Check Engine P0134 & A/C outage

[VolvoKev]

I'm trying to get some clarity on my check engine light. The P0134 leads me back to the O2 sensor 1 Bank 1. At the same time, my A/C has gone out, and even the vent fan seems slow to start up. I may be seeing things, but even the headlights seemed a bit dim when driving home tonight. I could simply change out the 02 sensor but wanted to see if anyone here had a suggestion, being that that wouldn't cause the A/C issue.