Zr1 - different C68 programmer

[S.hafsmo]

My climate control panel shows only 3 dashes (---) and does not respond to input, other than for fault code reading. Though no codes show. Fan blows constantly to windshield when ignition is on.

Having attempted some fixes (headunit eraser/cleaning and programmer capacitor replacement) without the desired success, I've started glancing for a replacement while the fault finding continues. I notice the Z programmet have a different part number, which naturally makes it 3-4 times as expensive. Why? Can I not use a programmer for a regular C4? Any hints on where to acquire one that does not cost $700?

[Roadster]

My climate control panel shows only 3 dashes (---) and does not respond to input, other than for fault code reading. Though no codes show. Fan blows constantly to windshield when ignition is on.

Having attempted some fixes (headunit eraser/cleaning and programmer capacitor replacement) without the desired success, I've started glancing for a replacement while the fault finding continues. I notice the Z programmet have a different part number, which naturally makes it 3-4 times as expensive. Why? Can I not use a programmer for a regular C4? Any hints on where to acquire one that does not cost $700?

I think I understand what you are saying, and if so, what you need to do is take out the Climate Control Panel and clean all of the contacts. The thread below I posted a year and a half ago on this procedure. I found the info on You Tube, and it works great. If you do this you may not have to purchase another unit....

http://www.zr1.net/forum/showthread.php?t=25372

[S.hafsmo]

That was the first thing I tried, but I appreciate the input. The buttons respond fine when I activate the trouble code programme (hold up+down for 5 sec), but the head unit does not show temperature, nor indicate mode with the diodes.

Looks like this (borrowed pic)
https://uploads.tapatalk-cdn.com/20170214/3c35bf250cdddfe7718122aeb0bb8156.jpg

It's the exact same issue as this guy had.
http://www.digitalcorvettes.com/forums/showthread.php?t=118406

[G8nightman]

Maybe some moister or water got on to it?

[Roadster]

You would probably have to check out the FSM for that one....Don't know if you own the Service Manuals for your year, but that would be a very good investment. I will take a look at my FSM and see if I can find anything for you. And there may be another member who have experienced this problem and respond....

[S.hafsmo]

The circuit board in both the programmer and headunit looks mint, even the cardboard on the back looks good. I've checked the FSM, but offcourse I was missing the 8A electronics supplement. Was really hoping to see an obvious defect when I opened it, but no such luck

[Roadster]

This is what I found, and you may also found the same....

From the FSM....
"The computerized HVAC programmer receives input from several on-vehicle sensors, the CCM, also temperature and mode requests from the HVAC control head."
"The information input to the HVAC programmer is processed and used to control the electronic automatic HVAC system.
Three sensors, specific to the electronic automatic HVAC system provide input to the HVAC programmer."

1-OUTSIDE AIR (AMBIENT) TEMPERATURE SENSOR
2-INSIDE AIR TEMPERATURE SENSOR
3-SUN LOAD SENSOR

I could not find any info on a non-functioning LCD display with or without the 3 dashes (---).
Could it be that one of the sensors or the CCM is defective, therefore causing you not to get the reading on the LCD and thus the system not operating properly???
Thinking logically, the sensors mentioned and or the CCM may need to be checked out for proper operation...

[WVZR-1]

See 1C1-22 for a '90 (CODE 10 or ---) If year other than '90 the ERROR CODE should be found on a similar/close to page. The failure isn't likely internal to the C68 control.

***If you don't have an FSM or maybe just not the 8A which is relevant here drop me an email. I can do a .pdf complete that is way better than most, both books, the '90 - '93 LT5 supplement a couple parts SPO publications that I had done for me professionally.

We can do the FSM via "DropBox" and you can have same day paid PayPal. I've done many. My .pdf is searchable and you can clip images and sections of text from it that most .pdf can't.

[GOLDCYLON]

My climate control panel shows only 3 dashes (---) and does not respond to input, other than for fault code reading. Though no codes show. Fan blows constantly to windshield when ignition is on.

Having attempted some fixes (headunit eraser/cleaning and programmer capacitor replacement) without the desired success, I've started glancing for a replacement while the fault finding continues. I notice the Z programmet have a different part number, which naturally makes it 3-4 times as expensive. Why? Can I not use a programmer for a regular C4? Any hints on where to acquire one that does not cost $700?

These are not ZR-1 specific however they are C4 specific. You will need to find a model that works for your year car. I think 90-91 are a break point then 92-93 and 94-96. So that's 3 different models. Regardless there are no ZR-1 Specific C-68 AC programmers. The model years are the difference. What changed I have no idea between the model(s) but the 134A to R12 break was in the 94 model this is a WAG although but I know there are multiple part numbers for these controllers out there.

[RodB]

I had this problem on my MY90 several years ago so this info isn't fresh in my mind but I called Gordon Kilebrew and we were able to resolve it. One of his tricks was to remove the blower motor resistor from the heater box. That allows you to look at a flapper that directs air to different positions. As I recall his advise was to remove and replace the battery cable and that causes the flapper to cycle and reset. His concern was that at least on MY90s was that the only thing to stop the flapper was the small tab that stops rotation had probably broken. Apparently repairing a faulty flapper is a royal PITA. Luckily for me it rotated and stopped as it should. From there we determined that the HVAC controller was the problem. I found one on eBay and I don't remember that it was a zr1 specific part. It is beside the steering column behind the hush panel and in its own right it is a PITA to replace. That did work for me and all these years later I've had no more issues. Gordon said that if the head unit doesn't see the return signals that it expects it just locks.

Like I say this if I went through this five days ago instead of five years my memory might be better but I do remember Gordon originally was concerned that the flapper just going around and around. Hope this helps.


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[S.hafsmo]

Appreciate the input, gentlemen.
All topics I've found on the subject, end with the programmer being replaced. Except this one, where he replaces the caps. This however, did not solve it in my case.
http://www.corvetteforum.com/forums/c4-tech-performance/3410477-94-hvac-a-c-failure-programmer-repaired.html

Wouldn't a faulty sensor give the appropriate fault code?

I'll keep my eyes open for a 90-91 programmer.

Edit,
Rod, did you also have those dashes? I'll have to check the flap as well, just in case.

[RodB]

The display did read - - - but I don't recall the fan running at full tilt but it could have been. I thought having the FSM would help me solve the problem but I couldn't find this exact problem addressed. I guess Gordon kept a few ideas for himself!


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[S.hafsmo]

Found this statement in the 8A supplement.
"Three dashes will be displayed on the Heater and A/C Control Head if the A/C Programmer fails." Not all to useful, but at least it also points to the programmer.

Edit: additional FSM info,
https://uploads.tapatalk-cdn.com/20170214/7fb49815fed6951c4a46d623e717bb40.jpg

[S.hafsmo]

An other old thread with the same issue. I'm just collecting info here in this thread so I can find it when I get back home.

http://www.corvetteforum.com/forums/c4-tech-performance/997104-c68-air-conditioning-problem-pics-inside.html

[mike100]

... I think 90-91 are a break point then 92-93 and 94-96. So that's 3 different models. ...

I can confirm that my old 95 coupe had a different program as more selections ran with a/c rather than just vent air as my 91 does.

[Marc Haibeck]

For parts interchange I can add what has worked for me. A '91 or '92 or '93 ZR-1 Programmer will work if it is used with a '91 or '92 or '93 button panel. If an 08 sun sensor errors occurs, cover the sensor with tape.

[S.hafsmo]

If the 90 and 91s apparently are compatible, would that entail that a programmer from the model years you mention also could work on a '90?

I've gone through the FSM fault finding, and it just ends on "replace programmer". I've resoldered everything, measured all diodes, replaced all capacitors, and checked the board while live (connected/ign. On) with freezing spray to check for hotspots. Nothing. Getting close to giving up on this one.

[Marc Haibeck]

Yes, '91 to '93 Programmers should work on a '90. It may be necessary to use the matching model year button panel.

I tried fixing a '94 Programmer with capacitors and freeze spray, just like you. Sometimes it worked when the large IC chip was frozen. But it never worked at room temperature. BTW, the earlier Programmers will not work on a '94. I had to find a '94 Programmer to fix the '94.