This is a common problrm of Robinair 34700Z / 347002k & 347112k series machine.so don't worry just do the following :- 1# Verify the ISV tank is not overfilled.if full,remove refrigerant manually from tank. 2# Verify if there is high pressure in the tank.Purge excess air from the tank manually.( Open air purge hose from the tank,then press tank valve as needed) 3#Check the high pressure switch for proper operation,if not then replace high pressure switch.Hope this will solve your problem