Why? PLEASE HELP!

[davids2212]

hi
i had a job today with a foster freezer! it had no refridgerant in it but needed r502. i repaired the cabinet and then filled with r408a but the temp went from +22C and fell and sat around -1C for hours!!!! have i got a control problem? HELP please!!

[monkey spanners]

Could be lots of things, over charged as i think you have to weigh in less of R408A compared to R502.
Could be defrost heaters stuck on, etc etc.

Need more info, what temps and pressures, all fans running? air flow? door seals ok? How well did it work before it broke?

[davids2212]

I have only been doing this for three months so any help is much appreciated (passing C+G 2079 doesn’t make you a fridge engineer!!!) Got to play with the freezer for a couple of hours today! From previous engineer documentation back from 1993 they filled the freezer with 450g of r502. I put in 300g of r408a today and the freezer sat a –11deg C. low pressure reading 1.8 bar and frost build up on low pressure (suction) side before compressor (have I still over filled it?). The defrost heaters are not stuck on, good air flow, fans working and new door seals. Ladies in the canteen told me that the freezer always had a problem reaching temp and from when I first got the job there was a lot of ice build up on the evaporator.


Please somebody put me out of this misery, what have I missed!

[Clk320_Greg]

Is it not undersized if its never worked?

[mad fridgie]

I have only been doing this for three months so any help is much appreciated (passing C+G 2079 doesn’t make you a fridge engineer!!!) Got to play with the freezer for a couple of hours today! From previous engineer documentation back from 1993 they filled the freezer with 450g of r502. I put in 300g of r408a today and the freezer sat a –11deg C. low pressure reading 1.8 bar and frost build up on low pressure (suction) side before compressor (have I still over filled it?). The defrost heaters are not stuck on, good air flow, fans working and new door seals. Ladies in the canteen told me that the freezer always had a problem reaching temp and from when I first got the job there was a lot of ice build up on the evaporator.


Please somebody put me out of this misery, what have I missed!

What are they putting into the freezer, is it frozen or are they trying to freeze product. (application)
The temp diff seems OK on the evap side, indicating correct air flow.
Is this a capilary system? if yes then I suspect the capilary is the incorrect size (to short and/or to large in diameter)

[tonyelian]

hi david
as mad fridgie said frozen product is much different from fresh productfreezing
so if u can providde more info u can get more help
size of freezer
size of comp&evaporator
size of cap tube
type of product fresh or frozen

[1torr]

Check s/h if its icing onto comp, or fit sight glass. Perhaps the compressor isnt pumping efficiently, is it in a warm area, is the condenser spotlessly clean?