That is the secoundary (overflow) condensate drain for your ac. Remove the metal door to access the ac above. You can clearly see the two drain lines,the primary line that needs clearing run's to shower drain vent.

I get the feeling they don't understand your answer (due to the post on HVAC forum) even though it is good advice.

Chama, there are two drains coming from your HVAC unit for condensate. The primary drain is normally used and drains somewhere not visible. The secondary drain drains somewhere visible in the case that the first one gets clogged so that you notice there is a problem. You need to unclog the primary drain or hire someone to come out and do it.

definitely want a water restoration company to take a look at that for sure. Don't want mold. I would know I own plumbersofhollywood.com

What we've learned here is that PoH's owner lacks integrity as well as the ability to read, comprehend, and make relevant recommendations, and that the OP needs to clear a condensate drain.

So out of curiosity I have kinda the same problem but not quite ?What does the side opening near your pipe open up to because mine is leaking but I live in upstairs apartment ?