ihave a walk in freezer with a suction of 8psig high side of 200 sight glass is clear. the box temp is only 30f. it need to be -10.r22. i usually just do hvac but our frig guy is on vacation.the suction has no sweat at all. what should my pressure read and if i get a 10 degree sub-cooling would that be ok?
What's your ambient temp? What's your controls look like? Depending on your ambient temps it seems a little low on the suction. Have you checked for a dirty or Iced up evap. If it is not dirty but iced up try checking your defrost circuit. Lots of different reasons for problem. Need more info.
Sounds like the coil is iced up..get out the hose or replace the txv
I want to know the line temp at the suction line just before the compressor.
If your evap is iced over, that would account for both your low back pressure and your high box temp.
However, you did mention your suction line wasnt sweating.
I take this to mean: your suction line isnt very cold.
If you were iced up, the suction line would be frosting. AND ... you would see bubbles in the sight glass on the liquid line.
1) check your airflow totally. Thuroughly!
2) check your evap coil for any physical restrictions, plastic bags, ice ... the whole nine yards.
3) find out what your TXV is doing with your refrigerant.
You need to know what the freon is.
are you sure it's a freezer and not a cooler?
R22 sux as a freezer