I have a lennox model 13hpd 036 230 01, S/N 5807m06629 and today I noticed my unit wasn't blowing cold air. The air handler works but the outside compressor doesn't turn on and the fan doesn't spin. Im not too knowledgeable in A/C but am handy and would like to see if I can diagnose it before having to pay another 200 for a HVAC to come out. Any help with this. Already check both breakers and spun the fan and it moves rather freely. I do however here a buzzing noise.