There is a very good chance your drip pan is full of water because your drain line has clogged.

In two story residential units, they will install a primary and a secondary drain line for both units. The primary drain line goes right by the outside unit. It is made to just drip into the grass and basically be invisible.

They then put a secondary drain line in a place that will be visible, typically a back patio. Those drain lines should never drip. If they drip, you have a problem with the primary drain, and if your drip pan fills up and the float hits the catch, voila suddenly all you have is fan but no actual air conditioning.

It happens routinely because of the growth of mold. There are preventive measures, like periodically pouring a bit of bleach down your primary drain line to ensure that mold doesn't grow.

Check the drain lines. It is not a hard thing to fix if that's the issue. If you have a Shop-Vac, you can purge your drain lines.

Good luck.