My approach to AC problems is always "back to basics", which means first of all testing the system for leaks, proper pressure and proper amount of refrigerant and proper AC compressor clutch operation. Once the mechanicals are checked, then you can go into the fancier electronics. If your compressor is cycling on and off, for instance, that would give you the symptoms, and suggest low freon (maybe). I can't tell if you have automatic or manual AC/Heat control but if electronic then yeah, the control module could be failing to send the right signal to the compressor to switch on.
Having the control module fail so quickly suggests that maybe it wasn't the problem in the first place. Are you going to a well-trained AC specialist? A regular shop can't often deal with anything beyond the basics.