Hello,

I recently purchased a 95 Corvette with under 50k miles. It has the C68 digital climate control, and so far I have had nothing but problems with it. I did a search on here and on google as well and I have found only limited information on this issue; I am hoping someone has a clue how to diagnose this. The problem started with the outside temperature fluctuating like crazy and reading way too high or low and a code 02 & 03. Then I had issues with the fan speed. Yesterday I realized that I only have air conditioning and no heat.

Here is how I attempted to resolved the problem so far: I replaced the outside temp sensor and that cured the reading issues. The code for 02 & 03 went away, but now I have a code for 01. I removed the dash and found that the blend door actuator is not damaged but its is acting very strangely. If I push the blend door all the way open for heat it will close when I turn on the A/C. When commanding heat once more it will not move over. What it will do is rock back and forth. I also noticed that the blend door is always moving, and the actuator is going back and forth, very little but its moving and you can hear it moving. I found a you tube video in regard to cleaning the C68 controls and since the dash was apart anyway I figured I would disassemble it and clean it. It made no difference. If anyway has an idea on where I should be focusing my efforts I would appreciate it. Also a flow chart from the FSM would be very helpful as well!

Thanks,
Dan

 

01 and 02 are both blend motor circuit faults. So 02 going away with the outside air temp sensor may be coincidence. The 01 seems consistent with the blend doors behavior.

Normally yhe first step with a C68 ssytem is to disconnec the battey for 1 minute and the system resets itself. If problems persist then follow teh trouble shooting procedures from the FSM.

This link is from batee.com. He's pretty much the guy for repair of the HVAC components.

90-96 HVAC section of FSM

My gut says bad position sensor in the blend door motor assy.

 

I reset the battery. The same problem persisted. Thank you for the flow chart. Now I have a direction to move in!

DG

 

When you turn the key on, listen for a clicking sound coming from the passenger footwell. If you hear that, it likely means that there is a problem with the plastic gear inside the blend door actuator. It's not too hard to replace the actuator on the later C4s, but the replacement may have a slightly different case than the original. This may require that the actuator case or the blend door housing be trimmed slightly to fit.

 

Had a similar issue on my 96 . i posted about it. See link down below . Also had codes 01 and 02 .. , but the AC would blow cold for 30 sec , then go warm for 15 sec . this would just keep repeating itself. While operating ,i could look down there and see the blend door moving in unison with temp changes in car. replaced blend door actuator ,,problem solved. Took cover off removed unit and the plastic gear was cracked all the way from shaft to teeth allowing it to slip.

See this post . It also explains how to get the doorman unit to fit properly.
https://www.corvetteforum.com/forums...r-acuator.html

 

Fixed using flow chart. You guys were correct, turned out to be the Blend door actuator after all, specifically the potentiometer. I opened the old one and the gears looked great but it was unable to figure out what direction it was going in. I shimmed the mounting tabs and it slid right into place. Its nice to have heat now that its getting cooler here.

Thanks!

Dan

 

1996 LT4.
Hello, I replaced my blend motor and I am still getting the 01 code. Temperature is still fluctuating. The clicking sound is gone which made me think it was working properly so I put everything back together. Temperature still fluctuating. Any help would be appreciated on next steps. Thank you.