A/C retrofit kit

My 91 Olds Cutlass Ciera had a leak in the evaporator & hasn't been converted to R134 yet. I've had the system evacuated by a local shop & picked up a new evaporator & accumulator, these are easy enough to do, & then I'll take it in to have the recharge done. The A/C retrofit kit to convert to R134 is something I haven't done yet. The new high & low pressure fittings are straight forward, but is it necessary to put in all of the new O-rings? Any info would be appreciated.

New O-rings is recommended that way you don't have to re-do them if old O-rings leaks.

However, if you put new AC components. You must pull the vacuum with a vacuum pump for at least 60 minutes. It allows you to get rid of any moisture in the AC system and allows you to find out if there is any leak. After pulling the vacuum for 60 minutes then you can introduce R-134a refrigerant.

New O-rings is recommended that way you don't have to re-do them if old O-rings leaks.

However, if you put new AC components. You must pull the vacuum with a vacuum pump for at least 60 minutes. It allows you to get rid of any moisture in the AC system and allows you to find out if there is any leak. After pulling the vacuum for 60 minutes then you can introduce R-134a refrigerant.

I will definitely use new O-rings at the evaporator & the accumulator. I wasn't sure if the other connections at the compressor, condensor, etc..., should be distrubed if they were not leaking anyway. Makes sense to do it all now though. Thanks.