Ok we have a Carrier WeatherMate 8000. The fan is blowing air but its not cool at all. We set the thermostat at 74 and it never gets below 80. Any suggestions

1st with everything turned on go outside and see if the condenser unit is running. While there feel the 3/4 " copper line and see if its cold and the smaller 3/8" line should warm to the touch.(this tell you if compressor is running)
2nd make sure the filter is clean ,You should inspect and clean out the fines of the condenser and evaporater coils. After you`ve done these things you should see a big difference in the cold air temps coming from the supple vents,, you might want to get a thermometer and tell us the temp. of air coming out at the supply vents,, Let us know what you find