My Lennox HP29-030-1P AC keeps shutting off the cooling and repairman is lost for answers. They've been out 5x's, pressures are normal. Some days the system will cool for 12 hours and other days under 2 hours. I;ll turn off system and let compressor cool and then it will turn back on. Techincan has never seen this problem. They called Lennox but they said they didnt know. Curious, can you replace the thermocoupler on the compressor (just a guess that's the problem)? What else could be wrong?