the unit model i am working on is a Daikin RP125L7W1. i found the unit short of gas, reclaimed, blew pipes out with nitro because i thought it might have been a blockage then pressure tested and held for 12+hours. after all this left on vac over night and added refrigerant and same problem occured with the suction and discharge both pulling a vac?? how would i locate the 'Check Valve'??