I have a Goodman a/c unit that is about 9 yrs old. It's a 10 seer "builders quality" unit is what I'm told. Recently (two weeks ago) just had the a-coil replaced and they had to use a 13 seer model and use a converter to get it to run at 10 . Can't replace with a 10 seer since 13 is the requirement for our area now (oklahoma).

Yesterday the a/c unit ran outside for 9 hours trying to keep us cool and the thermostat stayed at 77, but we had it at 74. Questions:

1) The two lines going in and out of the a/c unit. One is 2~3 larger in diameter than the other. The smaller one was HOT should it be? The larger one was cool.
2) Typically the a/c unit should not run 9 hours straight right? Ran from 2pm to 10:30 pm to drop the house (1300sq ft) from 77 to 74.
3) It only got to 88~90 degrees yesterday and we did have people going in and out of the house with the oven on. Still think it should cool from past experience and not run so long.
4) Any comments on the Goodman brand.. I wonder if my a/c unit is now going out.
5) I checked the registers with and one gave 70 degree a/c during the heat of the day, but in the evening it dropped to 62 degrees. What should I expect those to be (I couldn't find this in the FAQ).

Any other tips before I cann out the a/c guys again to look at it so I'm a more informered consumer? Hope all had a great 4th!:)

Thanks...

OK here is the deal.

First off they should have put in a expansion valve when they replaced the coil. If they did not do this there will be cooling problems since a 13 SEER coil has a larger coil surface that a 10 SEER one.
They might have just used the flow rater that was in the old coil or they might have used the flow rater that came with the new coil but they will not work properly. You need an expansion valve.

Next. Make sure the outside coil is clean. A back flush from the inside of the coil to the outside is the best way to do it.

Next make sure they check both the superheat and subcooling of the system so they know exactly what is happening. If they do not know what super heat and subcooling is then they should not be in the HVAC business.

Next. There should be a 18 to 20 degree differential between the return air and the supply air. This is a standard temp drop for all A/C units. (rule of thumb).

Next. Goodman brand is just as good as many others. What makes one unit better than another can be the install. If the unit is not installed correctly it will have more problems.