Big enough? Probably not. Cooling capacity is determined by the condensing unit, so you have a nominal 1-1/2 tons, or 18,000 btu. That probably works out to about a 75% sensible ratio or about 13,500 btuh.
To determine actual cooling requirements a cooling load calculation must be performed. Several forum members have found free on-line cooling load programs which you might consider.
To throw out some arbitrary ballpark numbers for your consideration:
Lighting load - 1080 sq. ft. x 2 watts per ft. x 3.42 btu/watt = 7387 btuh
Roof load - 1080 sq. ft. x .05u x 22 = 1188 btuh
Garage door - 112 sq. ft. x .9u x 22 = 2218 btuh
These three sensible cooling numbers total equals 10,793 btuh, and we haven't included any solar load, walls, infiltration, equipment, occupants, etc. Bear in mind the above numbers are pure guesswork and likely are not exact for your application.
Looked at from another direction, you have about 720 sq. ft. per ton of cooling. Here again that "ballpark" number is pretty high, depending on what your indoor/outdoor conditions are.
Do some research on line for a more definitive answer. Hope this helps.
As always, offered only as opinion
