Automatic Climate Control - Unresponsive - '94 Convertible
10-12-2013, 05:16 PM
#1
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Automatic Climate Control - Unresponsive - '94 Convertible
I know there are a ton of posts on climate control but I haven't yet found one that exactly matches my symptoms.
The panel is backlit but doesn't display anything. I installed a new (rebuilt) panel from Eckler's today (yes I know I am 'throwing parts' at it but it seemed logical).
The new panel does exactly the same thing.
I noticed there is a disconnected plug near the blower fan motor (yellow and grey wire), I found that on the wiring diagram, it looks like it goes between the "ACC Selector Switch" and the "Outside Air/Re-circulation Door Actuator". But I cannot for the life of me find the plug to connect it to. Not sure if that would fix the problem but probably something that needs to be addressed.
So Plan A is to actually fix this...Plan B is to turn the heat on so that at least I can drive it without freezing to death. It's current status is it flows cold air with AC on through the defrost vents. My thought was if I could manually set the temperature control to warm it would last me me until it can be fixed.
From other posts i thought I could access the temperature control door behind the blower fan, I have the blower fan off but the door is not obvious (at least not to me).
Thoughts/Insight?
Thanks!
The panel is backlit but doesn't display anything. I installed a new (rebuilt) panel from Eckler's today (yes I know I am 'throwing parts' at it but it seemed logical).
The new panel does exactly the same thing.
I noticed there is a disconnected plug near the blower fan motor (yellow and grey wire), I found that on the wiring diagram, it looks like it goes between the "ACC Selector Switch" and the "Outside Air/Re-circulation Door Actuator". But I cannot for the life of me find the plug to connect it to. Not sure if that would fix the problem but probably something that needs to be addressed.
So Plan A is to actually fix this...Plan B is to turn the heat on so that at least I can drive it without freezing to death. It's current status is it flows cold air with AC on through the defrost vents. My thought was if I could manually set the temperature control to warm it would last me me until it can be fixed.
From other posts i thought I could access the temperature control door behind the blower fan, I have the blower fan off but the door is not obvious (at least not to me).
Thoughts/Insight?
Thanks!
10-13-2013, 03:50 AM
#3
Race Director
We need to know a few things first...
What year is the car? That makes a major difference.
Do you have the C60 manual HVAC system or the C68 automatic HVAC system? That also makes a major difference. I assume it's the C68 system since you say it doesn't display anything, which implies that it does have a display.
The temperature door (most people call it a "blend door") is located inside the evaporator housing. You remove the resistor module if you have a C60 system or the blower control module if you have a C68 system and you can see the blend door through the opening. It looks like this (the rusty thing -- 60°F position in the first pic, 90°F position in the second pic -- those are the C68 positions. Minimum temperature and maximum temperature for C60 systems):
It's possible that your car is different (year?), but on my car the outside air door is vacuum controlled. It's inside the car by the passenger's right foot, so that plug is unlikely to go there.
You could disable the AC compressor. On earlier years it is controlled by the blower module. Later years have a relay. Unplugging the compressor ought to do it.
Check your A/C fuse.
What year is the car? That makes a major difference.
Do you have the C60 manual HVAC system or the C68 automatic HVAC system? That also makes a major difference. I assume it's the C68 system since you say it doesn't display anything, which implies that it does have a display.
The temperature door (most people call it a "blend door") is located inside the evaporator housing. You remove the resistor module if you have a C60 system or the blower control module if you have a C68 system and you can see the blend door through the opening. It looks like this (the rusty thing -- 60°F position in the first pic, 90°F position in the second pic -- those are the C68 positions. Minimum temperature and maximum temperature for C60 systems):
It's possible that your car is different (year?), but on my car the outside air door is vacuum controlled. It's inside the car by the passenger's right foot, so that plug is unlikely to go there.
You could disable the AC compressor. On earlier years it is controlled by the blower module. Later years have a relay. Unplugging the compressor ought to do it.
Check your A/C fuse.
Last edited by Cliff Harris; 10-13-2013 at 03:53 AM.
10-13-2013, 06:58 AM
#4
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We need to know a few things first...
What year is the car? That makes a major difference.
Do you have the C60 manual HVAC system or the C68 automatic HVAC system? That also makes a major difference. I assume it's the C68 system since you say it doesn't display anything, which implies that it does have a display.
The temperature door (most people call it a "blend door") is located inside the evaporator housing. You remove the resistor module if you have a C60 system or the blower control module if you have a C68 system and you can see the blend door through the opening. It looks like this (the rusty thing -- 60°F position in the first pic, 90°F position in the second pic -- those are the C68 positions. Minimum temperature and maximum temperature for C60 systems):
It's possible that your car is different (year?), but on my car the outside air door is vacuum controlled. It's inside the car by the passenger's right foot, so that plug is unlikely to go there.
You could disable the AC compressor. On earlier years it is controlled by the blower module. Later years have a relay. Unplugging the compressor ought to do it.
Check your A/C fuse.
What year is the car? That makes a major difference.
Do you have the C60 manual HVAC system or the C68 automatic HVAC system? That also makes a major difference. I assume it's the C68 system since you say it doesn't display anything, which implies that it does have a display.
The temperature door (most people call it a "blend door") is located inside the evaporator housing. You remove the resistor module if you have a C60 system or the blower control module if you have a C68 system and you can see the blend door through the opening. It looks like this (the rusty thing -- 60°F position in the first pic, 90°F position in the second pic -- those are the C68 positions. Minimum temperature and maximum temperature for C60 systems):
It's possible that your car is different (year?), but on my car the outside air door is vacuum controlled. It's inside the car by the passenger's right foot, so that plug is unlikely to go there.
You could disable the AC compressor. On earlier years it is controlled by the blower module. Later years have a relay. Unplugging the compressor ought to do it.
Check your A/C fuse.
Any insight on the orphan plug?
10-13-2013, 08:13 AM
#5
Earlier year shown but the motor that moves the door ( that can only be seen from underneath
the dash ) is in a similar location
IIRC your year has the motor driving the door directly without the linkage shown
10-15-2013, 05:09 PM
#8
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Ok so I went through entire fuse box and tested every fuse, my interior lights work now (woohoo) but it didn't help the climate control.
I have a service manual and the troubleshooting in it will be very helpful but it seems to start from the control working but 'no cold', 'no heat', etc...
If I'm missing the 'nothing works at all section' please point me in the right direction.
Any help, ideas, or encouragement would be appreciated
I have a service manual and the troubleshooting in it will be very helpful but it seems to start from the control working but 'no cold', 'no heat', etc...
If I'm missing the 'nothing works at all section' please point me in the right direction.
Any help, ideas, or encouragement would be appreciated
10-15-2013, 05:42 PM
#10
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What year is yours? I didn't see a big fuse (I assume you mean under the hood) labeled AC, I'll look again
10-15-2013, 05:54 PM
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10-16-2013, 02:31 AM
#13
Race Director
You still need to pull out the blower control module and look at the blend door.
When the ignition is first turned on the HVAC control head moves the blend door fully cold and fully hot to calibrate the extremes. Then it sets the blend door to the position indicated by the temperature setting on the control head. It takes about 15 seconds to do the calibration. You can watch it happen through the blower control module opening. If I have the radio turned off and the blower control module disconnected I can hear the blend door motor doing the calibration.
It's possible that your HVAC programmer has a problem. It drives the blend door motor. It's located above the accelerator pedal. It's common for the resistors to burn up. If one burns open the blend door will get stuck at one extreme. Here's a link with way more information than you need ;-):
http://forums.corvetteforum.com/c4-t...schematic.html
If you scroll down a bit in that thread there is a picture of the HVAC programmer PC board that shows the resistors that get hot.
When the ignition is first turned on the HVAC control head moves the blend door fully cold and fully hot to calibrate the extremes. Then it sets the blend door to the position indicated by the temperature setting on the control head. It takes about 15 seconds to do the calibration. You can watch it happen through the blower control module opening. If I have the radio turned off and the blower control module disconnected I can hear the blend door motor doing the calibration.
It's possible that your HVAC programmer has a problem. It drives the blend door motor. It's located above the accelerator pedal. It's common for the resistors to burn up. If one burns open the blend door will get stuck at one extreme. Here's a link with way more information than you need ;-):
http://forums.corvetteforum.com/c4-t...schematic.html
If you scroll down a bit in that thread there is a picture of the HVAC programmer PC board that shows the resistors that get hot.
10-16-2013, 08:21 PM
#14
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You still need to pull out the blower control module and look at the blend door.
When the ignition is first turned on the HVAC control head moves the blend door fully cold and fully hot to calibrate the extremes. Then it sets the blend door to the position indicated by the temperature setting on the control head. It takes about 15 seconds to do the calibration. You can watch it happen through the blower control module opening. If I have the radio turned off and the blower control module disconnected I can hear the blend door motor doing the calibration.
It's possible that your HVAC programmer has a problem. It drives the blend door motor. It's located above the accelerator pedal. It's common for the resistors to burn up. If one burns open the blend door will get stuck at one extreme. Here's a link with way more information than you need ;-):
http://forums.corvetteforum.com/c4-t...schematic.html
If you scroll down a bit in that thread there is a picture of the HVAC programmer PC board that shows the resistors that get hot.
When the ignition is first turned on the HVAC control head moves the blend door fully cold and fully hot to calibrate the extremes. Then it sets the blend door to the position indicated by the temperature setting on the control head. It takes about 15 seconds to do the calibration. You can watch it happen through the blower control module opening. If I have the radio turned off and the blower control module disconnected I can hear the blend door motor doing the calibration.
It's possible that your HVAC programmer has a problem. It drives the blend door motor. It's located above the accelerator pedal. It's common for the resistors to burn up. If one burns open the blend door will get stuck at one extreme. Here's a link with way more information than you need ;-):
http://forums.corvetteforum.com/c4-t...schematic.html
If you scroll down a bit in that thread there is a picture of the HVAC programmer PC board that shows the resistors that get hot.
10-17-2013, 02:45 AM
#15
Race Director
The only thing I can think of that is in that area is the feedback fuse. It is in the wiring that tells the HVAC control head what speed the blower motor is turning.
Coolant overflow tank level? My car doesn't have one, so I can't look into that.
Coolant overflow tank level? My car doesn't have one, so I can't look into that.
10-17-2013, 07:10 AM
#16
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What year is yours? I definitely do not have a fuse there, what is the small box to the left of the fuse in the pic?
10-18-2013, 02:57 AM
#17
Race Director
02-15-2016, 08:23 PM
#18
I know there are a ton of posts on climate control but I haven't yet found one that exactly matches my symptoms.
The panel is backlit but doesn't display anything. I installed a new (rebuilt) panel from Eckler's today (yes I know I am 'throwing parts' at it but it seemed logical).
The new panel does exactly the same thing.
I noticed there is a disconnected plug near the blower fan motor (yellow and grey wire), I found that on the wiring diagram, it looks like it goes between the "ACC Selector Switch" and the "Outside Air/Re-circulation Door Actuator". But I cannot for the life of me find the plug to connect it to. Not sure if that would fix the problem but probably something that needs to be addressed.
So Plan A is to actually fix this...Plan B is to turn the heat on so that at least I can drive it without freezing to death. It's current status is it flows cold air with AC on through the defrost vents. My thought was if I could manually set the temperature control to warm it would last me me until it can be fixed.
From other posts i thought I could access the temperature control door behind the blower fan, I have the blower fan off but the door is not obvious (at least not to me).
Thoughts/Insight?
Thanks!
The panel is backlit but doesn't display anything. I installed a new (rebuilt) panel from Eckler's today (yes I know I am 'throwing parts' at it but it seemed logical).
The new panel does exactly the same thing.
I noticed there is a disconnected plug near the blower fan motor (yellow and grey wire), I found that on the wiring diagram, it looks like it goes between the "ACC Selector Switch" and the "Outside Air/Re-circulation Door Actuator". But I cannot for the life of me find the plug to connect it to. Not sure if that would fix the problem but probably something that needs to be addressed.
So Plan A is to actually fix this...Plan B is to turn the heat on so that at least I can drive it without freezing to death. It's current status is it flows cold air with AC on through the defrost vents. My thought was if I could manually set the temperature control to warm it would last me me until it can be fixed.
From other posts i thought I could access the temperature control door behind the blower fan, I have the blower fan off but the door is not obvious (at least not to me).
Thoughts/Insight?
Thanks!
I know your thread is several years old now, but did you ever find out what was causing your problem? I have a 94 with the same problem...back light works in the climate control, but no display and the buttons don't work. Thanks
02-15-2016, 09:51 PM
#19
Is the outside temp sensor hooked up?