Orifice tube? this is not a chevy or ford? Sorry this system does not have an orifice tube that I know of it has an expansion valve in it's place. what is the problem? I'll help ya troubleshoot the A/C issue.
here is the system loop if you're intrested; from Compressor high side it go's to condenser, from condenser it go's passed the drier, from drier it go's to expansion valve, from expansion valve it go's to evaporator, from evaporator it go's back to expansion valve, from expansion valve it comes back to compressor low side to complete the loop.