Hello Guys,,

We have 1700 cubic meter freezer cold store @ -20*C, this freezer have been installed 8 months ago, and it was running perfectly, b4 3 weeks, we've started to problem of not achieving temp. (Possibility of undersized units is not there coz the before 2 months the amb. temp. was 46 and now adays it is 40), when i went there i found too much of ice on the evaporator coils. so i did the following:

1- i have increased the deforst stop temp. to be 25 and have an override from the defrost stop time.

2- i have decreased the time between two defrosts.

3- i increased the drainage time to 10 minutes.

the temp. there now is -12, and it is not bringing the design temp. except night times, i've checked if there is any possible location that the out side humid air will go through but there is not, also the box door is opened to an air conditioned space..there is still ugly frost on the coil,, the coil heaters are running properlly !!

any ideas.

regards..