I’m replacing everything in the AC system (compressor, condenser, drier, and hoses) except the evaporator and expansion valve because of their location, I’m HOPING their still good!! My question revolves around flushing the evaporator and exp valve while the hoses are off.
Is the exp valve a one way valve so any junk or old oil would come out the right opening during flushing ? In other words is there a entry only & exit only ( for flush) on evaporator opening’s on the firewall ?
The reason I’m doing all this because the compressors been leaking and 22 year old components. Time to bite the $bullet$ . Thanks everyone.
You should replace the expansion valve, if it’s not functioning correctly, nothing else will work correctly.
Thanks for the reply Al. After reading the R&R of the expansion valve I would do without AC or get rid of the car. Like said , the only thing wrong was the compressor leak and age.
I just took a look at the LOE required to replace the evap core and expansion valve. Just put it under vacuum for a very long time and hope for the best 
Just use compressed air and blow it in BOTH directions at the bulkhead connections to get as much debris (IF ANY) from the valve. Jaguar does not offer the valve as a separate part from the EVAP core (NSS). You can find the valves from aftermarket suppliers but it is BURIED in the climate control housing.
There are solvents to flush the systems so it might work to flush the EVAP core also.
I do this every few years for customer cars when the receiver/drier desiccant bag ruptures. The little beads contaminate the line from the rec/drier to the EXP valve and I blow the beads ‘backwards’ from the line and valve with A/C system flush and compressed air.
Sometimes it requires a few ‘backflushes’ but I get them all out. A recovery machine for 134a is required for this to save the refrigerant, otherwise it gets expensive to drain/fill the system a few times if the system clogs again.
bob