TT: Customer complaint of HVAC compressor ?Bang? type noise upon initial compressor engagement when air conditioning has not been operated for an extended period (~24 hrs. or longer).
The noise is caused by compressor oil collecting in the compressor and upon initial compressor engagement, the compressor must pump the oil out causing the ?Bang? noise. Compressor engagements thereafter are normal and less audible as the collected oil has been pumped out.