d1nonly34

Ok Ive done some research and for the automatic climate control there are three sensors. 1- Ambient sensor 2- In car senosr 3- Sunload senosr. Can anyone tell me what these exact sensors do and where they are located?

Also, this maybe a long shot but since I switched my manual a/c to digital I am not able to change temperatures it just stays on cold. Does anyone know why? Thanks.

in2pro

Im going to go with:

1- Ambient sensor = sensors located in front of vehicle behind grill

2- In car senosr = the sensor right above the drivers head

3- Sunload senosr = the sensor located in the center of the dash

d1nonly34

thanks that really helped... do you happen to know the specific functions of each? im asking because for sure the sunload sensor has to be changed because it has 4 cables going into it where my old one only had two. I'm wondering if these sensors have any effect on the digital a/c system and wether i might need to changed the harnesses for each also.

73shark

The digital A/C requires the in-car sensor that's located to the left of the driver's head and looks like a small speaker.

shawnvw

Air Temperature Sensor

The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:
•
Ambient Air Temperature Sensor [align=left]•
Inside Air Temperature Sensor Assembly [/align][align=left]•
Upper Left Air Temperature Sensor [/align][align=left]•
Upper Right Air Temperature Sensor [/align][align=left]•
Lower Left Air Temperature Sensor [/align][align=left]•
Lower Right Air Temperature Sensor [/align][align=left]•
Upper Air Temperature Sensor - Auxiliary [/align][align=left]•
Lower Air Temperature Sensor - Auxiliary [/align]
A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 to +101°C (-40 to +215°F). The sensor signal varies between 0-5volts.
The input of the duct air temperature sensors are different from the ambient and inside air temperature sensors. The HVAC control module converts the signal to a range between 0-255counts. As the air temperature increases the count value will decrease. If the HVAC control module or auxiliary HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted air temperature value. The default value for the ambient and inside air temperature sensors will be displayed on the scan tool. The default value for the duct air temperature sensors will not be displayed on the scan tool. The scan tool parameter for the duct air temperature sensors are the actual state of the signal circuit. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.
The ambient air temperature sensor mounts underhood and can be affected by city traffic, by idling, and by restarting a hot engine. Therefore, the HVAC control module filters the value of the ambient air temperature sensor for temperature display. The ambient air temperature value is updated under the following conditions:

Condition

Display

At start up with the engine off less than 2hours
Displays last stored temperature

At start up with the engine off more than 2hours
Displays real-time temperature

Engine coolant temperature is less than 28°C (50°F) above the ambient air temperature
Displays real-time temperature

Vehicle speed above 32km/h (20mph) for a minimum of 80seconds
Displays real-time temperature

Vehicle speed above 72km/h (45mph)
Displays real-time temperature

Sensor reading is less than the last displayed value
Displays real-time temperature

The scan tool has the ability to update the displayed ambient air temperature. To update the ambient air temperature display on the HVAC control module, perform the following procedure: Turn ON the ignition. Simultaneously press the A/C and Recirc switches for 5 seconds



Sunload Sensor Assembly

The sunload sensor is a 2-wire photo diode. The vehicle uses left and right sunload sensors. The 2sensors are integrated into the sunload sensor assembly. Low reference and signal circuits enable the sensor to operate. As the light shining upon the sensor gets brighter, the sensor resistance increases. The sensor signal decreases as the resistance increases. The sensor operates within an intensity range between completely dark and bright. The sensor signal varies between 0-5volts. The HVAC control module converts the signal to a range between 0-255counts. The sunload sensor provides the HVAC control module a measurement of the amount of light shining on the vehicle. Bright, or high intensity, light causes the vehicles inside temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle. If the HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted sunload value. This value will not be displayed on the scan tool. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is fixed. The scan tool parameter for the sunload sensor is the actual state of the signal circuit.

d1nonly34

wow that was a GREAT explanation! I really appreciate it, it makes one appreciate what the smallest of things can do. So by reading this I assume there are about 11 sensors in total (not including the in-car sensor that is located above the drivers head). I found this diagram from a chevy parts website that shows the air temp sensors in the front, does this look correct? They dont differentiate wether it is an automatic climate control system or not, does it make a difference or will the sensors work for both systems?

http://www.parts4chevys.com/partloca...layCatalogid=0


Going through the website I noticed they have several in car sensors and different ambient sensors. The ambient sensor thatyou described which is underhood, would that have to be changed also? My temperature gauge on my rear view mirrow works fine. And finally the sunload sensor, I just want to be clear, you said there are 2 sensors (left and right) but that they are integrated into the sunload sensor assembly... does this mean that there are two sensors in one in that little black "thing" in the middle top duct panel near the front windshield? I ask because on my other dash the sensor only had two wires going into it and the new dash came with a 4 wire harness but didnt bring the sensor. Just trying to clarify that and not that there are 2 sensors one on the left side and one on the opposite side. Thanks for your help!

d1nonly34

One more thing, right now I am missing the in-car sensor (above the head) and sunload sensor (near windshield). By attaining these sensors will the digital a/c finally work correctly? By correctly I mean being able to change temperature from hot to cold rather than only cold always no matter what temperature I have on the display.

shawnvw

Jusy so you don't get the wrong impression, I didn't write that. I copy\pasted it from a gm website. It says "The 2sensors are integrated into the sunload sensor assembly". The way I understand that is that the sensor assembly has 2 sunload sensors in it, which it why you have 4 wires.

As for the questions of will the temp sensor work in both systems....the manual system does not have any temp sensors. It just blasts air at you at the speed you choose, and at the temp you set it at. The automatic system allows you to set the temp, and let the unit do the rest. It reads the cabin temp, compares it to the temp coming out of the vents and adjusts the blend doors and fan speeds accordingly
It LOOKS as though the sensors you have the diagram are the correct ones.

Adding all the sensors may or may not bring that climate controls to life. Either way, if you want them to work, getting all the sensors is the first step to getting to firgured out. I'll post wiring diagrams below of both manual and auto systems so you can be sure that all inputs are present.

shawnvw

MANUAL SYSTEM


HVAC Control Module C1

Connector Part Information[*]OEM: 15491305[*]Service: 15126709[*]Description: 20-Way F USCAR 0.64 Series (BN)
[ul][/ul]
Terminal Part Information[*]Terminal/Tray: SAITS-A03T-M064/14[*]Core/Insulation Crimp: P/P[*]Release Tool/Test Probe: J-38125-215/J-35616-64B (L-BU)
[ul][/ul]HVAC Control Module C1

Pin
Wire Color
Circuit No.
Function


1-7
Not Used

8
PK
2145
Air Temperature Switch Signal - Right

9
OG
2615
Auxiliary Mode Door Signal

10
YE
2214
Auxiliary Air Temperature Door Signal

11-17
Not Used

18
GY
2599
Auxiliary Mode Door Position Signal

19
PU/WH
760
Auxiliary Blower Motor Speed Signal

20
Not Used

HVAC Control Module C2

Connector Part Information [*]OEM: 15483873[*]Service: 21997402[*]Description: 16-Way F USCAR 0.64 Series (BU)
[ul][/ul]
Terminal Part Information[*]Terminal/Tray: SAITS-A03T-M064/14[*]Core/Insulation Crimp: P/P[*]Release Tool/Test Probe: J-38125-215/J-35616-64B (L-BU)
[ul][/ul]HVAC Control Module C2

Pin
Wire Color
Circuit No.
Function

1
YE
6817
LED Backlight Dimming Control

2
OG
300
Ignition 3 Voltage

3
BK/WH
1851
Ground

4
RD/WH
3340
Battery Positive Voltage

5
D-GN
5060
Low Speed GMLAN Serial Data

6
D-BU
204
A/C Low Pressure Sensor Signal

7
Not Used

8
WH
193
Rear Defog Relay Control

9
Not Used

10
BK
1050
Ground

11
GY
597
5-Volt Reference

12
D-GN
6101
Low Reference

13-16
Not Used


HVAC Control Module C3


Connector Part Information [*]OEM: 15491304[*]Service: 15126710[*]Description: 20-Way F USCAR 0.64 Series (GY)
[ul][/ul]
Terminal Part Information[*]Terminal/Tray: SAITS-A03T-M064/14[*]Core/Insulation Crimp: P/P[*]Release Tool/Test Probe: J-38125-215/J-35616-64B (L-BU)
[ul][/ul]
HVAC Control Module C3

Pin
Wire Color
Circuit No.
Function

1
Not Used

2
YE/BK
713
Defrost/Heater Mode Valve Position Sensor Signal

3
Not Used

4
GY/BK
754
Blower Motor Speed Control

5-9
Not Used

10
GY
598
5-Volt Reference

11
Not Used

12
L-BU
733
Air Temperature Door Position Signal

13
D-BU
1646
Auxiliary Air Temperature Door Position Signal

14
Not Used

15
TN
2273
Mode Door Control

16
D-BU
1199
Air Temperature Door Control

17
D-GN
1614
Recirculation Door Control

18
WH/BK
1236
Auxiliary Air Temperature Door Control

19
Not Used

20
YE
1791
Low Reference


HVAC Control Module C4


Connector Part Information [*]OEM: 15483874[*]Service: 21997401[*]Description: 16-Way F Kaizen 0.64 Series (GN)
[ul][/ul]
Terminal Part Information[*]Terminal/Tray: SAITS-A03T-M064/14[*]Core/Insulation Crimp: P/P[*]Release Tool/Test Probe: J-38125-215/J-35616-64B (L-BU)
[ul][/ul]HVAC Control Module C4

Pin
Wire Color
Circuit No.
Function

1
Not Used

2
GY
596
5-Volt Reference

3
OG
2215
Auxiliary Mode Door Control

4
GY
2614
Auxiliary Air Temperature Door Control

5
GY/BK
1798
Low Reference

6-9
Not Used

10
D-GN
2211
Auxiliary Blower Motor Speed Control

11-16
Not Used

d1nonly34

I had figured you copied and pasted that. First thing tomorrow I'm going to check my system to see if I have the sensors and whether not there are holes for them. I'm hoping there are holes but more so if there arent then getting wiring for them. I changed my entire front dash but obviously the hvac part stayed there. If you could get me those wiring diagrams that would be a tremendous help.