There are several reasons why a three-ton air conditioner won’t actually provide three tons of cooling, beginning with the clarification that three tons doesn’t represent weight but rather cooling capacity. This article will provide three explanations as to why a three-ton unit, or any other unit really, may not be providing exactly as much cooling as you think it is, even when installed perfectly. The first reason is something called nominal vs. actual capacity. The usual number you hear attached to a unit is its nominal capacity, but the nominal rating doesn’t necessarily come from the unit working under typical operating conditions as specified by the AHRI.
Read the full article here: A 3-Ton Air Conditioner Will Rarely Give You 3 Tons of Cooling