Our home AC condenser fan broke. Due to it's age we elected to go ahead & buy a whole new condenser. The old condenser had a copeland compressor model# CR30K6-PFV-260 with a capacity of 24300 btu/h to 30000 btu/h based on the 50 Hz or 60 Hz frequency (I think it was 60Hz - have to chk jpegs). The label on the old Intertherm condenser was worn away. Hutchinson HVAC contractor looked at the old compressor model # and said the condenser was a 2-1/2 ton.
The new 2-1/2 ton Goodman GSC130301 condenser has a copeland compressor model #CR23K7-PFV-230 with a capacity of 22600 btu/h... it's now hard to get the thermostat temp below 74 degrees F... even after Hutchinson added another pound of refrigerant... will try a good 5 hour run tonight... I'm inclined to say the compressor is too small right - it should at least match the old one or be 30,000 btu/h capacity to service 2.5 tons of load right? Are the manufacturers throwing smaller capacity compressors into the condensers these days? What can be done to improve this unit's performance?

First of all you just do not add one pound of refrigerant to anything unless a super heat or subcooling calculation was done. Which probably was not done to start with.

NOTE when you replace the outside unit you also need to replace the inside coil since the total SEER efficiency and output in BTU'S depends upon both items being replaced since that is how it is tested.

Now as far as the old being 24,300 as compared to the new at 22,600 is really no big deal at all.

At this point I believe something is incorrect with the install. Was the metering device piston/expansion valve/cap tubes replaced on the old coil to help match the outside to the inside? Probably not!

I would recommend you install the correct new inside coil to match the new unit outside.

Yes,they are using smaller rated compressors in the outside unit and they perform just like the old ones if proper attention is paid during install. Like a matching indoor coil and a matching refrigerant flow device like the piston/expansion valve.

You need to find someone who really knows what they are doing with a mismatched system.

Good luck.