Air Conditioning - house not cooilng

Houston, Tx
This is a house my fiance and I are wanting to buy except there is a problem with the house, it doesnt cool down.
the house was built in 2008 but never lived in.
1677sqft, 1 story, has all double pane windows, lots of loose fill insulation in attic, no blinds.
Carrier condenser, r-410a, the inspector said 30,000 btu's, I dont know what that means. Honeywell digital thermostat.

95 degreesF outside, full sun, no shade trees. inside temp was 92degrees, I set the thermostat to 70degrees and after 3 hours, it got dark already outside already, the house only cooled to 82degrees. when i put a thermometer up to the vent it says 74, at the return vent it says 80. also the air coming out of the vents seems to come out slow, like not very much pressure. the house that i live in now, the air blows hard out of the vents...

what could the problem be? low freon? bad compressor?

thanks for comments and suggestions...

low air flow could be leaking ducts, dirty filter, the poor temp issue could be the return duct is sucking in hot air in the attic, low freon, bad compressor- many items need checking. 30,000btu's means it's 2-1/2 tons. Is all of the 1677 sq. ft. air conditioned space? In Houston 2-1/2 tons is a stretch on a house that size unless it is very well insulated, great windows, etc. One thing you need to realize is a house that is sitting with the air off in the kind of heat Houston is having now will be HOT. What I mean is the structure has to be cooled down as well as the interior. That could take 1 or 2 days, however the 6 degree TD you have from supply to return is a red flag. If you're serious about this house, go here and do your own heat/cool profile.

HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations (http://www.hvaccomputer.com/)

It might be $50 well spent.

Could very well be as simple as blocked air filters. If they ran the system during construction ie: drywalling, painting, etc the coil may be blocked as well. I agree, 2 1/2 tons sounds light but you would have to do a load calc. And "DJ" is right, it may take a couple of days to pull the whole house down.

Have the builder get the unit serviced:thumbup:

I'm in San Antonio and a rule of thumb for this area is one ton per 500 sf. Tall ceilings or heavy sun on windows would inch that up. One ton is 12000 btu. So 1677/500 = 3.4 tons = 41000 btu. You should have a 3.5 ton. I used to have a house sized at 1650, had a 3.5 ton, but eventually went to a 4.0 ton cause I had no shade and it just baked.