Here's the problem...

A/C has been serviced and is said to be in full working conditon... Furnace has been serviced and is said to be in full working condition... A/C worked fine last Summer.

Temp inside house was 79F this morning... turned on A/C... after running for a while Temperature in Vent closest to Furnace was 60F... Temp at Cold Air Return was 74F

Air is circulating through house constantly on a DC Blower... House just simply will not cool. Thermostat is a Programmable Digital about 5 Years old... wondering if this could be the problem. Windows and Doors are all 3 Years old and are Energy Saver style...

All Dampers on Upper levels have been opened, basement ones have been closed off...

A/C has been on for 3 hours now and temperature in house hasn't budged at all according to the thermostat...

Any Suggestions?

Your outside unit might not be working up to capacity. You said the A/C had been serviced. How come the A/C person did not fix this problem? How could they say it was in full working condition when it is not?

According to your post you have a 14 degree TD and that is a little low. Usually a 18 to 20 degree TD is more normal. I would suspect a dirty coil outside,a dirty coil inside, or the superheat or subcooling is not calculated correctly from the service that was performed.

You might contact the company that provided you with this service you talked about and have them recheck there work. They were the last company to work on your unit and it is not working correctly. I guess you paid them for there work so I would make sure they took care of a problem they should have found when they were there.

Sounds like it may be low on refrigerant charge with a 14 degree TD, should be about 20 degrees TD. Mike

I hear a echo here. LOL

If you had a dirty evap. Coil you would be seeing a greater differential of temperature(more then 20 degrees) across the coil due to the coil being restricted by the dirt and slowing down the airflow and increasing temp. differential , dirty condenser will increase suction pressure in a coil that does not have an expansion valve, you did not say how long it has been since you had it checked and if it was hot outside when it was checked,some service people don't pay close attention to the a/c during the winter, if it was resent they should recheck the system at their expense .Most reputable contractors will stand behind their work. Mike