AC blows out floor and defrost vents?

[CamP]

My 1990 ZR-1 with C68 AC is not blowing air out of the dash air vents. It is blowing cold air out of the floor and defrost vents. Anyone else have this issue?

[GOLDCYLON]

Originally Posted by CamP

My 1990 ZR-1 with C68 AC is not blowing air out of the dash air vents. It is blowing cold air out of the floor and defrost vents. Anyone else have this issue?

The problem is your HVAC controller located above the gas pedal and it is a bear to get to. You will need to source a replacement. At least it's not a ZR-1 only part. I remember somebody on the board here who was able to rebuild his but that was a long while ago.

[DRM500RUBYZR-1]

That is the default mode when failed, so that you can see in the cold or wet when defrost or defog is required.

Go to BATEE.com
Bryan's site can help you determine and confirm which part has failed.
As the poster above said, likely the controller, but there are multiple components that could cause this.

Not complex if the programmer or controller.
Check out his site.
He is THE BEST!

www.batee.com


Marty

[CamP]

Originally Posted by DRM500RUBYZR-1

That is the default mode when failed, so that you can see in the cold or wet when defrost or defog is required.

Go to BATEE.com
Bryan's site can help you determine and confirm which part has failed.
As the poster above said, likely the controller, but there are multiple components that could cause this.

Not complex if the programmer or controller.
Check out his site.
He is THE BEST!

www.batee.com


Marty

I spoke to Bryan. He thinks I have a vacuum issue because all my electronic control buttons work. Probably a simple problem that will be difficult to find.

[secondchance]

Below Is QB93Z thread on replacing the programmer.
http://www.zr1.net/forum/showthread.php?t=27542

Jim as far as I know went in the deepest with HVAC diagnose and repair.
Reach out to Jim (QB93Z) and tap his knowledge.

Good luck!

[CamP]

Originally Posted by secondchance

Below Is QB93Z thread on replacing the programmer.
http://www.zr1.net/forum/showthread.php?t=27542

Jim as far as I know went in the deepest with HVAC diagnose and repair.
Reach out to Jim (QB93Z) and tap his knowledge.

Good luck!

Thanks for that link. It appears that a kinked vacuum line under the passenger side hush panel fixed his similar issue.

I hope it's that easy! I replaced the ac programmer back in '97 and that job was no fun!

[secondchance]

Think positive, Cam!
I replaced a heater core for one of the Wazoo guys a few years ago and it was 10 hours of fun. Only had 3 7mm hexes and a 2? long plastic tube I couldn?t account for despite careful bagging and tagging.

[DRM500RUBYZR-1]

Insufficient vacuum is often found to be the culprit for the inability to direct air out of the selected vents.
The programmer is often suspect, however there is about a 1 in 3 chance that the supply vacuum is the actual cause. Squashed, kinked, cut, or varmint chewed hose in that order have all been found.
If the supply is good, then the hose connections on the programmer are the next stop.
These components are all now about 30 years old.
Always diagnose first before replacing.
Rarely do we replace the C-4 control head, (unlike the c-5) with most problems of failure to direct traced back to vacuum lines or programmer connections, then the programmer itself.
Take your time and check carefully and you will soon have full control of your HVAC.

Marty

[davidijaxson]

I have a similar issue but is also affects the cruise control.

[CamP]

Originally Posted by davidijaxson

I have a similar issue but is also affects the cruise control.

I've read that if both the cruise control doesn't work and the dash vents don't blow, the cause is either the vacuum check valve under the plenum is bad or the vacuum line to it is disconnected. Both use a common vacuum line that originates on the right side of the plenum.