Automotive A/C question

[plthijinx]

2001 Ford F-150 4.2L engine (6 banger gas saver) anyway when i bought it last year the ac worked fine. this summer? hellnaw. houston with no ac is like roasting your balls with a bic lighter. anyway i went to add freon and the system will not take anymore. the compressor has a 2 second cycle. on for 2 off for 2. you get the idea. anyway my question is this: would a clogged orifice tube cause this? when i was trying to add the can of freon the gauge would get close to the red then the compressor would kick off and pressure would drop to the lower green arc. i'm a little baffled and don't have very much ac experience. any pointers are greatly appreciated. thanks!