1995 Air Conditioning Dash Control
07-31-2014, 01:11 AM
#1
Intermediate
Thread Starter
Member Since: Jul 2014
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
1995 Air Conditioning Dash Control
Hi All
I have just purchased a 1995 Corvette and I am starting to fix the few things that are wrong with it. Right now I am working on the AC because the compressor clutch does not engage when the AC is turned on. Looking at my Datamaster while turning on the AC tells me that the AC request is not getting sent from the dash controller to the pcm. The first thing I noticed is that my AC Dash controller looks to be from an older car as it has orange writing on the buttons instead of white. I am thinking that the previous owner replaced the dash control with the wrong one. I pulled the dash apart and looked at the part number and it was #16162371 which looks to be for a 92-93 corvette. Do you guys know if the dash controls from a 92-93 would work with the 95 or is this why my ac is not working correctly? Did the 92-93 controller work the same way as far as the ac request to the computer? From the research I have done it seems that my car should actually have part #15-72065 which is the dash control for 94-96.
Thanks!
Ron
I have just purchased a 1995 Corvette and I am starting to fix the few things that are wrong with it. Right now I am working on the AC because the compressor clutch does not engage when the AC is turned on. Looking at my Datamaster while turning on the AC tells me that the AC request is not getting sent from the dash controller to the pcm. The first thing I noticed is that my AC Dash controller looks to be from an older car as it has orange writing on the buttons instead of white. I am thinking that the previous owner replaced the dash control with the wrong one. I pulled the dash apart and looked at the part number and it was #16162371 which looks to be for a 92-93 corvette. Do you guys know if the dash controls from a 92-93 would work with the 95 or is this why my ac is not working correctly? Did the 92-93 controller work the same way as far as the ac request to the computer? From the research I have done it seems that my car should actually have part #15-72065 which is the dash control for 94-96.
Thanks!
Ron
07-31-2014, 03:34 AM
#2
Melting Slicks
Hi All
I have just purchased a 1995 Corvette and I am starting to fix the few things that are wrong with it. Right now I am working on the AC because the compressor clutch does not engage when the AC is turned on. Looking at my Datamaster while turning on the AC tells me that the AC request is not getting sent from the dash controller to the pcm. The first thing I noticed is that my AC Dash controller looks to be from an older car as it has orange writing on the buttons instead of white. I am thinking that the previous owner replaced the dash control with the wrong one. I pulled the dash apart and looked at the part number and it was #16162371 which looks to be for a 92-93 corvette. Do you guys know if the dash controls from a 92-93 would work with the 95 or is this why my ac is not working correctly? Did the 92-93 controller work the same way as far as the ac request to the computer? From the research I have done it seems that my car should actually have part #15-72065 which is the dash control for 94-96.
Thanks!
Ron
I have just purchased a 1995 Corvette and I am starting to fix the few things that are wrong with it. Right now I am working on the AC because the compressor clutch does not engage when the AC is turned on. Looking at my Datamaster while turning on the AC tells me that the AC request is not getting sent from the dash controller to the pcm. The first thing I noticed is that my AC Dash controller looks to be from an older car as it has orange writing on the buttons instead of white. I am thinking that the previous owner replaced the dash control with the wrong one. I pulled the dash apart and looked at the part number and it was #16162371 which looks to be for a 92-93 corvette. Do you guys know if the dash controls from a 92-93 would work with the 95 or is this why my ac is not working correctly? Did the 92-93 controller work the same way as far as the ac request to the computer? From the research I have done it seems that my car should actually have part #15-72065 which is the dash control for 94-96.
Thanks!
Ron
Batee is the guru for dash and climate controller issues, have a look on his website and you may be able to fix it yourself.
http://www.batee.com/corvette/acrepair/c68/
07-31-2014, 03:06 PM
#3
Intermediate
Thread Starter
Member Since: Jul 2014
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
Hi
Batee is the guru for dash and climate controller issues, have a look on his website and you may be able to fix it yourself.
http://www.batee.com/corvette/acrepair/c68/
Batee is the guru for dash and climate controller issues, have a look on his website and you may be able to fix it yourself.
http://www.batee.com/corvette/acrepair/c68/
07-31-2014, 05:15 PM
#4
Melting Slicks
Member Since: Aug 1999
Location: Baltimore, MD USA
Posts: 2,240
Likes: 0
Received 34 Likes
on
30 Posts
If pressing the three buttons listed below and no AC request shows
on your scanner either the HVAC control head is not compatible or
the Low Pressure cycling switch is open due to low refrigerant.
(Less than 47 psi).
Turn the ignition On
When you push the Max/AC, Normal/AC or Bi-level button a ground
is placed on the Dark Blue wire at the AC Low pressure cycling
switch which is screwed into the Evaporator pipe on the outside of
the evaporator box. Use a meter and verify that is happening.
When you press the Off button you should measure less than 12 volts on either the Dark Green/White or Dark Blue wire.
The ground signal passes thru the switch and to a Dark Green/White wire which goes to the PCM Black connector pin 1.
This is the AC Request signal.
Using your scanner software you should be able to read the feed back voltage
from the Ac High Pressure sensor. Needs to be greater than .12 volts and less than 4.86
volts DC.
on your scanner either the HVAC control head is not compatible or
the Low Pressure cycling switch is open due to low refrigerant.
(Less than 47 psi).
Turn the ignition On
When you push the Max/AC, Normal/AC or Bi-level button a ground
is placed on the Dark Blue wire at the AC Low pressure cycling
switch which is screwed into the Evaporator pipe on the outside of
the evaporator box. Use a meter and verify that is happening.
When you press the Off button you should measure less than 12 volts on either the Dark Green/White or Dark Blue wire.
The ground signal passes thru the switch and to a Dark Green/White wire which goes to the PCM Black connector pin 1.
This is the AC Request signal.
Using your scanner software you should be able to read the feed back voltage
from the Ac High Pressure sensor. Needs to be greater than .12 volts and less than 4.86
volts DC.
Last edited by Hooked on Vettes; 07-31-2014 at 05:18 PM.
08-01-2014, 12:33 AM
#5
Drifting
Member Since: Nov 2013
Location: Loud, Raw and Dangerous 1968 327 4S in Southern California
Posts: 1,313
Received 387 Likes
on
278 Posts
FYI...I was having trouble with my HVAC system on my 94 and was able to buy a replacement control module (the one above the radio) on Ebay for $100. Easy to put in and worked great...was worth the risk.
08-01-2014, 12:50 AM
#6
Intermediate
Thread Starter
Member Since: Jul 2014
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
If pressing the three buttons listed below and no AC request shows
on your scanner either the HVAC control head is not compatible or
the Low Pressure cycling switch is open due to low refrigerant.
(Less than 47 psi).
Turn the ignition On
When you push the Max/AC, Normal/AC or Bi-level button a ground
is placed on the Dark Blue wire at the AC Low pressure cycling
switch which is screwed into the Evaporator pipe on the outside of
the evaporator box. Use a meter and verify that is happening.
When you press the Off button you should measure less than 12 volts on either the Dark Green/White or Dark Blue wire.
The ground signal passes thru the switch and to a Dark Green/White wire which goes to the PCM Black connector pin 1.
This is the AC Request signal.
Using your scanner software you should be able to read the feed back voltage
from the Ac High Pressure sensor. Needs to be greater than .12 volts and less than 4.86
volts DC.
on your scanner either the HVAC control head is not compatible or
the Low Pressure cycling switch is open due to low refrigerant.
(Less than 47 psi).
Turn the ignition On
When you push the Max/AC, Normal/AC or Bi-level button a ground
is placed on the Dark Blue wire at the AC Low pressure cycling
switch which is screwed into the Evaporator pipe on the outside of
the evaporator box. Use a meter and verify that is happening.
When you press the Off button you should measure less than 12 volts on either the Dark Green/White or Dark Blue wire.
The ground signal passes thru the switch and to a Dark Green/White wire which goes to the PCM Black connector pin 1.
This is the AC Request signal.
Using your scanner software you should be able to read the feed back voltage
from the Ac High Pressure sensor. Needs to be greater than .12 volts and less than 4.86
volts DC.
Hey, thanks for the great information. I also have the Factory service manual for the car and so far I ran through the Chart C-10 on page 6E3-C10-5. I found that if I jumped voltage to the DK BLU wire (B2) at the AC control unit harness I did see the AC Request on my scan tool. I think this means the Control unit is bad as the ground at (B8) is good and the Voltage at (A1) is also good. However I am confused as the description at Chart C-10 says voltage is applied to the A/C request signal line from the control unit... however on page 8A the description under HVAC Compressor control says it applies ground like in your description... According to the Chart C-10 that I followed it should be voltage applied and that seemed to work to get my AC Request. What are your thoughts? I have added scans of the two different pages.
Thanks!
Ron
08-01-2014, 11:20 AM
#7
Melting Slicks
Member Since: Aug 1999
Location: Baltimore, MD USA
Posts: 2,240
Likes: 0
Received 34 Likes
on
30 Posts
First question is your 95 a ZR1?
I'm looking at the 95 Helms Red two book set of Service manuals. (White colored front page are the Preliminary manuals).
The Chart 6E3-C10-5 is for a Vin J which is the ZR1.
I assumed you have a Vin P which is the LT1.
Looking at the schematic, if you jumped 12 volts to B2 the Dark Blue wire and the controls were in Max, Normal or Bi-Level the 12 volts should have been shorted to ground.
For C68 Auto climate control the manual says the AC request is 12 volts. (Which I believe is wrong).
For C60 Manual climate control the manual says the AC request is a ground signal (zero volts which I believe is correct).
What I notice is both AC request signals go to the PCM Black connector Pin 1.
For the C60 AC request signal at the PCM they show an Ignition voltage and a pull up resistor in the PCM block diagram. This would indicate to me when the circuit is open there is at least 12 volts at the open resistor end.
When the AC request ground signal is at Pin 1 of the PCM the open end of the resistor is now at ground level. (zero volts).
The C68 shows no pull up resistor for the AC Request signal in the PCM.
Obviously since the C60 and C68 both input to the PCM the AC Request single on the same pin 1 the signal can only be a 12 volts or Zero volts. So the description in the manual must be wrong for C68.
**************************************** **************************************** *****************
I would measure the Dark Blue wire and verify what the voltage is when you request AC and when the unit is Off.
If you placed 12 volts on the Dark Blue wire you said the scanner showed the AC Request signal, did the compressor clutch engage?
I'm looking at the 95 Helms Red two book set of Service manuals. (White colored front page are the Preliminary manuals).
The Chart 6E3-C10-5 is for a Vin J which is the ZR1.
I assumed you have a Vin P which is the LT1.
For C68 Auto climate control the manual says the AC request is 12 volts. (Which I believe is wrong).
For C60 Manual climate control the manual says the AC request is a ground signal (zero volts which I believe is correct).
What I notice is both AC request signals go to the PCM Black connector Pin 1.
For the C60 AC request signal at the PCM they show an Ignition voltage and a pull up resistor in the PCM block diagram. This would indicate to me when the circuit is open there is at least 12 volts at the open resistor end.
When the AC request ground signal is at Pin 1 of the PCM the open end of the resistor is now at ground level. (zero volts).
The C68 shows no pull up resistor for the AC Request signal in the PCM.
**************************************** **************************************** *****************
I would measure the Dark Blue wire and verify what the voltage is when you request AC and when the unit is Off.
If you placed 12 volts on the Dark Blue wire you said the scanner showed the AC Request signal, did the compressor clutch engage?
Last edited by Hooked on Vettes; 08-01-2014 at 12:57 PM.
08-01-2014, 09:30 PM
#8
Intermediate
Thread Starter
Member Since: Jul 2014
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
First question is your 95 a ZR1?
I'm looking at the 95 Helms Red two book set of Service manuals. (White colored front page are the Preliminary manuals).
The Chart 6E3-C10-5 is for a Vin J which is the ZR1.
I assumed you have a Vin P which is the LT1.
Looking at the schematic, if you jumped 12 volts to B2 the Dark Blue wire and the controls were in Max, Normal or Bi-Level the 12 volts should have been shorted to ground.
For C68 Auto climate control the manual says the AC request is 12 volts. (Which I believe is wrong).
For C60 Manual climate control the manual says the AC request is a ground signal (zero volts which I believe is correct).
What I notice is both AC request signals go to the PCM Black connector Pin 1.
For the C60 AC request signal at the PCM they show an Ignition voltage and a pull up resistor in the PCM block diagram. This would indicate to me when the circuit is open there is at least 12 volts at the open resistor end.
When the AC request ground signal is at Pin 1 of the PCM the open end of the resistor is now at ground level. (zero volts).
The C68 shows no pull up resistor for the AC Request signal in the PCM.
Obviously since the C60 and C68 both input to the PCM the AC Request single on the same pin 1 the signal can only be a 12 volts or Zero volts. So the description in the manual must be wrong for C68.
**************************************** **************************************** *****************
I would measure the Dark Blue wire and verify what the voltage is when you request AC and when the unit is Off.
If you placed 12 volts on the Dark Blue wire you said the scanner showed the AC Request signal, did the compressor clutch engage?
I'm looking at the 95 Helms Red two book set of Service manuals. (White colored front page are the Preliminary manuals).
The Chart 6E3-C10-5 is for a Vin J which is the ZR1.
I assumed you have a Vin P which is the LT1.
Looking at the schematic, if you jumped 12 volts to B2 the Dark Blue wire and the controls were in Max, Normal or Bi-Level the 12 volts should have been shorted to ground.
For C68 Auto climate control the manual says the AC request is 12 volts. (Which I believe is wrong).
For C60 Manual climate control the manual says the AC request is a ground signal (zero volts which I believe is correct).
What I notice is both AC request signals go to the PCM Black connector Pin 1.
For the C60 AC request signal at the PCM they show an Ignition voltage and a pull up resistor in the PCM block diagram. This would indicate to me when the circuit is open there is at least 12 volts at the open resistor end.
When the AC request ground signal is at Pin 1 of the PCM the open end of the resistor is now at ground level. (zero volts).
The C68 shows no pull up resistor for the AC Request signal in the PCM.
Obviously since the C60 and C68 both input to the PCM the AC Request single on the same pin 1 the signal can only be a 12 volts or Zero volts. So the description in the manual must be wrong for C68.
**************************************** **************************************** *****************
I would measure the Dark Blue wire and verify what the voltage is when you request AC and when the unit is Off.
If you placed 12 volts on the Dark Blue wire you said the scanner showed the AC Request signal, did the compressor clutch engage?
Ok, so my car is a LT1 and has vin P. I took a look at my book which is the same one you have and there are actually two sections for each motor one for P and one for J they both have a page 6E3-C10-5. The Chart C-10 I followed was for Vin P as it shows it at the top of the page. Also the page I scanned on my earlier post (6E3-C10-4) was right next to it and also show vin P at the top of the page. When I have the car running if I jump battery voltage to the dark blue wire on the AC head connector the AC Compressor clutch does start working! The flow chart on the VIN P 6E3-C10-5 shows doing this test in the fourth step. It really looks like I am going to be ordering a new dash unit.
Thanks for the help!
Ron
08-01-2014, 10:54 PM
#9
Melting Slicks
Member Since: Aug 1999
Location: Baltimore, MD USA
Posts: 2,240
Likes: 0
Received 34 Likes
on
30 Posts
Something fishy here. 
Here's the diagram you posted. It shows when AC is called for a ground is placed on the Dark Blue wire.
It's interesting in the troubleshooting chart they say to disconnect the plug to the HVAC control head before jumping a fused 12 volts to the Dark Blue wire.
That's why I wondered what signal voltage you would measure on the Dark Blue wire when the button was OFF and what the voltage would be when AC was called for.
Here's the diagram you posted. It shows when AC is called for a ground is placed on the Dark Blue wire.
It's interesting in the troubleshooting chart they say to disconnect the plug to the HVAC control head before jumping a fused 12 volts to the Dark Blue wire.
That's why I wondered what signal voltage you would measure on the Dark Blue wire when the button was OFF and what the voltage would be when AC was called for.
08-02-2014, 12:07 AM
#10
Intermediate
Thread Starter
Member Since: Jul 2014
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
Something fishy here.
Here's the diagram you posted. It shows when AC is called for a ground is placed on the Dark Blue wire.
It's interesting in the troubleshooting chart they say to disconnect the plug to the HVAC control head before jumping a fused 12 volts to the Dark Blue wire.
That's why I wondered what signal voltage you would measure on the Dark Blue wire when the button was OFF and what the voltage would be when AC was called for.
Here's the diagram you posted. It shows when AC is called for a ground is placed on the Dark Blue wire.
It's interesting in the troubleshooting chart they say to disconnect the plug to the HVAC control head before jumping a fused 12 volts to the Dark Blue wire.
That's why I wondered what signal voltage you would measure on the Dark Blue wire when the button was OFF and what the voltage would be when AC was called for.
So, is my manual just wacky or does yours show the same stuff?
08-02-2014, 09:41 AM
#11
Melting Slicks
Member Since: Aug 1999
Location: Baltimore, MD USA
Posts: 2,240
Likes: 0
Received 34 Likes
on
30 Posts
My manual is the same as yours. 
First picture shows the troubleshooting chart for a 93 when the clutch does not engage and is what I would expect.
The 2nd picture is the troubleshooting chart for a 95 when the clutch doesn't engage.
My conclusion is for a 93 the AC request for a C60 is a ground signal.
For a 95 the AC request for a C60 is 12 volts.
So yes you need a C60 control head for a 95.
The 95 Block diagram for a c60 is incorrect because it shows when the AC switch is on it places a ground on the Dark Blue wire when you say it places 12 volts on the Dark Blue wire. It also has an error where it says to disconnect the connector at the low pressure cycling switch and to probe terminal B when it should say probe terminal A.
First picture shows the troubleshooting chart for a 93 when the clutch does not engage and is what I would expect.
The 2nd picture is the troubleshooting chart for a 95 when the clutch doesn't engage.
My conclusion is for a 93 the AC request for a C60 is a ground signal.
For a 95 the AC request for a C60 is 12 volts.
So yes you need a C60 control head for a 95.
The 95 Block diagram for a c60 is incorrect because it shows when the AC switch is on it places a ground on the Dark Blue wire when you say it places 12 volts on the Dark Blue wire.
It also has an error where it says to disconnect the connector at the low pressure cycling switch and to probe terminal B when it should say probe terminal A. 
08-02-2014, 10:45 AM
#12
A '94 FSM mentions terminal A and NOT B also. The '96 FSM format changes somewhat so it's difficult to compare to the earlier ones.
OP - a '94 C60 AC Control is the same as you need and you could use through '96 for your needs.
OP - a '94 C60 AC Control is the same as you need and you could use through '96 for your needs.
08-02-2014, 12:23 PM
#13
Intermediate
Thread Starter
Member Since: Jul 2014
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the help everyone! I am glad that it was not just me going crazy as the FSM and google was confusing me with all the contradicting information... I agree that I think the one in my car should be placing voltage on the AC Request line and I need a new Control Head. Last night I ordered a new control head part #16170891. This should be the one that fits 94-96 and should also have the white lettering on the buttons (The one that came in the car when I bought it had orange lettering and looked to be from a 92-93). When it arrives I will let you guys know if it fixes my issue.
Thanks Again!
Ron
Thanks Again!
Ron
