I replaced my 4 ton 13 seer american standard outside unit with a 13 seer 4 ton goodman.. the compressor was shot and the unit gave me nothing but problems.. the ac man I hired is very reputable and was highly recommended.he told me I have a trane air handler and it was not a problem matching it with the goodman... everything is fine,house seems to cool nicely until the temperature outside gets into the mid to upper 90's.. I live in n.florida and it gets pretty hot in the summer... I set my thermostat in my house @ 78 in the middle of the day,and the temp in the house at the thermostat will read 80.. also in the winter I will set the heat at 68 with temp outside in the 20's and the temp in the house will be 62-63... he says that is normal... does not sound right to me... thanks..

Some thermostats are more accurate than others.

Some thermostat installs are in better locations than others. One trick to help make sure the thermostat is as accurate as possible is to plug the hole where the thermostat wires come from inside the wall to the thermostat. The hole if left open will allow air that is inside the wall cavity to control the temperature instead of the air within the home. This can make a big difference and it is often overlooked by both home owners and professionals alike.

Thanks,I looked at that and it was fine... my thermostat is located in an area that does not get sun light.. or light from light bulb or any other source..