r-502 walk in freezer troubles

[fridge_kid]

for the past few months at my work we've been having issues with a walk in its charge is 502 and will not come down to temp -10F to -15F the site glass seems to be full at all times we've charged, recovered, charged just when it starts to get down to temp it goes out on high head 350psi all fans working coils clean my boss suggest we've introduced non condensibles which is possible and wants me to pull the charge and replace the it problem is we have little r-502 is there a drop in that requires no oil change?and if any suggestions on how to complete this? thanks

[mikeref]

Welcome Fridge-kid,( head nod and hand shake), to where the depths of knowledge knows no bounds . In this section (refrigerants), you will find extensive reference to all sorts of questions simply by typing R502 in the search bar, upper right hand side. However, the question i have is, why does head presure run up to 350psi towards the end of cooling cycle and not at the start when the heat load is the greatest? Thinking that something else is causing high pressure problems. It's possible you have high pressure to start with and as the day gets warmer, the pressure increases. This could be an aged condenser with poor heat transferre or a fan going out on overload or high superheat.. to name a few. You will need to post more details of this freezer running pressures/temps and gas charge. If R502 is contaminated then there is R408a but i have found it to burn the mineral oil if discharge runs too warm. R507 works well so long as system is in good condition and only run with synthetic oil.. Mike.

[fridge_kid]

i did have an issue with a condensor fan in the early spring i beleive i oiled it and it started working properly maybe not coming up to speed or as you said going out on overload i will check this today as well as try to get some pressures, another on going issue is frost build up on he top of evaporater but i beleive its the high humidity and when they hold the door open for a period of time as the freezer has no curtains ill get back with pressures and temps later thanks

[Gary]

i did have an issue with a condensor fan in the early spring i beleive i oiled it and it started working properly maybe not coming up to speed or as you said going out on overload i will check this today as well as try to get some pressures, another on going issue is frost build up on he top of evaporater but i beleive its the high humidity and when they hold the door open for a period of time as the freezer has no curtains ill get back with pressures and temps later thanks

Oiling a motor to get it running is a very temporary fix. The motor cannot be trusted and it will sieze up again. Always replace a siezed motor.

[fridge_kid]

alright ill get the numbers and replace asap thanks as for the consistent frost build up i finally got the kitchen manager to ok the purchase of air curtains for both the walk-in freezer and walk-in cooler so this should be good as they tend to leave doors open longer than hey should

the unit has a decent sized liquid receiver this makes me ask the question of why its acting like its critical charge?

thanks guys every bit of info is much appreciated

[ccarlos196]

Welcome Fridge-kid,( head nod and hand shake), to where the depths of knowledge knows no bounds . In this section (refrigerants), you will find extensive reference to all sorts of questions simply by typing R502 in the search bar, upper right hand side.
___________________
Floatation Tank

[M.Amer]

check if t.x.v is doing job well,partially blocked mesh filter in t.x.v or orifice (if there is any) can cause frost on small area i think you have problem with t.x.v