Hi. I'm Joe and I will be glad to help you out.
I read your other question and I should be able to help you out with it.
If you have a shop vac, you can find the drains where they terminate outside and hook the shop vac there. It should pull the clog out, then the water in the line should run out.
It would be easier to do that than cutting the line and blowing it out.
It is normal for the drain pan to be set up like yours. The pan under the unit is an emergency pan and should only get water in it when there's a problem with the other drain. If you suck out all of the water that you can from the drain lines, the leftover water in the pan should evaporate within a few days.
what kind of Shop vac, could you tell me a bit more about its specs, there are so many different ones out there. In addition, where to get an adaptor in order to properly connect the vac outlet and the pvc pipe?
Pretty much any shop vac will work. I use a small 2 gallon one because it's easy to haul around. If you get some painters tape, you can seal the shop vac hose to the pvc line and the tape will come off easily. If you would rather make an adapter, you would have to put one together with pvc just to fit over a 3/4 inch pvc line.
Usually what would you see in the shop vac after you vac the pipe?
The pipe extends from the AC unit in the attic all the way to the bottom of the wall outside the house, I guess you really need a strong suckre to get those stuff out.
Is there anything I need to pay special attention to? Sure need to turn off the unit, but what else? Souds like pretty simple, just hook up and suck. This save a lot of effort that would need to work in the attic.