Air Conditioning - A/C not working!

When we turn our air conditioner on you can feel cold air coming out of the vents, but it is not strong and the temperature in the house never changes. We had someone look at it and at first they said we have too much freon so that must be the problem. But it worked fine last summer and we haven't added any freon since then. So then they suggested we clean our ducts. It just sounds like guess work. We vaccuumed them ourselves with a shop vac and it didn't help. They also had someone come out and give us an estimate on a new furnace and coils. They are 20 years old, but I'm hesitant to buy a new unit if it's fixable. They never said what was wrong with it. Also, he said if we get a new furnace we'll also have to get a new compresser (the thing outside?). Does that sound right? The compresser is 10 years old. We live in an upstairs condo that is about 1200 square feet. Please help!

The first things. Is the filter clean?? The blower wheel clean??? The inside coil clean??? I take it no ice or frost on the copper lines . Id check all the above first.

20 years old is old for a unit. Also the new units have a much higher SEER on the AC and AFUE of 80% and 92% on the furnace. Now if you have to change the outside unit yes you have to change the indoor coil also.

ED;)

Everything is clean and there is no frost on the lines. So, if they don't find anything "broken," but it still doesn't work does that mean we need to replace it? I'm frustrated that they can't actually tell us what is wrong. You said if we replace the outside unit we have to replace the coils too. If we replace the coils do we also have to replace the outside unit? Thanks for your help!

It is best if the outside and the inside units match. also at this time and 20 years old change it all furnace and AC. You can get a much better seer and on the furnace A better AFUE .this will save you $$$$. Also if you get it all new you can get a 10 year warranty on it . Get 3 bids for the job.

ED;)