Just asking the obvious...what kind of thermostat do you have? If it is programmable, how is the program set?

It is programmable. I have verified that it is not the thermostat. I changed the thermostat but also, our thermostat is usually on hold to maintain the same temp. Also at the advice of someone ( I can't remember exactly what I did at the time) but I shorted , If I remember correctly, R G and Y on the thermostat at night. Same thing, fan only ran.

Is this a heatpump?

Have you checked to see if there is ice forming on the inside coil at night?

It is not a heat pump, and no I have not checked for ice at night. I'll do that in a bit.

jtw

a nice anecdotal story with few facts.

let's get some specifics.

your location?

brand, mdl, age, size of existing system?

amount of living area unit serves?

home is sgl story or two story?

location of ductwork?

thermostat setting?

average high outside temperature?

insulation qualities of home?

filters regularly changed?

last time system was service?

any idea of supply temperature? if not, find out with dig thermometer. how about return temperature? if not find out.

why accept this situation without an experienced HVAC pro checking your system out?

IMO

So your having a problem with your unit for a few years and haven't called anyone out? unbelievable. Your compressor sounds like its overloading. keep on running it and soon it will go poof. Up in smoke.