MNOE

So I took my WJ to have it vacuumed down an refilled after opening the lines while changing the head recently. I was told that the compressor is showing a little low pressure and I need to change that plus the drier/expansion valve. What do? Think ill get away with changing the compressor and bringing it back for the recharge? I wasn't cold before I changed the head, just cool. And I know the refridg wasn't low because I had it checked before.