I have an 1800 sq ft ranch in New Jersey built in 1960. Unfinished attic has about 8" insulation and windows are newer thermopane but I am not sure if walls are insulated. Has a fair amount of large windows. It sits mostly over a full basement with two foundation walls exposed (walk out). Has forced air heat with 3 ton air handler. Central a/c (3 ton) is run through the heating ducts as well. Furnace is 18 years old and a/c is 16, both are Carrier. I am having difficulty cooling the house this year. Air temp just above evaporator coils is around 60 degrees, tech says should be closer to 50. Tech says refrigerant is good and rest of systems checks out but compressor line pressure is high and is running hot. One of the issues is that air flow at supply registers is weak and I don't see how it can keep the house cool in 95 degree weather. I took the air filter out temporarily but it didn't seem to make a difference. I am running a couple of vortex fans in front of registers to help distribute air up and across the rooms. Blower in furnace seems to be fine. I am going to replace the a/c and possibly furnace as well. Tech says to upgrade to 4 ton air-handler to increase duct pressure. Does this seem like too much for 1800 sq ft?