FINALLY....2015 ....figured out this problem! It was the evaporator temp sensor. Remember, the issue was cycling on off, without allowing the compressor to run long enough to do any good. The compressor NEVER turned on when it was cool , or cold out, so I didn't have the defrost/defog action. Now on HOT days, the compressor would turn on, but not run sufficiently long enough.

 

  After lot's of tinkering over the past few years, evacuation, recharge, new dryer, new high pressure sensor, it came down to the evaporator sensor. (Obviously sensing colder evaporator temps than what actually existed).  I was taking out the fan motor to clean out the leafs such that managed to get in there and I decided to play with this sensor. I unplugged it and jumped the thing and damned if the compressor STAYED ON!!! The air got ice cold! So I cut the 2 sensor wires and connected them together. Now I have my air back after YEARS! LOL  It was the probe in the evaporator. Now I will get a replacement.

 

 Feeling happy! 

Funny you mention that because there's a thread here started just a few days ago with that switch in question. Can you see where the temp probe is inside the air box?

  No. I cannot see it in the box.....just the wire going into the box. In my case, I just "cut" the wire and spliced the 2 ends together. I now have constant compressor operation, but I have to turn it off occasionally manually to keep it from freezing up. I believe that I can get a new probe and fish it into the box and then see how it operates. It may not have contact with the evap core, but it may still work. Otherwise, I will have to split the case.