Gas and Oil Home Heating Furnaces - Drain line clogged

Bear with me for I am not very HVAC literate. I have a furnace/ac unit in my garage. It has a big grey box with a foam insulated line running into the top of it and a bare 3/4" pvc pipe running out of it. I have cold water leaking from the pvc pipe at the juncture with the box. I suspect this is the drainage line (?) and that it is clogged up since the water appears backed up in the bottom of the big insulated grey box.

Any ideas on how to clear the drainage pipe? It has a number of sharp 90 degree bends that make it a bit difficult to work with. Would you suggest algaecide, bleach or a water hose to flush it out?

Too many 90 dgree bends can cause problems. How about a shopvac on the discharge end and see if you can suck anything out? You might try the shopvac at the origin, if you can get it in there. 90 degree bends will make snaking it out difficult. You might try that where you can. PVC is pretty tough, so most any kind of stiff wire might help where you can reach.

If it is blocked, I would be reluctant to put anything into the line that would cause a problem if it spilled or you had to remove it. If it is blocked and you run water from a garden hose into it, you might wind up with quite a mess if it blows back.

I find most of the time with stopped up drans on AC. We carry a short length of vinyl hose that fits in the 3/4 pvc pipe. slip it in and just blow back hard then look out cause here comes the yuck.If this dont work also have 3/4" PVC couplings cut the pipe some where near the unit and blow both ways. after that then a little bleach.;) ED

Thanks for the advice. I used a high pressure nozzle on my garden hose which successfully dislodged the clog...without an unsightly backup. Everything is flowing freely now.