Partially frozen evap, (Thick ice bottom-1/3)

[HVAC LLC]

What are some causes for a partially frozen evaporator (besides low charge) on a walk-in evap, 3 fan Larkin food cooler, full charge 404, was running fine, thermostat set on 38, 5 degree differential.
Got a call on this, haven't been there yet. Customer defrosted, but may call me back.
I know that's not much information, but it's pretty much all I have.
I have done all commercial HVAC, not allot of refrigeration, maybe 20%.
Thanks.

[mikep]

TXV probably needs to be adjusted, but if you have never done comm refrig you are in for a fun day of tweeking.

[HVAC LLC]

Probably not so much fun, but thanks for responding.
I will drop by the store and check on it.

[icemeister]

Uneven icing of the evaporator coil like that can be due to an improper distributor nozzle. An oversized nozzle can lead to uneven distribution...essentially overfeed some circuits and underfeeding others.

More than likely though, your ice buildup is a result of incomplete defrosting.

I'm assuming this sytem has no defrost timeclock and relies strictly on the off-cycle time to clear away frost buildup. If ALL of the frost is not cleared off, it will re-freeze and become hard ice.

Add a defrost timeclock and set it up for three 30-40 minute defrosts per day.

[jtrefrig]

if its ice not frost make sure your drain is clear. jbb

[crackertech]

X2 check the defrost and the drain line first.

[270wsm]

Since this is on the same subject, i have a similar question. What causes the Txv and distributer tubes to freeze to a ball of ice without the coil freezing up? I run into this alot on walk-in freezers.

[warm beer]

You're really going to need to know the pressures.High pressure the condenser is dirty or the TXV strainer is dirty,Or you're probably low on refrigerant,Or a evap fan is not working,and of course they might of left the door open all weekend or bad seals.......

[Phase Loss]

Since this is on the same subject, i have a similar question. What causes the Txv and distributer tubes to freeze to a ball of ice without the coil freezing up? I run into this alot on walk-in freezers.

This could happen with a starved TEV. the Liquid is literally flashing to a vapor inside of the TEV.

Or it could be normal and the frost/ice dose not melt in defrost because usually the TEV/distributer tubes are in an enclosed section of the evaporator coil that dose not have heating elements. where as the actual evaporator is in direct contact with the heating elements.

[sarpanch2001]

if its ice not frost make sure your drain is clear. jbb

jtt x2

[itsamine]

Since this is on the same subject, i have a similar question. What causes the Txv and distributer tubes to freeze to a ball of ice without the coil freezing up? I run into this alot on walk-in freezers.

Moisture in the system.

[MPHPS]

I started working at a restaurant performing services and the owner asked me to look at their Larkin walk in cooler that was only at 50 degrees. Found large section of inside and outside of coils in walk in frozen up, removed all ice, rooftop unit very low on freon, recharged got temp down to 38 degrees, 3 days later all still ok and coils still clear, 1 week later top section inside and outside frozen up, charge ok but temp down to 50 degrees, is this not defrosting and where could I locate the defroster I cannot find it anywhere. Model # is 2 blade low profile

[crackertech]

I started working at a restaurant performing services and the owner asked me to look at their Larkin walk in cooler that was only at 50 degrees. Found large section of inside and outside of coils in walk in frozen up, removed all ice, rooftop unit very low on freon, recharged got temp down to 38 degrees, 3 days later all still ok and coils still clear, 1 week later top section inside and outside frozen up, charge ok but temp down to 50 degrees, is this not defrosting and where could I locate the defroster I cannot find it anywhere. Model # is 2 blade low profile

Humm.....................I just don't know were to start with this one.