walk in freezer icing after expansion valve

[Bobbycold]

The problem with typing here on the forums is that you don’t get the visual and tonal cues that you get from a normal face to face conversation. I'm not a condescending person at all and I really meant no offence. Perhaps it’s my writing style or the way I expressed what I was trying to say, that gave that impression. I actually came to this web site with the mindset of having a technical rumble in the dirt with my peers. I didn’t come here to offend anyone or to make trouble. And that’s the truth.

Just between us on this board, I think screen names play a part of why sometimes someone gets hostile or such. Often we might bite our tongue when we talk with people who know who we are, but here we are Malcor & Bobbycold. I suspect people know that my name isn't Bobby Cold. Some may know me as Johnny Cold in real life (LOL). If you offend people here, what are we going to do about it. It isn't like we're coming to burn down your village and slaughter your goat. We don't even know who you really are. With such anonymity, it has to be tempting to unload on people.

[timebuilder]

I'm not convinced that screen names are the root cause of friction. I DO think it has to do with the limited nature of written communication, and the lack of writing most guys have done who are under 40 years old, because it became less emphasized in the past 30 or so years in public schools.

There ARE times when I read something, and I have to ask if the poster is even a tech, just based on the way the information is given, and what conclusions are being drawn in the questions asked by a poster. Hopefully, it doesn't seem condescending when I do that, as knowing the experience level often helps one to GIVE help, where that assistance is warranted. Obviously, we don't want this to be a DIY site, but we also have to bear in mind that there is a WIDE range of experience among us. There are guys here that have a lot of great experience, and I come here often, looking for tidbits that make me a better tech, because there is always a chance that someone has looked at something differently than I might, merely by their own life experiences being different than my own. That's what I love about this place.

I'd say we should all put down the long knives and say "apology accepted," and move on.

If the OP has more questions about this issue, we can help.

From the handful of posts I have read, franctionalizing or mixed refrigerants would not be my guess, unless the owner had told me that he or a friend had tried to add gas, or if perhaps I saw a jug sitting out back...

[Bobbycold]

Timebuilder, I agree that that is part of it. Sure we have become a less civil society, yet, I know in my personal experience that I am a little less aggressive if people know it's me posting an attack. On other boards that I discuss politics and rural living, I post with my actual name, and I weigh every word I say. This isn't a topic that inspires my wrath to begin with, so I'm not inclined to start ripping into anyone. If someone is bent on doing something that time has taught me to be bad, I accept that I will not prevent their continued use of a practice I disagree with. That doesn't compell me to get up in anyone's face. If they have a heat pump gage set with a set of six foot hoses, and they are bent on checking a small ice machine with it everyday, ultimately that is between them and their customer. I will share that I use a very short hose with the gage that can withstand the harvest cycle and a valve, but, if they are bent on doing things their own way, that is their business. While I fully understand what is the reasoning behind Navy 06. I use to have to frequently reclaim all the refrigerant from a system, weight it and PT the bottle to verify the blended refrigerant was good, even though I knew the problem was electrical, because the unit felt it was to be done. I learned in the service, as well, though on the outside we get a little more flexiablity. At the point that post appeared, it appeared a possibility, though probably not the next check. I understand where that comes from. Like I already said even though I know many who tweek a little gas into an ice machine or small appliance, I usually still reclaim everything, put a vacuum to it and weigh a charge into the unit. That is what I was taught and it is pretty acurate. Some of those service habits will likely be with him forever, some will probably not. It certainly isn't a stupid idea.

[jpsmith1cm]

You misunderstood what I wrote.

I stated that if R404a were contaminated with R410a or R407c (or any other refrigerant) that it would be highly possible. That is because there would be a lot of uncertainty where blends were mixed, resulting in a new unknown refrigerant type. I never compared R410a to R404a and am not sure why you thought I did either.

Re-re-reading your post, I see that, now.

I wouldn't consider it fractionation, though, but a mixed refrigerant. Fractionation describes a very specific phenomenon and it isn't nearly as common as some people think that it is.

[VTP99]

Personally I have never seen a refrigeration system using R410a. (excluding a/c refrigeration) Also I would not expect any refrigeration tech to think that R410a would be a possibility as a refrigerant in such a system. Now R22 or R407 that could happen and there was a thread on here in which that happened.
Oh....I'm going with low on charge theory

[markettech]

Personally I have never seen a refrigeration system using R410a. (excluding a/c refrigeration) Also I would not expect any refrigeration tech to think that R410a would be a possibility as a refrigerant in such a system. Now R22 or R407 that could happen and there was a thread just on here in which that happened.
Oh....I'm going with low on charge theory

I was at first, too. But, with the OP adding refrigerant and observing a 100 psig increase in head pressure with only a 2 psig increase in suction....at a +20F outside ambient - something funky is going on.

[VTP99]

I was at first, too. But, with the OP adding refrigerant and observing a 100 psig increase in head pressure with only a 2 psig increase in suction....at a +20F outside ambient - something funky is going on.

How about a head pressure control stuck in bypass ? He could add gas till the cows come home and he still would be feeding the TXV with hot gas. Am I reaching for straws yet.

[Fridge Repairer]

Assuming you have a full system charge on sounds like to me you have a bad TXV. another thing you want to check is make sure you have the proper nozzle in your distributor. Check the distributor tubes for proper size. If they are 3/16 inch they are or were for an R-22 system. Your distributor tubes should be 1/4 inch. If your distributor tubes are wrong chances are your nozzle is wrong too.

Goodluck

[IceGuy10]

How about a head pressure control stuck in bypass ? He could add gas till the cows come home and he still would be feeding the TXV with hot gas. Am I reaching for straws yet.

Its either this or contamination.
I'm betting its the headmaster, sure sounds like its stuck wide open to me.

[TopDeadCenter]

How old is this system?

If its been running for a long time you can probably rule out have an issue with your bulb placement or a system design itself.

if the customers knows what the refrigerant is im sure he knows he has a leak and previous techs have just kept adding more because cheap customers never want to pay for the good fix, but techs have to stop offering temporary fixs so we can raise the industry standard and force people to make decisions based on the equipment and not their wallets.

id recommend pulling the charge and pressure test it. start at the begining like a new install. sounds like you have a leak and your loosing your charge. low sub cooling is a sure indication of low charge. if the sight glass was bubbling and your sub cooling was 15-18 id say your evap coil was blocked and probably needed to be cleaned.

the raise in high side pressure could be because your creating a new blend of refrigerant and depending on whats left in the system from previous fractionation your pressures would be all over the place.