Everything worked fine with the A/C on our 2000 C5 (in fact, would freeze you out) until today. We drove about 7 miles. Parked. Got back in to come home and the A/C was barely coming out of the main vents, but was blowing out at defroster and feet. Another poster had the same problem on his 2000 and described it better than I:
"When I turn on the a/c (high) the majority of the air flow (warm) is coming from the defrost vent, some from the passenger side vents and hardly any from the driver's side vents."

My best guess is something wrong with the actuator switch, but keep getting a "BO338 H C" code. Have gone through the clearing process ~20 times. We can hear the actuators running when we do this, yet keep getting the BO338 H C code.

We found the info on how to reset the HVAC by pulling the #27 fuse for a minimum of 60 seconds. Another poster suggested 30 minutes was more realistic. That didn't work either.

I am beginning to suspect bad vacuum lines, but have no idea where to start.

The above poster mentioned battery acid leaking on the line... is that the only vacuum line for the actuators?

HELP! We are supposed to leave in two days on a multi-state trip.

 

The B0338 code has nothing to do with the actuators which are electrically operated. They control air temperature and have nothing to do with which vents are used. The code is for the inside air temp sensor located behind the little grill beside the ignition switch. I doubt (but it might) if this would affect air flow but it should be checked and replaced (inexpensive part) if defective. The codes says it is an open so check the wiring and connector. Air flow out the vents is controlled by vacuum so there could be a problem there but fix the sensor problem first and see if it helps. Fixing the vacuum line will be more involved.

 

There is a single very small black plastic line that provides vacuum for HVAC vent control.

Here are some links to review.

https://www.corvetteforum.com/forums...with-pics.html

https://www.corvetteforum.com/forums...cuum-line.html

https://www.corvetteforum.com/forums...diagnosis.html


Mr. Sam

 

In the service manual there is a very good description on how to check the sensor. If you can use a DMM it is very easy to check, only 9 steps. Perhaps someone with an online manual could send you the diagnostics.


This information is from my 1999 manual. There is a description there on using a DMM to do the tests instead of the GM scan tool as referenced in the diagnostics posted by Mr. Sam. I see that the OP has a 2000 so a scan tool may indeed be needed.

 

Here are the diagnostics for B0338:

https://www.dropbox.com/s/wlxdo69r3b...B0338.pdf?dl=0


Mr. Sam

 

Thanks everyone for the quick answers. I spoke with the shop where we bought it... the previous owner had removed the sensor to install a hands-free phone. okay... whatever.

Anyway, the problem IS a vacuum line and will be fixed by tomorrow!

Again... thanks everyone!