C68 Electronic Climate Control Code 02
Thread Starter
Heel & Toe
Joined: May 2002
Posts: 21
Likes: 0
From: San Diego CA
C68 Electronic Climate Control Code 02
I have a 1990 L98 C4 Corvette with a C68 Electronic Climate Control. The system had not been working correctly so I reseated the frame grounds, installed a rebuilt programmer and head unit, and a new air mix door actuator. Currently, when the vette is started the LED above a mode button (doesn't make any difference which button selected) flashes for about 30 seconds after which the climate control system functions normally while the vette is being driven. The error code in the error display is an 02. The results from a second rebuilt programmer are the same. From the FSM I have run the diagnostics for the code 02 error. Step 1 is to disconnect the battery with the ignition off and reinstall after 15 seconds. The code does not reset. The FSM states that if the code 02 did not reset, the system is OK.
So the system is OK, but operation always results in a code 02. Anybody have any idea what is going on or what to do about it?
So the system is OK, but operation always results in a code 02. Anybody have any idea what is going on or what to do about it?
Thread Starter
Heel & Toe
Joined: May 2002
Posts: 21
Likes: 0
From: San Diego CA
From FSM the Code 02 is Temp. Door Motor Circuit Fault. The system was having a variety of other problems before the repairs and had no ability to display error code or parameter information. The Air Mix Door Actuator contains both the temperature door motor and a position feedback potentiometer (variable resistor). Parameter 34, Temperature Door Feedback, is at -153 (253) at full cold and 00 at full hot (range is 255 full hot and 00 full code). Maybe the door is not getting a full travel?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
From FSM the Code 02 is Temp. Door Motor Circuit Fault. The system was having a variety of other problems before the repairs and had no ability to display error code or parameter information. The Air Mix Door Actuator contains both the temperature door motor and a position feedback potentiometer (variable resistor). Parameter 34, Temperature Door Feedback, is at -153 (253) at full cold and 00 at full hot (range is 255 full hot and 00 full code). Maybe the door is not getting a full travel?
I will try to explain what's happening in simple terms. Codes 1 and 2 are set when the programmer does not like the feedback voltage in regard to the blend door position. This is usually caused by the blend door motor (and not the programmer).
There is a calibration between the full swing of each position of the door and the feedback voltage from the potentiometer inside the motor assembly. Sometimes age or water intrusion can cause a problem. If the evaporator drain is clogged, water can back up into motor and cause problems.
I don’t think the doors jam and restrict movement.
Many people have replaced the blend door motor and solved these kind of problems. I think this is a good place to start.
Information on this is in the FSM, but actual repairs are not a walk in the park.
Thread Starter
Heel & Toe
Joined: May 2002
Posts: 21
Likes: 0
From: San Diego CA
Bill, you have confused the error codes with the parameters that you can scan thru. A simple mistake.
This is all basically correct.
I will try to explain what's happening in simple terms. Codes 1 and 2 are set when the programmer does not like the feedback voltage in regard to the blend door position. This is usually caused by the blend door motor (and not the programmer).
There is a calibration between the full swing of each position of the door and the feedback voltage from the potentiometer inside the motor assembly. Sometimes age or water intrusion can cause a problem. If the evaporator drain is clogged, water can back up into motor and cause problems.
I don’t think the doors jam and restrict movement.
Many people have replaced the blend door motor and solved these kind of problems. I think this is a good place to start.
Information on this is in the FSM, but actual repairs are not a walk in the park.
This is all basically correct.
I will try to explain what's happening in simple terms. Codes 1 and 2 are set when the programmer does not like the feedback voltage in regard to the blend door position. This is usually caused by the blend door motor (and not the programmer).
There is a calibration between the full swing of each position of the door and the feedback voltage from the potentiometer inside the motor assembly. Sometimes age or water intrusion can cause a problem. If the evaporator drain is clogged, water can back up into motor and cause problems.
I don’t think the doors jam and restrict movement.
Many people have replaced the blend door motor and solved these kind of problems. I think this is a good place to start.
Information on this is in the FSM, but actual repairs are not a walk in the park.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Just to go out on a limb, sometimes low Freon will cause the LED to flash. It may need a bit of Freon, just a suggestion.
Looking at the door thru the evaporator is good. But if you removed the motor you can then move the shaft with your fingers and feel any resistance. It should be real free. PIA
I would also try to reset the programmer just to see if it made any difference.
If you want to get technical, you can back probe the feedback voltage and monitor what it is to see what really going on. I spent a long time working on mine and got really deep into it. The FSM tells you the resistance range of the potentiometer but does not give you a voltage range. I measured mine and your numbers I would think should be close to yours. From cold to hot (60-90) I measured 0.9 - 4.4 volts.These numbers are dependent on whether the engine is running due to battery voltage or full voltage. But I think I did it with the engine off ??
If it makes you feel any better, my LED flashes from time to time. I check for codes, no hard failure and all works OK.
Looking at the door thru the evaporator is good. But if you removed the motor you can then move the shaft with your fingers and feel any resistance. It should be real free. PIA
I would also try to reset the programmer just to see if it made any difference.
If you want to get technical, you can back probe the feedback voltage and monitor what it is to see what really going on. I spent a long time working on mine and got really deep into it. The FSM tells you the resistance range of the potentiometer but does not give you a voltage range. I measured mine and your numbers I would think should be close to yours. From cold to hot (60-90) I measured 0.9 - 4.4 volts.These numbers are dependent on whether the engine is running due to battery voltage or full voltage. But I think I did it with the engine off ??
If it makes you feel any better, my LED flashes from time to time. I check for codes, no hard failure and all works OK.
Thread Starter
Heel & Toe
Joined: May 2002
Posts: 21
Likes: 0
From: San Diego CA
Just to go out on a limb, sometimes low Freon will cause the LED to flash. It may need a bit of Freon, just a suggestion.
Looking at the door thru the evaporator is good. But if you removed the motor you can then move the shaft with your fingers and feel any resistance. It should be real free. PIA
I would also try to reset the programmer just to see if it made any difference.
If you want to get technical, you can back probe the feedback voltage and monitor what it is to see what really going on. I spent a long time working on mine and got really deep into it. The FSM tells you the resistance range of the potentiometer but does not give you a voltage range. I measured mine and your numbers I would think should be close to yours. From cold to hot (60-90) I measured 0.9 - 4.4 volts.These numbers are dependent on whether the engine is running due to battery voltage or full voltage. But I think I did it with the engine off ??
If it makes you feel any better, my LED flashes from time to time. I check for codes, no hard failure and all works OK.
Looking at the door thru the evaporator is good. But if you removed the motor you can then move the shaft with your fingers and feel any resistance. It should be real free. PIA
I would also try to reset the programmer just to see if it made any difference.
If you want to get technical, you can back probe the feedback voltage and monitor what it is to see what really going on. I spent a long time working on mine and got really deep into it. The FSM tells you the resistance range of the potentiometer but does not give you a voltage range. I measured mine and your numbers I would think should be close to yours. From cold to hot (60-90) I measured 0.9 - 4.4 volts.These numbers are dependent on whether the engine is running due to battery voltage or full voltage. But I think I did it with the engine off ??
If it makes you feel any better, my LED flashes from time to time. I check for codes, no hard failure and all works OK.
Melting Slicks
Joined: Oct 2016
Posts: 2,024
Likes: 363
From: Central Alabama
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Thread Starter
Heel & Toe
Joined: May 2002
Posts: 21
Likes: 0
From: San Diego CA
The 1990 has the blend door actuator on the top of the heater core case and requires disassembly of the passenger side dash and engine compartment blower case. I have read that some owners with older C4s have switched to the heater core cases with the blend door actuator on the bottom. I am considering doing this switch.
