Bingo002

I've posted in various threads about this issue before, but I'd like to create this one for the sake of easier tracking and to comprehensively describe the issue and what I've done. It should be noted that my car has more or less had this issue since I bought it 8 months ago.

Issue: My HVAC is all sorts of screwed up. It should be noted that the display on the panel behaves correctly and responds to my inputs.

• The blower can be turned up incrementally but not down without turning off the entire system or a key cycle.
• The directional airflow button does nothing. Air only comes out of the front 4 vents with a small amount coming out at the windshield.
• Temperature dial is almost binary, 60-70 is cold AC, 70-90 is hot air.

I found that my compressor was hit by something that took out the clutch a couple weeks back. I replaced the compressor and evac/recharged the system so that cold air was felt.
Since that replacement, the passenger side vents behave as described above, but the driver side vents only blow heat no matter what temperature is selected. I can reset the battery, and the driver side will work for a day or two, then go back to heat. Again, the passenger side does not have this issue.

What I've done:

• Replaced the blend door actuator
• Taken out the HVAC unit, checked for continuity (each button did yield a connection to various pins, but I do not have a schematic outlining which pins should come alive so I'm just guessing here).
• Re-soldered every solder joint on the panel that I could access.
• Replaced the compressor and charged the system.
• Checked the pins on the BCM and did not see any bent or broken pins.

Now, I'm very much a DIY kind of person, but this has gone on long enough and I'm about ready to take my financial status and pride out back with a baseball bat and beat it via taking the car to a dealer for diagnosis and repair.
This post is a last resort before I do that. The only other things I can think of doing are just replacing the HVAC control unit (waiting for a partout to snag one) or the BCM. Both would be guessing with $100's which I despise doing. I feel like I'm lost at this point, and any help or guidance is appreciated.

Gator6977

My wife's Acadia did the same thing as your experiencing with the heat coming out of one side. It was the blend door actuator, but that thing has four of them. Corvette shows two, might not hurt to change the other one. 22754988 and 22754989. With regards to your fan speed and temp control issues, my knee jerk reaction of the control head. Hopefully someone can chime in with more insight. Good luck man, sucks you're having these issues.

Coach Vail

I am having issues with mine as well. I get no heat and no A/C, but the fan blows and the vents all seem to properly disperse the outside air that blows. All I'm getting is air at the outside temperature. Had the water pump replaced a few weeks ago, and the service tech mentioned that the A/C needed recharged, which he did. Haven't had air or heat since.
Suggestions?

taguid

Do you have a tech II to check for codes? That would be a great place to start to get a good diagnosis of the problem.

Coach Vail

I don't but looks like I should get one. Suggestions on what to buy?

Gator6977

If bet he overcharged the system. If the system detects too much, or too little, pressure it will not blow cold. Usually the the AC button will blink three times when this is the case. It also means there are codes stored, if you have a tech 2 to read them.

K-Spaz

Doesn't sound at all to me like you have a electronic problem. Maybe the C6 is just getting old enough that it is now having the same age issues as the C5. I would be looking at the vacuum system that supplies motion to the doors rather than worrying about blend door issues. Blend the doors are electronic, Direction doors are vacuum. They are a All or Nothing condition.

With that said, I'm not familiar with the C6 AC because I haven't had to fix mine. But I am intimately familiar with the C5 and that's where I'd be checking. If they routed things similarly, you might be taking the inner Fender off the passenger side and fixing things in there or running new emissions tubing to supply vacuum in the cabin.

Coach Vail

I bought a code reader and got B0268 and B0269 codes. Appears to be electronic?

johan gouws

I had hot air only on the passenger side some time ago. Blender door issues were suggested by some. To big a job for me so I took it to the dealer and had it fixed. Dealer reported it was the head unit that went faulty and said that the blender doors were fine.Still going strong - touch wood.

Bingo002

2 year thread bump by the OP, wonder if there's anything new out there. I replaced the HVAC control unit and the symptoms are the same (see original post). It doesn't bother me enough to get bent over by a shop or dealership, so does anyone have any ideas?

torquetube

Check the system for HVAC codes. This requires a Corvette-aware code reader like a Tech 2. They won't turn on a check engine light. You have to go looking for them.

Look for a shredded mode door ("mode valve" in GM-ese). You can probably partially see it with a flashlight looking down the center console vents and the vent on the top of the dash. As you cycle through the different vent combinations, the piano roll gizmo should scroll up and down, hiding/revealing holes for air distribution. If you hear the motor but nothing's happening, the scroll is probably broken.

J3TVETTE

When one of my C6's blew warm air from the passenger side but cold air on the drivers side it turned out to be a pressure issue. I took it to an AC repair shop and had them recharge the system and it started blowing cold on both sides. I had initially assumed it was a blend door as well.

Bingo002

I've seen multiple people talk about different temps air on driver vs passenger sides, this is not an issue on my car. My issue is only the blower ramp down and directional air. BCM is my best guess, but I really don't wanna go that route...

J3TVETTE

The BCM is my guess as well based on what I read in your post as well. Since you already replaced the HVAC unit there is not much else to change. BCM at a dealer will probably run over $1000 unfortunately. You can probably grab one on ebay from a used car and find someone with a tech ii to program it.