Air Conditioning - Air Conditioning won't turn on

Yesterday I noticed there was a leak in the hallway coming from the ceiling and baseboard. I determined that the drain line was clogged for obvious reasons. At that time the air conditioning was running fine despite the leak. I turned the air conditioning off and used an air compressor to blow into the tube. That cleared it as a bunch of gunk came flying out of it and the leak stopped. I left the air off for a while to let it dry out up there which it did. However, when I turned the air conditioning back on it didn't cut on. There is a little click at the control box but the inside unit nor the outside unit turn on. Nothing is running. I turned all the circuits off and back on and still nothing. Any ideas? Your assistance would be greatly appreciated.

Never mind, I solved the problem. It was the overflow valve on the drain. Evidently when I put air in the hose it caused it to stick in the full position which prevents the air conditioner from running.

Why didn't the switch turn off your a/c when the drain was clogged and leaking on your ceiling? Where is it positioned?

It is at the top of an L shaped piece of PVC coming out of the unit. Part of the problem I think and hopefully you can answer this is that there is no pan underneath the unit. There are two pvc pipes coming out of the unit. One with the shutoff switch and one going to the drain pipe. I spoke too soon when I said it was fixed. Yesterday it started leaking through the wall and ceiling again. This time I put bleach in both pipes in the attic and blew them with an air compressor down this time. A lot of gunk came out again. The unit continues to work fine, however, there is condensation all over the bottom of the unit again and some ice as well. It is not leaking down as of yet like it was before. The other factor is that the filter was really dirty and I changed that out yesterday. Might it be that there is still a lot of humidity and with the new filter it will correct itself or do I have another problem. Also are there certain units that do not require a pan outside of the unit itself or is mine just rigged. Again, any help would be greatly appreciated.

It sounds like you're saying that the air handler is mounted/hanging horizontally in the attic? Thats what mattison was asking, not the position of the overflow shutoff. Normally, units installed in the attic like that have a secondary catch pan under the unit which has it's drain line piped to the ouside near a window that you look out of all the time [like a kitchen window at the sink]. If you see water running out of that pipe, you know there's a problem. Make sense?

You really should have the secondary pan under the airhandler. What you have will only work if the main drain is cloged it sounds like.

Now you said you had some ice. The new filter may cure that if not you will probably need to get in there and clean the coil up in the attic.