Just had my '04 Z71 Avalanche in due to very rough idle and had the drivers
upstream O2 sensor replaced. The tech told me he pulled a B0229 and B7770
code at the same time when diagnosing the rough idle. I know the B0229 is
HVAC recirc actuator code but what the heck is B7770? The HVAC was working
fine when I took it in to be fixed. Now I can't turn on AC, light just
flashes, and the system will just blow defrost or floor with no a/c on
defrost.
So, please, my question is what's the B7770 code ?
Could this in any way be related to the what the tech did repairing the O2
sensor? He said they had to reflash the PCM after installing the o2 sensor
and have the truck relearn it's parameters.

Thanks