I'm Working on a Lennox split system unit With an intermitting problem. First time I got called, the unit was operating properly.Two days later I get called again, I connected my gages and the suction kept sucking down below 50 psi and the high side went up to 400 Psi and kept climbing. So I shut the unit down, the compressor would of went out on over load any way. Went to check if I had air flow, That was ok went out side to turn the unit back on And the unit started working properly again. Can't find any thing wrong.I know there going to call me out again. Any suggestions Thank you in addvance.