Iced evaporator

[Pedroconsuegra]

Last week I installed new condensing unit with new evaporator coil and new txv. after installation unit was doing properly cycle and reaching temperature. Monday almost 4 days later customer call me that evaporator was full of ice, today I manual defrosted and adjusted temp control was set 30 dg, I undertand that could be several reasons, this unit has pressure control switch, reciever,solenoid valve and thermostat. when temp room reach setting, unit close solenoid valve and then open pressure switch and unit turns off, I observed few cycles and seems to me that is doing what is supposed to do. what could be the reason was completed iced up up to some side od the suction line but no to the compressor in short a period time

[Tesla]

Hi Pedro and welcome to the forum.
Start with checking airflow is sufficient, then gas charge and pressures and control of. Restrictions in pipework can be found checking temp drops - blocked drier, metering device, crimped pipe etc. Is the unit big enough?

[Pedroconsuegra]

Thank you Telsa, Unit is enough because same system I had installed in the same size area in another location with any problem, what I noticed is bubbles in the sight glass but unit had a receiver I understand that when is low in refrigerant unit will run continuosly and evaporator coil will be partially iced and this is not the case, evaporatr is completed iced up up to the suction pipe leading to the compressor but way before reach the compressor shut off pressure valve? if the unit reach temp unit will shut off and will turn on until pressure rise based on the rising of the room temp. this blocked drier will cause bulbus in the sight glass?

[Tesla]

Blocked drier - if I noticed/measured a temp diff between in and out of I would suspect it to be partially blocked and change it. If changing the drier I would also take out the TEV and check to see if strainer is clean. Also a quick check of press & temp of refrigerant in receiver to check for non condensables.

[Pedroconsuegra]

Telsa; Ok, I will do that and I will get back to you. thanks

[Magoo]

The control at 30 degrees will create problems without a partial electric defrost, or at least an off cycle air defrost which would mean a space temp increase above 30 degrees for an extended period.

[cadwaladr]

what sort/type of controller are you using,what are the defrost intervals/defrost stop temperatures could be something simple like drain blocked evap not clearing before restart of cooling ,fan delay,fan start temperature

[Sandro Baptista]

Last week I installed new condensing unit with new evaporator coil and new txv. after installation unit was doing properly cycle and reaching temperature. Monday almost 4 days later customer call me that evaporator was full of ice, today I manual defrosted and adjusted temp control was set 30 dg, I undertand that could be several reasons, this unit has pressure control switch, reciever,solenoid valve and thermostat. when temp room reach setting, unit close solenoid valve and then open pressure switch and unit turns off, I observed few cycles and seems to me that is doing what is supposed to do. what could be the reason was completed iced up up to some side od the suction line but no to the compressor in short a period time

Pedro,

Check the defrost electric coils of the evaporator...some of them can be damaged.

Is it a negative cold store? Check the electric heating of the drain pipe inside the cold store to see if is damage...if it is damage probably the water drain is freeze and the drip tray is full of ice.

[Royal241]

check your superheat, make sure bulb is properly attached and insulated, close expansion valve a few turns,

[Royal241]

don't bother looking for restrictions, you just have too much refrigerant flow (opposite from restriction)

[Tesla]

There are many good points mensioned to look at but I think we are guessing with out more data.
Pedro could you please give us some operating parameters like temps, pressures, superheat, subcooling etc. Could even just be a door left open. A photo perhaps of the ice build up can be very helpful too.