What is the temperature of the air coming out of a central air unit suppose to be if the unit is cooling?

Question

If the temperature outside is 96 degrees and my house is 79 degrees in one of its cooler areas (86 degrees in it's hottest) shouldn't my house be cooler? The air going in to my unit is 79 degrees where my thermostat is and the air coming out is 66.4 degrees shouldn't the air be cooler? Is my unit charged enough? I had someone service i and said it was charged enough. It is blowing air just fine, it's just not cold enough.

Answer 1

If your AC is sized correctly and running correctly there should be about 20 degrees difference between return air temp and supply air temp on a "design" day.  "Design" day outside temperature varies by location but 96 is pretty good for most of the US. If the air is being returned from an 86 degree area the unit itself is probably working OK (86-20=66).  If it is being returned near the thermostat it may be functioning less than optimally. (79-20=59)

My guess is that you have a combination of things going on.  The unit may be a little small due to an original error in sizing or you building envelope may have changed.  It may not be operating optimally due to refrigerant problems, low air flow cause by filter or dirty coil problems.  

In any case the tech should be able to figure this out.