How do you guys determine what r12 alternative is being used when there is no lables on the system. Got a call from a chinamen restraunt..walk in freezer holding at 25 degrees. Condensing unit only has r12 listed. Condensing unit only has r12 on lable. Im assuming its probably 409a in this thing since its a lower temp evap or am i wrong. Pressures were 15 low side and 150 on high side. High side pressure seems a bit low to me. Sight glass is filled. I couldnt take a good look at the expansion valve because these guys had meat stacked on both sides of the coil. I told them to make sure that stuff was outta there in the morning and i would be back. Evap and condenser are clean. I have a suspicion ive got a expansion valve problem to deal with.