obstruction that prevents the air temperature door from operating within the full range of motion Missing seals to the air temperature door Misaligned seals to the air temperature door Did you find and correct the condition?	-	Go to Step 22	Go to Heating Performance Diagnostic
9	Test the ignition 3 voltage circuit of the air temperature actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 10
10	Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 11
11	Test the door control circuit of the air temperature actuator for an open, a high resistance, a short to ground, or a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 12
12	IMPORTANT: Ensure that the HVAC control module connector is connected during this step in order to avoid misdiagnosis. Turn ON the ignition, with the engine OFF. Measure the voltage from the door control circuit of the air temperature actuator to a good ground. Place the air temperature switch from the coldest position to the warmest position. Is the voltage measurement within the specified values with a smooth transition between cold and hot?	0 V at cold 12 V at hot	Go to Step 17	Go to Step 19
13	Test the ignition 3 voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 14
14	Test the battery positive voltage circuit of the HVAC control module for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 15
15	Test the blower motor control OFF circuit of the HVAC control module for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 16
16	Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 19
17	Inspect for poor connections at the harness connector of the air temperature actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 22	Go to Step 18
18	Inspect the air temperature actuator, door and any attaching linkage for binding or a condition that prevents drive shaft rotation. Did you find and correct the condition?	-	Go to Step 22	Go to Step 20
19	Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 22	Go to Step 21
20	Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement - Right or to Air Temperature Actuator Replacement - Left . Did you complete the replacement?	-	Go to Step 22	-
21	Replace the HVAC control module. Refer to HVAC Control Module Replacement (Buick) or HVAC Control Module Replacement (Pontiac) . Did you complete the replacement?	-	Go to Step 22	-
22	Operate the system in order to verify the repair. Did you correct the condition?	-	System OK	Go to Step 2