Wedge a couple of manila envelopes over the vent. In one of the last places I worked, the air conditioning vent was directly above me and pumped out arctic air all day. I couldn’t control the temperature, so I blocked the flow of air. It was much better.
Are there no controls on the air conditioner itself?
Sometimes they get real stupid about thermostats.
In the middle of winter in the truck gate, they had the Heat and A/C settings TWO DEGREES apart. And the system wouldn’t heat it to 70 and then stop. No, it heated to 72 and then stopped because then it had a bit to cool off before it needed to kick in again. Only problem was that the heat would turn off, and immediately the AC would kick in and cool it down to 70. Heat to 72, Cool to 70. Endless repeat. When it was 30 degrees outside. One of my guys broke into the box and figured out how to reprogram it, and we set the two systems to 68 and 75 so that wouldn’t happen anymore.
A couple of days later, client boss strolls through the gate (which he only did about once a month) checks the thermostat and notices the box is not locked anymore. Blah blah blah threats, blah blah blah anger, blah blah blah more threats. I explained to him what had been happening, how much money it was costing them to have the heating and AC battling each other 24 hours a day, and pointed out that the current settings were reasonable. He calmed down and agreed with me.
furryman, for what it’s worth very few people have any control over the temperature of their work environment. It’s a huge pet peeve of mine that I freeze all summer and roast all winter. IMO it should pretty much be 70 degrees all the time. The point of HVAC is to make the environment comfortable, not to make the indoor temperature inversely proportional to the outdoor temperature.
DianaG, this is the most sane thing I’ve ever read concerning HVAC. If I gave you a list of employers and my husband, could you please inform them? You say it much nicer than I would. My way would involve a lot of swearing and throwing of things. 
Doubt this will work for the OP since he’s dealing with an AC unit, but for those who suffer from locked thermostats…bring a couple of ice packs to work, place them over the thermostat box so the temp goes down and causes sweet, sweet heat to vent out. Repeat as needed.
OP, maybe get a space heater - $35 on Amazon. Portable, and no one has to know!
This is what I did. Now I’m waiting for somebody to complain about it.
Dear Cimera: I’m already aware that I’m a total loser. Thanks for rubbing it in. But no matter how bad I am I can rest assured that you’re an even bigger loser than I am. At least I don’t go around insulting people.
Unless it’s steaming or freezing outside, I hate A/C.
Except you just did. And totally distorted what I said in the process.
Don’t take it personally. He’s got a bit of a big head because he managed to leave mundane security work behind and make it big in the glamorous, highly rewarding and lucrative world of customer service.
I gave four options.
1> Student doing it for money while working on something better.
2> More or less chosen field.
3> Loser
4> Just passin’ through.
And guess which one he chose.
For those suggesting a sweater: I’m sure it’s the same everywhere (like most laws) but in Texas it’s illegal for a uniformed security guard to cover up their patch or their “badge” (in Texas if you’re wearing something like a roadguard vest it is allowed to cover the badge but not the patch). This is why the companys usually issue a jacket or windjacket with the patch and badge on them. Also, it likely a fireable offence to be out of uniform when on duty. I know for my company it is.
And he seems a bit prickly about it, too. 
I agree with DianaG - I’ve worked in every size of company, and the one thing they seem to have in common is that you are NEVER working at a comfortable temperature consistently. Either you work in an office tower where the temperatures are controlled by some automated system that always gets it wrong, or you work in an area where the temperature is controlled by women who are always freezing even at 85º, or are menopausal and change the thermostat settings every time they have a hot flash. Or both. Or some combination I haven’t thought of. All you can do is dress in layers. Lots of layers.
ETA: Forgot about the vents - the rest of the office is comfortable, but you’re sitting right under a vent and just about have icicles hanging off of your nose.