Trying to save chest freezer

[rancherman]

As some of you know, finding a deep freezer of any shape or size since March is pretty tough.
So of course, I have one that needs replaced or fixed!
This is a Woods CF22.
Last fall, I got a high temp warning buzzer in the middle of the night. No big deal, we just transferred the remaining contents into another freezer.
Opened up the lid and let it finish thawing, and cleaned/dried it up.
symptoms were; Compressor extremely hot. But not making any abnormal noises.. Just minimal refrigeration.
...........something to work on over the winter I figured..............
Well, Didn't happen, and as more and more chickens get butchered here, will be needing freezer space soon. (that's when I discovered new freezers are non obtainium)
So, I put a piercing valve on the suction side of the compressor and attached my gauge. It draws down to about 8-10 inches vacuum. So I burped a little 134a into the line, My guess is about 1/3 of a can.. until I have about 2-3 lbs pressure on the suction side.
Refrigeration appears to be back to normal. Compressor only gets 'warm', not hot.
After 1 week, Suction pressure seems to be 'holding'.. so I'm thinking it's a very tiny leak.. may take several months, or years to lose that 2-3 ounces again.

Then, I noticed the frost on the suction line. about 1.5 inch worth of frost. The compressor hasn't shut down!! It's about 20 below zero in the box! This is with the zero to seven knob set on '4' (should be around 0 degrees) Funny thing, I can turn the knob down to '1', before it clicks off... but after a couple minutes I can turn the knob clear up to '7' before it clicks on.
There shouldn't be such a wide sweep between on or off should there??

Does the 'fine adjustment' screw do anything with how wide a gap there is to the on-off sweep? or is it mainly to dial-in the thermostat to what the knob is set at?

If my leak is a yearly or longer I may just recharge when needed.
But if it's a monthly thing, is there any 'stop leak' products that wont plug the capillary? Rectorseal shows a half ounce product just for home appliances... which I'm assuming most appliances use the cap as the 'throttle' instead of an expansion valve.
Thoughts on this?

 

[panthera]

No expert but - for what it's worth

You can get plug in thermostats for deep freezes from amazon/ebay for less than $40.00.

You just put the sensor into the chest, either short circuit the defective thermostat or set it to coldest if that still works, and plug the freezer into the new thermostat, it into the wall. Dial up the temp you need.

That's easier and faster then trying to get the part which is, as you noted, next to impossible to get.

 

As to the rest, you can have multiple problems at once. I rescued a 1947 GE Refrigerator the same way when nobody could be found who would work on it and that worked perfectly two years later despite the horrors of those tap valves for the real professionals.

 

You'll get advice here over time, sometimes you just have to be patient. Lots of really good refrigeration people here.

 

[goatfarmer]

Is 134A the proper refrigerant?

 

[rancherman]

Yes. big ol' 134a sticker right on the compressor!

 

[combo52]

Leaking Sealed System

Is now badly overcharged, Never attempt to charge or adjust the charge of a home refrigerator or freezer using gauges.

 

These appliances are designed to only be charged using a scale to measure the weight of refrigerant going into the system. Usually by the time it has leaked down to the point that it is not cooling properly you have lost more than 1/2 to 3/4 of the approximately 5 once average charge modern refs like this use. When we find a low charge situation like this we measure in between 1/2 to 3/4 of the specified charge on the tag and then see how long it lasts and look for leaks if you want to try fixing.

 

On chest freezers 95% of the tubing is inside the walls of the freezer so finding a leak and fixing it is unlikely, if you find the leak is in the condenser [ high side ] you can hang an external condenser on the back IF the freezer is in a dry environment otherwise without the outer shell condenser the freezer may sweat badly and rust and mold on the outside of the cabinet.

 

It sounds like your thermostat is working normally.

 

John L.

 

[turbokinetic]

Frosted suction line....

The suction line frosted at the compressor is a sign it's badly overcharged. This will keep the evaporator from reaching the proper temperature to turn the thermostat off. The reason it will affect the cabinet cooling is because the compressor is "wasting" its power trying to cool parts of the system which are not intended to be cold. That raises the pressure in the suction side of the system, thereby raising the boiling temperature of the refrigerant in the evaporator.

The reason this makes the cabinet seem to run colder than normal is due to the thermostat "almost" but "not quite" reaching its cutoff temperature. Therefore there is no "off" cycle.

As John said, the only way to know "for sure" that the charge is correct is to charge by weight. As an interim fix, you can remove some refrigerant little by little until the suction line at the compressor is ambient temperature or warmer. That will make it work correctly under the current operating conditions - but there is no guarantee it will be correct for the entire operating range of ambient temperatures for which the manufacturer designed it.

I'm not familiar with the construction details of these newer systems so this is conjecture.... but with earlier systems they often used epoxied connections between aluminum and copper which could be suspect.

I've had systems which were low and I couldn't find a leak and then they have been running for 2 years plus with no signs of charge loss since that. I just call it a "multi-decade leak" and call it fixed. Hopefully this is how yours ends up.

 

[rancherman]

ok ok!! I'll start all over from scratch. and round up a scale to do it correctly.
I followed a youtube example of going by the suction side pressure for recharging purposes.

 

[turbokinetic]

All of us just want to see you succeed!

There is a lot of garbage on YouTube that is for sure. More good stuff than garbage - but still a lot of garbage none the less.

There are so many different refrigerant metering system designed out there. It's hard to say anything is "always right" or "always wrong," since the designs vary so much.

Thankfully, you gave us enough information about what sort of system you have to work on that it allows us narrow it down somewhat. With a basic cap tube system like this, charging by pressure alone won't be very good idea.

 

[rancherman]

I 'bled off' just a sort burst.. which was gas, not liquid. (just for giggles)
...waiting on a scale to arrive... we needed one to accurately measure other things too...

I found that before I bled it off, my 'chilled' running pressure was closer to 4-5 psi.. 'chilled' meaning the compartment was 10 below zero.(f) Way colder than the '1' setting the knob was set at. IIRC, '4'(midway) was supposed to be around Zero (f). '1' should be about 10 above, and '7' should be 10-15 below zero. +/- of course.

So now, after bleeding it off, and running for several hours, my 'frost' issue is basically a cool wet line. I'm thinking that must be closer to 'normal', as 'running' suction line is about 1 psi.
Filling this thing sure isn't like horseshoes! 'close isn't going to work'.. gotta have a SCALE...LOL. It was just a short burst I bled off..
As far as the temp control, it's still doing it's weirdness.. won't shut off even at the lowest (warmest) setting. Further turning counterclockwise to 'zero' simply shuts it off.. as designed.
.......But after waiting 10 minutes, (to allow Freon to equalize) I have to turn it all the way up to 7 again for the stat to kick the compressor 'on'. (which seems normal considering the cabinet temp of 10 below zero) Seems my 'high end on' part is ok.. it's the 'low end off' is bonkers.
There are some reasonable priced digital replacement stats for European/Australian markets.. but their voltage is different than ours.. rats.
So looking at one for a Danby freezer, with similar mounting ~30 bucks.. Doesn't have the extra terminals to run the warning buzzer.. just simple on-off circuit to run the relay. I may just get an external digital thermometer w/warning to stand sentry.

 

[rancherman]

That sweet temp controller I mentioned... IS Available for US market.. 120v!!

For 16 bucks, some wiring, and making a filler plate to put in where the old stat resided... Should get me what I need!
It's programmable, for delay restarts.. alarm.. all-in-one!

 

[turbokinetic]

Glad there was improvement with the small charge adjustment!

That temp controller should do nicely, as well. An all-in-one solution makes it easier to integrate into the machine.