Walk-In freezer ice build up

[Royal241]

Bohn evaporator, 2 fans, indoor condenser, 404a, pump down system, FREEZER walk in box. on the left side of evaporator I have a lot of ice build up. it's on the side where the expansion valve is. the ice built all inside and started to develop on the outside, also worked its way to behind the left side fan. defrost system works fine, but the limit is on the other side of the evap and when there is no more ice terminates.
What is the cause of ice building up all around inside the left side (expansion valve)? There are no ***** leaks. But what I observed is that the solenoid valve is not closing all the way (leaking through) and when in defrost the compressor starts every 3 minutes for about 20 sec. I will replace the valve, but can that be causing my icing? I think so, but not sure, since is only on the left side. Thanks for any suggestion, Daniel.

[install monkey]

change solonoid and comfirm the gas charge, as its an itegral system the gas charge should be marked up on the data plate

[Royal241]

it's not low on *****, I was going to pump down, replace solenoid and dryer, vacuum and use the same *****.

[chemi-cool]

If its low on *****, there is a leak, find it first and fix it, afterwards do as you suggested.

[lana]

Another problem could be the defrost elements. Two ends of these elements do not get hot , say 10cm. The problem could be from the build up of ice (not defrosting at each cycle).

[krgari]

I would check the TXV. Make sure it reacts when you warm up the bulb

[monkey spanners]

What they^ all said, plus check for air leaks bring moisture ladden air in if there are and holes in the roof for pipework etc near where the icing problem is.

[Royal241]

i will be on job site today, will post results later on today, thanks for the tips; I will look closer for air leaks, seems to remember some ice build up on the top joint behind the blower.

[sokold]

move the defrost probe to where the ice is, termination temp should be about 15C and duration should be 25 - 30 mins. Initiate a defrost cycle, put a wooly hat on and watch the coil and see how the ice melts.

Check the heater elements with an amprobe, check the drain heater, check the door shuts properly/the staff shut it properly, make sure there's a drip time....2 mins. Is the condensate drain trapped/PRV working properly?

My 2 bobs worth :)

[Royal241]

your 2 bobs worth is what i did today; replaced solenoid valve, and moved the defrost termination to the other end, there was no ice build up in 3 days ( i manually defrosted/melted it away 3 days ago), looks like it will last :)