With all this discussion about A/Cs I though I'd through my "problem" out there. Five year old 1-story house with air handler in a closet (not in attic). It seems the air handler is sweating right above the motor/furnace/drain line area. There looks to be a taped seam right in the same area. I change the filter regularly and put a less restrictive filter in this last time, but still seems to be sweating. The closet door is pretty tight and may not let a lot of cooled air inside. I am in central Texas (humid) and wondering if it is just too warm/humid in the closet and if there is really anything I can do about it other than leaving the door open? Kind of sounds like the other guy with the sweating drain line under the sink.

Any ideas are welcomed. TIA

I just went through this. My issue was the primary drain pan inside the air handler was cracked so water leaked all inside the air handler and the insualtion inside soaked it up like a sponge causing the entire handler to sweat/drip. I just had it fixed yesterday so I'm hoping we don't run into any more issues in the near future.

Ac systems sweat for the same reason your glass does when you have your margarita sitting on the table and your wife yells at you to use a coaster......

Anyway...sweating is normal....the root cause may not be. See if that taped area is leaking cold air. If it's not, sometimes it's just tho cold water in the condensate line that drops the dewpoint locally and it sweats.

Either way....there are worse problems to have.

Check return air and try to open additional opening if possible. If CFM is not where it needs to be the coil will be colder than it should be and sweat. Also check the top of the closet and seal everything off except the opening for combustion air can sometime create warmer environment in the closet due to attic air leaking in.