Anyone want to take a stab at diagnosing this?

[Bruce]

Hello all,

There should be pics attached.

I just came home from a few weeks out of town, and when I opened the door, I heard a loud racket coming from my Vendo 81. It looks like it was the evap fan hitting my froze/frosted up evap coil. I defrosted it, did some general cleaning and fired it back up a few hours ago. Just took a peek, and as I suspected, the frost has returned. I expect it to get worse.

Probably a pinhole leak in the coil? I had that before, soon after I bought it.

If that's what it is, what are my options? I replaced the whole refrigeration deck with a brand new sealed unit in October of 15, is this normal for these pieces of equipment? Am I pretty much screwed and need another one?

Thank you for any insights you might have.

Edited for typo

[johnieG]

well if your evap' coil is fully frosting over & turning to thicker Ice & the fan's hitting it , and you have good air-flow from teh evaporator fan itself, it's probably not low on freon, but you may have excessive air leaking into the machine ( Gaskets cracked/missing dried up & shrunken) or your T-stat may not be cycling the compressor on & off like it should ( the evap defrosts during the compressor "Off" portion of the cycle) again it may be an air leak causing the T-Stat to run the unit all of the time never giving it a change to rest the compressor & defrost the coils,  or if you have Icing all the way down the return/suction line ( larger of the two copper tubes) outside of the bottle compartment & back towards the compressor, you may actually have an over-charged system if you've recently tried to add gas to it to "fix" the problem, But you cant tell from guessing, you need to get a set of gauges on it & check the system charge.

also make sure your T-Stat isn't stuck "On" this can cause Icing over the evaporator coils too. like I said, it needs to shut off once in a while in order to allow the coils to defrost.  typically a machine will have a 60/40% duty cycle ( On vs Off time)

Oh & make sure you have sealing putty behind the silver line cover show in your pictures, or it will act like a chimney & allow hot humid air inside your machine.

But If it's staying iced over just from the where the cap' tube meets the first row of the coils, it may be undercharged, but you need a gauge to tell, otherwise you're just guessing in the dark.

[Bruce]

Thank you for the very detailed response, it might not be as bad as I thought. A few things I looked at.

It is cooling, when I shut it down this afternoon to let things defrost, it was at around 40 degrees. But the frost was building, even more than was in the pics. maybe the top sixth of the coil had frosted.

The seal seems to be ok, it is still supple, and seems to have some give. I'll look closer at the alignment of the door, but don't know how that would have gone out of whack.

I haven't "topped it off" or anything, I put it in about 4 years ago as a sealed unit, and it is still sealed, as far as I know. I would have to add taps to check levels/service it, if I remember correctly.

The T-stat might be the issue, I was able to turn it down and when fully shut off, (or so close that there was hardly any difference from all off)  the compressor did stop. Before I left for work tonight I slooooooowly turned it up until the compressor kicked in. I'll check the cooling/frost situation again this morning when I get home. (I work overnights)

Or, it may be undercharged, as you mentioned. Which I guess means a small leak somewhere.

The only other thing of note is, about a month ago, I was stocking the machine, and I noticed the condenser in the bottom section, by the compressor, had a pretty think coating of dust/cat-hair/something on the outboard side of it. I cleaned it off, and went on my way. And now this happened. I'm thinking it's unrelated, but thought I'd mention it, in case there is an angle I'm not thinking of.

I'll update this in the morning when I can put eyes on it, and then ask what the next best step is, once I know what it is doing since I turned the T-stat to it's lowest (not low temp) setting. Troubleshooting the t-stat if that is where the symptoms point, or the charge.

Thank you again.

Edited for grammar.

[Bruce]

Ok, when I got home, I noticed the compressor wasn't running (Yea! I think, lol) and it wasn't frosted at all, but it was cold. Not real cold, but yesterday before I left for work I only turned the T-stat till the compressor kicked on.

So, I scooched it up a bit more, till the compressor kicked back on, (15 minutes in I took a peek, and there is a very light frost on the same pipes) and I will check again in about 6 hours.

If it will shut off and go thru a defrost cycle, maybe it was just a stuck T-stat? If so, it may stick again, so I will have to monitor it. (that is, if it does go thru the proper cycles)

[Bruce]

Well, after that little hiccup, it seems to be doing ok.

Consider this thread resolved, at least at the moment. (fingers crossed)

Thank you again.

[MoonDawg]

      You can get a refrigeration thermometer at any hardware store for under 5 bucks. Set it in the window so you can read the temperature every time you walk by the machine.
If you notice it running below 32 degree's again, open the door and smack the thermostat with the handle of a screwdriver and it will shut off. Do the same thing if it gets too warm.
Doing this a few times usually corrects the problem but it wouldn't hurt to order a new T/S to keep on hand, you just may be needing it in the future.

[cohammer]

Yep it is always best to keep thermometer inside, I just put one in an empty bottle section so I can look thru door at it