This is my first winter with my C5...a 2001.

The temperature was in the high 40's today, and all I get is the blower pushing cool air under the dashboard.

Any thoughts on how to begin to diagnose the problem? I have read in this forum that the HVAC system is mostly electronic. Where do I start?

 

What's your coolant temp reading? Maybe the thermostat is stuck open or removed.

 

Do you have auto or manual AC?

 

Check for codes. With ignition on press and hold options button while pressing and releasing the fuel button four times. The DIC will list the codes.

 

Put it on defrost only and see if it blow hot air. If so, that helps to eliminate a lot. Is it the automatic with 2 zone version?

 

Here is the Shop Manual for the Manual System:

Document ID# 759919
2001 Chevrolet/Geo Corvette


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Too Cold in Vehicle
Test Description
The number below refers to the step number on the diagnostic table.

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

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
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 mode switch in upper, bi-level or defrost position.
Place the blower control in each speed position.
Does the blower motor operate at all?
--
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
Place the mode switch in the vent position.
Place the blower motor switch in the maximum speed position.
Place the outside air switch in the ON position.
Place the recirculation switch in the ON position.
Does the recirculation door operate properly?
--
Go to Step 5
Go to Air Recirculation Malfunction

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 hose
A kinked radiator hose or heater hose
A missing radiator cap pressure seal
A leaking radiator cap
Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?
--
Go to Step 18
Go to Step 6

6
Start the engine.
Place the mode switch in the OFF, VENT or HEAT positions.
Does the A/C compressor operate?
--
Go to HVAC Compressor Clutch Does Not Disengage
Go to Step 7

7
Observe the drive shaft of the air temperature actuator.
Adjust the air temperature switch.
Does the air temperature actuator drive shaft rotate at all?
--
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 its 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 18
Go to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning

9
Test the ignition 3 voltage circuit of the air temperature actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 18
Go to Step 10

10
Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 18
Go to Step 11

11
Test the air temperature door position signal circuit of the air temperature 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?
--
Go to Step 18
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.
Disconnect the air temperature actuator.
Measure the voltage from the air temperature door position signal circuit of the air temperature actuator to a good ground.
Place the air temperature switch from the coldest position to the warmest position.
Does the voltage measure within the specified values with a smooth transition between cold and hot?
12 V at cold 0 V at hot
Go to Step 13
Go to Step 15

13
Inspect for poor connections at the harness connector of the air temperature actuator. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 18
Go to Step 14

14
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 its 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 18
Go to Step 16

15
Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 18
Go to Step 17

16
Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement .

Did you complete the replacement?
--
Go to Step 18
--

17
Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?
--
Go to Step 18
--

18
Operate the system in order to verify the repair.

Did you correct the condition?
--
System OK
Go to Step 2



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Here is the diagnosis for the Automatic HVAC System from the Shop Manual:

Document ID# 759897
2001 Chevrolet/Geo Corvette


--------------------------------------------------------------------------------

Too Cold in Vehicle
Test Description
The numbers below refer to the numbers on the diagnostic table.

This step clears the HVAC control module memory and checks for current air temperature actuator diagnostic trouble codes.

This step checks for A/C compressor clutch always on.

This test is to insure cooling system is operating normally.

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
Did you perform the HVAC Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - HVAC Systems - Automatic

2
Recalibrate actuators. Refer to Re-Calibrating Actuators .
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Observe the Diagnostic Trouble Code (DTC) List in Heating and Air Conditioning.
Does the scan tool display any DTC B0361, B0363, B0365, B0367, B0441 or B0446?
--
Go to Diagnostic Trouble Code (DTC) List
Go to Step 3

3

Important
Ambient air temperature must be above 3°C (38°F).


Start the engine.
Turn OFF the HVAC controls.
Does the A/C compressor operate?
--
Go to HVAC Compressor Clutch Does Not Disengage
Go to Step 4

4
Place the blower motor switch in each speed position.

Does the blower motor operate in each speed position?
--
Go to Step 5
Go to Blower Motor Inoperative

5
Does the blower motor provide sufficient air flow?
--
Go to Step 6
Go to Blower Motor Malfunction

6
Place the blower motor switch in the maximum speed position.
Place the mode switch in the bi-level position.
Place the outside air switch in the ON position.
Place the recirculation switch in the ON position.
Does the recirculation door operate properly?
--
Go to Step 7
Go to Air Recirculation Malfunction

7
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 hose
A kinked radiator hose or heater hose
A missing radiator cap pressure seal
A leaking radiator cap
Did you find and correct the condition?
--
Go to Step 20
Go to Step 8

8
Install a thermometer near the inside air temperature sensor.
With a scan tool, observe the Inside Temp Sensor data parameters in the Heating and Air Conditioning data list.
Does the scan tool indicate that the sensor temperatures are within 3°C (5°F) of the thermometer temperatures?
--
Go to Step 10
Go to Step 9

9
Inspect for a blocked, malfunctioning, or incorrectly installed inside air temperature sensor. Refer to Inside Air Temperature Sensor Replacement .

Did you find and correct the condition?
--
Go to Step 20
Go to Step 13

10
Turn the engine OFF.
Install a scan tool.
Cover the sunload sensor.
Start the engine.
Adjust driver side temperature to 22°C (72°F).
With a scan tool, observe the Sun Load Sensor data parameter in the Heating and Air Conditioning data list.
Does the scan tool indicate that the Sunload Sensor parameter is greater than the specified value?
4.3 V
Go to Step 11
Go to Step 15

11
Uncover the sunload sensor.
Direct a light source at the sunload sensor.
Does the voltage change?
--
Go to Step 12
Go to Step 15

12
Perform the Heating Performance Diagnostic. Refer to Heating Performance Diagnostic in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?
--
Go to Step 20
System OK

13
Inspect for poor connections at the harness connector of the inside air temperature sensor. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 20
Go to Step 14

14
Turn OFF the ignition.
Test the inside air temperature sensor resistance. Refer to Sensor Resistance Table .
Does the resistance measure near the specified value?
--
Go to Step 16
Go to Step 17

15
Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 20
Go to Step 18

16
Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 20
Go to Step 19

17
Replace the inside air temperature sensor. Refer to Inside Air Temperature Sensor Replacement .

Did you complete the replacement?
--
Go to Step 20
--

18
Replace the sunload sensor. Refer to Sun Load Sensor Replacement .

Did you complete the replacement?
--
Go to Step 20
--

19

Important
Perform the recalibration procedure for the HVAC control module.


Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?
--
Go to Step 20
--

20
Operate the system in order to verify the repair.

Did you correct the condition?
--
System OK
Go to Step 3

 

I'm having the same problem. Are there any simpler solutions the the above?

Thanks,

Clayton from Las Vegas

 

Yeah, you could have someone else actually troublshoot and fix it for you......

 

Clayton...It could be a faulty outside air temp sensor. GM Part #10248414 AMB AIR Sensor

It is $10 from the dealer and just plugs in.

The sensor is located on the right (passenger) side of the car, on the outside of the frame rail in the very front by the headlight.

It is held onto the mounting hole on the frame by a plastic push-in clip.

Just pull the clip out of the hole on the frame, release the plug for the wire (the plug has a release clip, pry up on the clip and the plug will release).

Then just put in the new one - it takes a few minutes of driving for the sensor to start reading the outside temp - you have to be moving.

The sensors are either resistance temperature detectors (RTD's) or Thermistors. The resistance of the sensor changes with the temperature.
If you have any corrosion in any of the associated connectors. it will increase the resistance that the climate controls is reading.
The resistance across the two sensor wires could be almost infinity.