milk truck charging

[garthr]

i have an old milk truck with an icecream freezer. its old and an r12 system. im going to recharge after evaucuting with an r12 replacement, r414a. the plate on the housing states charge with 12 lbs. what reading should i be seeing on the manifold gauges? im feeding it in thru the manifold gauges on a scale thru the suction side. thanks for the suggestions. the system uses cold plate evaporators.

[monkey spanners]

Is it a TXV or cap tube system? I am not familiar with R414a, i would probably start by dumping 10lbs in and then running the system and adjusting the charge until i was happy.
Many replacement refrigerants for R12 perform poorly in freezer applications.

[garthr]

i believe its a cap tube system. i put about 7 lbs in then the scale i used took a dump. not wanting to overcharge or waste refrigerant, ill wait till i get a useable scale to put more in. in the about 2 hrs since charging it, the temp dropped from 31.8f to 9.7f. i didnt think that was 2 bad. thanks for your help.

[garthr]

been holding around -5 deg F since the last post. the compressor is much quieter also. i had put in about 2 more pounds with a new scale.