Precision lpu150 frezzer won't freeze

[fenair]

Hi All

Precision lpu150 freezer, Shop owner bought it second hand,

got it home and would not pull down, asked me to have a look,

I degassed, vac'd and pressure tested with n2, charged with 100gr R134a.

Pulls down to zero reasonably efficient, then steady progress from there.
Only ever managed to pull -19 once, this apparently took until the next day.

Once door has been opened a few times, it can't manage much around -10, and if left begins to warm up.

So i have had it over the week end, and triple vac'd it pressure tested for two hours and not a tad of movement on the gauge.

Re-gassed and same thing, it gets to zero OK, then struggles much past zero, puts up a alarm.

Gauge readings are +37 deg HP and -25 deg C LP.

Condenser is warm, pot is hot, and suction at outlet is cold, and ambient at the pot.

The evaporation is via the shelving consisting of three sections, lead in capillary is the top one this is frosted, the other two are not, but cold not iced though.

People i am thinking compressor is not circulating enough, but then why does it pull down up to freezing point, if the capillary was blocked then surely it would have no cooling effect?

Drier is warm, so i assume its not saturated, HP reading taken from the stub off the drier, and i have put a service T in the suction line back to the comp so i could vac either side of the compressor.

What have i missed??

Any thoughts would be appreciated..

Don't want to suggest a new comp and its something less expensive...

Regards and thanks in advance

Pat

Regards

Pat

[lowtempman]

Perhaps insulation is shot and excessive heat leakage into freezer. Your readings indicate compressor is pulling down but bottoms out at some point. A check would be to get an amp reading on the compressor and check what it should be per ratings. If it checks fairly closely then you know the compressor is doing what it is supposed to be doing capacity-wise.




Hi All

Precision lpu150 freezer, Shop owner bought it second hand,

got it home and would not pull down, asked me to have a look,

I degassed, vac'd and pressure tested with n2, charged with 100gr R134a.

Pulls down to zero reasonably efficient, then steady progress from there.
Only ever managed to pull -19 once, this apparently took until the next day.

Once door has been opened a few times, it can't manage much around -10, and if left begins to warm up.

So i have had it over the week end, and triple vac'd it pressure tested for two hours and not a tad of movement on the gauge.

Re-gassed and same thing, it gets to zero OK, then struggles much past zero, puts up a alarm.

Gauge readings are +37 deg HP and -25 deg C LP.

Condenser is warm, pot is hot, and suction at outlet is cold, and ambient at the pot.

The evaporation is via the shelving consisting of three sections, lead in capillary is the top one this is frosted, the other two are not, but cold not iced though.

People i am thinking compressor is not circulating enough, but then why does it pull down up to freezing point, if the capillary was blocked then surely it would have no cooling effect?

Drier is warm, so i assume its not saturated, HP reading taken from the stub off the drier, and i have put a service T in the suction line back to the comp so i could vac either side of the compressor.

What have i missed??

Any thoughts would be appreciated..

Don't want to suggest a new comp and its something less expensive...

Regards and thanks in advance

Pat

Regards

Pat

[vilaman]

Pat,
What is your ambient temp? the HP temp seems a bit low. Also are you getting any cooling of the suction line back to the compressor?
It looks like it is either a little bit short of gas or there could be a partial blockage in the system.
When you charge the system did you weigh in from a vacuum? If so add a little bit more refrigerant to account for the vacuum whilst keeping an eye on your current draw.

Regards
Adrian