Brad Kirby

I started off with hot air blowing from the driver side all of time and cold air from the passenger side all of the time. I could change the fan speed and turn the a/c on/off but I couldn't change the temperature. I read the following thread: http://www.digitalcorvettes.com/foru...=135883&page=5

I pulled these codes:
B0332 HC
B0337 HC
B0361 HC
B0365 HC

They are short to ground codes for the internal and external sensors as well as short to ground codes for the driver and passenger temperature doors.

I did the reset where you pull the #27 fuse for a minute. It ended up being pulled for a few minutes while I looked around for a persistent coolant leak. Note, the key wasn't in the ignition, the engine was off. I put the fuse back in and started the car. Immediately, all of the lights on the head unit started to flash. I can turn the a/c on/off by pushing the button, I can change the fan speed, and changing the temperature on the driver side (can't see what it is set at because of the flashing) yields an audible change in the vents which I think is the fresh air door changing position. I still have all hot air from the driver side and all cold air from the passenger side.

I pulled the codes again, in addition to the codes above I got two more:
B0441 HC
B0446 HC

I should also note that the heat worked fine until I had to unhook the battery for an hour. I used a memory saver that you plug into the OBD2 port and an external battery to keep the memory settings in the PCM.

I need help, I need all of the help.

Bill Curlee

What is the status of your battery????

Hook a DC Volt meter to the battery main terminals with the battery connected and under load (ENGINE OFF) and report voltages.

Report voltages with engine running.

SG Lou

Low battery voltage / amps will cause many strange things to happen to your C5. Like Bill said, Check battery first !

Brad Kirby

I observed the voltage all day today and yesterday before I reset the HVAC. I haven't tested the voltage with the car off, I'll do that after I finish fixing my air compressor. But, engine on and warm with all lights on, 13.4, engine on and warm lights off, 13.6. Cold engine no lights, 14.4. I noticed the grounds under the hood were repaired by the previous owner. The connections look good and I don't see any corrosion under the ring terminals.

Brad Kirby

Found coolant leaking out of the heater core drain. I can only imagine this has something to do with the HVAC issue, but doesn't really explain all the short to ground codes. Looks like I'll be changing this to all makes green coolant, not the first (or 100th) time I've seen DexCool kill a heater core early.

Brad Kirby

Since I have to completely disassemble the dash, is there a way to test the swing doors operation while I have it apart? Also, if someone with a manual could point out where those grounds are (for the air temp sensors and the swing doors) so I can freshen them up, that would be excellent. I need to order a set of FSM's if anyone has a line on them or a set for sale.

I may just bypass the core for now and wait for a sunny day to do this all outside instead of my cramped garage. It would also give me good light to do a video of this so the next poor soul will have an easier time replacing the heater core.