We have a new heat and A/C unit in the attic. Had it put in last fall. Turned the air conditioning on and after about 30 or 40 min. water starts leaking through the ceiling onto the floor below. The water is coming from the empty box like thing that is next to the evaporator (I hope I have that word right). We've looked at the pipes and none of them are leaking. Since the unit is new we don't expect that any pipes are clogged. This part of the unit has insulating material all around it. We can't get anyone out to look at the unit quickly... hard enough just to get someone to call us back... we are in a rural area. Is there anything we can do?

Try to free up the drain. It is probably plugged up. Gently back flush just a bit from the discharge end to the unit.

In a proper install a water switch should have been installed in that location and an overflow drain pan.

Thanks for quick response. The overflow pan is under the evaporator but not this part of the unit which is empty and directs the cold air to the trunks. To try and picture it, there is the blower, the evaporator and then the section that directs the air. You're saying that this part of the unit needs an overflow drain pan? Just to make sure I've included enough information.. . this part of the unit has insulation all around it and is where the water is dripping from. Insulation is now wet on the bottom.
Water switch: all the switches are 'on'. I don't know if one of them is called a 'water switch'. All help is appreciated.

Not being able to see its hard to say what to do,but it does sound like a drain line is stopped up,, I allways put evap coil ,furnace and all in a overflow drain pan, but the pan also needs a drain put in it to back up the main drain,, sounds like the installer needs to come back and maybe do his job over again

Here is a URL of an attic install gone wrong:

http://www.air-comfort-company.com/seeourwork.htmlhttp://www.air-comfort-company.com/seeourwork.html

Btu Buddy 28: A Stopped Up Condensate Line - Service and Maintenance - Extra Edition - Air Conditioning, Heating & Refrigeration NEWS (http://www.achrnews.com/Articles/Service_and_Maintenance/5efc6e506906a010VgnVCM100000f932a8c0____)

Maybe you can actually spot problems with your installation. Take a picture of yours and post using "go advanced".

Water is removed from the air with air conditioning and if the overflow pan ever gets water in it the unit should shut off because a sensitive switch (non-float style) should be installed in series with the thermostat contact going to the AC.

Such as this one:
Diversitech WS-1 Wet Switch Flood Detector: All Thermal Supply (http://allthermal.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=WS1&Category_Code=LITGAINT&Product_Count=0)

Brand new home & secondary drip line running again - HVAC-Talk: Heating, Air & Refrigeration Discussion (http://www.hvac-talk.com/vbb/showthread.php?t=148594&highlight=drip+pans)

Condensation is also produced when warm air hits a cold surface. Again pointing to an installation problem.

Here is a sweet installation:

http://www.polandhvac.com/images/FurnaceAtticInstall.jpeg

In any event, there is something wrong with the installation. All it takes is the wrong slope and water ends up somewhere where it isn't supposed to.

There are two basic sources of water:
1. Evaporator
2. Condensation from cold surfaces and warm attic

The drain does not have to be confined over a small section either.

Hope this helps.

Have read the links. Thanks for sending. We found a rip in the insulation on the area that leaked. The tear exposed that section to the hot air in the attic. We're rewrapping and taping.
No water in either drip pans, pipes leading out have been slanted down. Will check for stoppage in drain pipes also. Sweating like pigs but carrying on. Will post pic. If all fails -thanks for explain how to do this.

Here is the attachment with picture of the unit in the attic.

Resolution: The problem is being resolved slowly. The unit was not level. So even though the common answer to this problem has been 'clogged pipe' a unit that has not been leveled properly will not allow the condensed water to flow out through the pipes and out of the house. All of the pipes were dry right from the pan. It's a bad installation. We have had the installers come to the house and level unit. There has been no dripping water through ceiling for a few days but just checked the unit and the secondary pan is filling up with water and isn't letting the water flow out and down the pipes leading out of the house.
I figure the secondary pan shouldn't have any water in it at all.

Yep, secondary pan should have no water. It should be equipped with a water switch that prevents the AC from turning on if it does, so you'll investigate when you have no AC.

Final answer. Installers came back. Opened unit / evaporator. The first drip pan was cracked. Water was not being fed from this pan down the pipe and out of the house (for anyone who doesn't know this by now). Instead it was leaking into the secondary drip pan. They replaced the cracked drip pan and so far no problem. Also installers did put in a cut off switch for secondary drip pan - no cost. Thanks for all help and comments.