I have a new home that was built in early 2007. The Heat and cooling system that was used by our builder is a Goodman CPLT36-1B. This is the outside unit. When we moved into our home last June I asked the home inspector if this was a large enough unit. He told me that it was "enough".
Here's the issue. Our home is a 1 story with bonus room. The unit is setup with two thermostats (1 on the first level and 1 in the bonus room). The unit ran great all-be-it all the time, it would heat and cool the home. Our electric bills are in the 270 range. We conserve everywhere we can but when I run the A/C or Heat the bill really goes up. We are located in central North Carolina. Our home is 2130 sqft.
I went to a neighbors (exact same home - same builder) and their unit is much larger. It is a Goodman GSH130481AA.
Here's the kicker! - Our unit has failed! The compressor thumps like it is trying to start and then nothing. The fan blows but nothing else is working.
I am of the opinion that the builder was trying to cut corners and the sub contractor used a smaller unit then should have been installed. I need to know if this is correct. It is being repaired at no cost to us. I need to know if they use the same size unit (and I think that is what was ordered) am I going to have the same issue in a another year?
Please give me your best advise here. I am learning as fast as I can about this stuff but those installers and contractors really "fast talk" and I think I might be getting the short end of the stick. I am a retired Marine and we saved a long time to get this - our first real home - and I want to get what I should.
Thanks in advance.
John

3 ton a/c seems small to me also for that size a house,, would have to be extra tight everything in the window and insulation department, does it or did it run a lot,to get the tstat satisfied to turn itself off?

The unit would run virtually all the time. It would move the temp inside the home toward the desired direction but until the outside temp dropped in the evening the unit would run.

It's undersized if it never reached set point. Correctly sizing an AC helps control humidity. Oversizing (poor humidity control) is bad as well as undersizing (poor comfort).

Make them replace with the right size,instead of fixing something that is to small

Ask for the manual J (sizing) and manual D (duct design) calculations.

I will ask for those items. That is a great point. I can speculate all day but that should resolve it. Thanks.