Outdoor a/c unit makes 1 second long buzzing noise.

[bedmonson]

I'm still getting cold air inside and the fan on the unit is still working, blowing hot air. I read in a previous thread this may be the contactor failing. Same issue?

[Ken]

I do not know about your noise, but I can tell you I have had problems with ants being attracted to the A/C hum of the contactor coil. When it closes it insulates the contacts or causes an arcing across them. The solution for me was to get a contactor with sealed contacts. You might look at the contactor to see if yours is open.

[trader_4]

When does it make this noise? When starting? If so, sounds like it could be the contactor. Removing a cover and isolating the noise would tell you.