Problem with Copeland walk-in freezer

[nik0]

Hi, i have a Copeland -18 walk-in freezer on R404A which is not working for long time, it had a leak on high side and for many years nobody repair it, they just kept top it up with gas. I recently start working over it and found the leak and repair it. The problem is there is no sign for the amount gas to be charged so i charge on pressure. I make it suction on 20 psi and discharge is on 240 psi, but its not going down holding 6C in the room. Everything looks fine,but not going down and im confused.

[Tayters]

Thought discharge would be higher in these ambients. Is the compressor pumping? Worth trying a pump down test on it perhaps?

Cheers,
Andy.

[The Viking]

Hi Nik0,

Pressures on their own is pretty useless as gauge of charge or wellness of the system.
What you need to be looking at is sub-cooling and super-heat. This together with ambient conditions will tell you if you got enough refrigerant in the system and how well the system is performing.

[mbc]

20 psi for +6c is less it should be around 70 psi ( +6c - 10 D T = -4 c ) for R 404A

do you have sight glass in liquid line ?

[mikeref]

20 psi for +6c is less it should be around 70 psi ( +6c - 10 D T = -4 c ) for R 404A

do you have sight glass in liquid line ?

70 PSI= 483 Kpa = around -1* C. On a warm room, TX will be open for maximum (set) feed until suction temperature falls within the power element's percentage of control.
At +6 room temperature and at 2o PSI, there is a shortage of refrigerant or the TX / orifice is not feeding.