zanotti gm3 evaporator icing

[rac.eire]

had a service call on a zanotti uniblock gm3 model,its evaporator has iced up twice already,drain is clear,drain heater element ok defrosting for 15 mins (hot gas) defrost termination temp at 30 deg so its getting the full 15 mins,the controller is new and working ok but a heavey frost is coming on the fins of the evap after a couple mins run time,reduced suction pressure from 1.4 bar to 0.7 by removing gas and still frosting on evap, anybody else come across this?

Zanotti gm3 condensing unit uniblock
set temp -20
eliwell id974lx controller
r404a
capillary fed evap

[cadwaladr]

Check the airflow,,evaporator could be blocked with dirt,or you have load that's too heavy for it.

[larryfogg@gmail]

I have an indesit fridge freezer fridge 10 degrees too warm and freezer-20 good any ideas please

[rac.eire]

thanks cadwaladr, evap is spotless no blockages fan running good,there isint a huge load on the room,i removed some refrigerant havent heard back yet so fingers crossed

[cadwaladr]

normally a good unit as long as the defrost set up match,s the conditions got one on a 20 foot x 8x8 works well at -22c,but the customer puts it thru a manual defrost if he goes in for more than 10 minutes,in that he puts it on defrost just before entering,yes he is one of the customers who thinks !

[Andy AC]

Check the evap fan is running full speed, should be a high speed capacitor motor on these. If the cap is duff, will run at lower speed. Cap can be changed in situ, but is a pain. changing the motor complete is easier.

[rac.eire]

thanks for the replys problem seemed to be down to excessive charge, suction pressure at 0.7bar working perfect