Help me with R-22 Walkin coolers

[eddie-boyz1]

Me- install 3 yrs. started green, did 4 yr apprntc. leading jobs after 18 mos light comm under 15tons. then went to learn service. - learned residential service from self experience. learning refrigeration at day job but it's like self taught too! Any way I learn fast but don't have much pro teaching.

These R--22 walkins what is the low pressure generally at?> seems low evrywhere like low 30s- why you want your coil at 8 degrees?? or should it be 40 Why 15 degrees? if youu box temp is 35-40 why is the coil so cold?

I got a walkin at dominoes. r22 condensor on roof. evap on box ceiling is double coil on sides w two fans pulling air in center. got condnsing pressure at 30degrees above ambient. no bubbles sight glass. superheat at cond is like 42. After charging to that -low side still 30 lbs ish. frosted up txv and freezin coil still. try opening and closing txv after defrostin. seems like txv aint frostin now. but lowest superheat at evaporator I can get is like 20degrees..
does fine two days then coil icing again and box temp not holding. txv not icing but distributor and tubes iced reall good and 1 side coil icing hard other a little ( and there are 4 tubes, 2 to each coil) so if txv restricted why are coils acting like they are in series when they are parrallel?? air td on one coil is 10 degrees and it is icing up. other side only icing on one tube in coil and td is only like 4-7. WTF this doesnt add up to me. THen again- I need some teachin!!
Gimme the basics I'm missin here please.
Eddie

[Patronsilver]

What is the original problem?

[pecmsg]

You’ve got the post count so apply for pro membership.

[baub]

Sounds like you have a low velocity coil. This could cause a lower suction pressure. You might have a restriction to the side with the low TD. Check out the distributor and it's position.

Do you have a defrost timer? If so, how is it set?

It sounds like you are on the ball, but please, for us old gruppies, put a little time into spelling and sentence construction. That would make your post much easier to understand, and I bet you would get much more input.

[eddie-boyz1]

Originally, slightly warm box temp and evaporator coil freezing up. Checked and freon was low based on 200 lbs high side at a 85 degree ambient. added 2 lbs to get up to a 30 degree split. cooled better but still freezing up. still to warm at 45 degrees box temp and frreezing. no defrost- low pressure cutoff set at 20 lbs. Low Velocity coils? They use those often on R22 units?? Noone's been in it lately so why would the distrubutor tubes get restricted?? They did appear in normal shape w no kinks. how would these things get restricted instead of whatever getting caught up in the txv.
originally the txv was really frsted over too but I think that was before I added freon, now I can't recall if after, yeah it was that's why I thought it might of been restricted or had moisture froze in it.

p.s. I am used to texting lol

[joemach]

On r-22 coolers you will need at least a defrost timer/clock. Your evap coils should be air defrost and the defrost cycle will prevent the compressor from running.

This seems to be a phenomenon with R-22 coolers. I am not exactly sure why but there are some real smart guys here that may be able to explain it.

I have not seem an R-22 cooler that did not frost up. You need a defrost/off cycle to keep the evap coil clear.

HTH

[Riverguy553]

I have ran into something similar on a WIC without a TC, I added one and the problem was solved. If it's a high traffic box with alot of humidity in the area I would do 6 x 30 or just the normal 4 x 42.

[fool4school]

What is the super heat?? WHat is the compressor?? Is the Evap. cLEAN ?? May need to lower the low press. cut out set point for lower Sat, and prevent condensing in the evap. on a off cycle..

[eddie-boyz1]

If it has worked fine as is for years- then something must have changed within the system Wouldn't that stand to reason? coils spotless- have to check compressor and mentioned high superheat earlier. wouldn't lower my low pressure cut off only cause it to run longer when it is frosting up and cause it to ice over MORE??? I was considering raising it and thinking my txv is not functioning properly---- IS IT functioning properly with these symptoms?? why can't I get less than 20 degrees superheat at the evaporator?? Hello- I thought it did not have a defrost timer cause it was only using the low pressure cut out- let me check and see if I can find a timer I missed.

[aixha1969]

Need these inf.

out temp?

subcooling?

superheat?

low pressure?

high pressure?

delta temp?

please use this format.

[mjm88]

i would get your subcooling.see if you might hav a restricd drier or txv. adding a time clock is only gonna mask the freeze up problem not solve it. if it didn't freeze up before then there is a reason why its freezing.txv, low charge, air flow problems, differential on tstat to close not giving it enough time to defrost in its off cycle. theres more that can cause but those are the first things i always check.

[pdrake65]

Me- install 3 yrs. started green, did 4 yr apprntc. leading jobs after 18 mos light comm under 15tons. then went to learn service. - learned residential service from self experience. learning refrigeration at day job but it's like self taught too! Any way I learn fast but don't have much pro teaching.

These R--22 walkins what is the low pressure generally at?> seems low evrywhere like low 30s- why you want your coil at 8 degrees?? or should it be 40 Why 15 degrees? if youu box temp is 35-40 why is the coil so cold?

I got a walkin at dominoes. r22 condensor on roof. evap on box ceiling is double coil on sides w two fans pulling air in center. got condnsing pressure at 30degrees above ambient. no bubbles sight glass. superheat at cond is like 42. After charging to that -low side still 30 lbs ish. frosted up txv and freezin coil still. try opening and closing txv after defrostin. seems like txv aint frostin now. but lowest superheat at evaporator I can get is like 20degrees..
does fine two days then coil icing again and box temp not holding. txv not icing but distributor and tubes iced reall good and 1 side coil icing hard other a little ( and there are 4 tubes, 2 to each coil) so if txv restricted why are coils acting like they are in series when they are parrallel?? air td on one coil is 10 degrees and it is icing up. other side only icing on one tube in coil and td is only like 4-7. WTF this doesnt add up to me. THen again- I need some teachin!!
Gimme the basics I'm missin here please.
Eddie

A few things: This type of evap catches all the crap inside. are the coils clean inside where the motors are? If you have a clear sight glass did you determine if it was liquid or empty? Just have to question why you put more charge in it. Does this unit have a liquid receiver? Suction accumulator? How is this unit pumping down at satisfaction of t-stat?

[joemach]

i would get your subcooling.see if you might hav a restricd drier or txv. adding a time clock is only gonna mask the freeze up problem not solve it. if it didn't freeze up before then there is a reason why its freezing.txv, low charge, air flow problems, differential on tstat to close not giving it enough time to defrost in its off cycle. theres more that can cause but those are the first things i always check.

My experience tells me that R-22 coolers always tend to frost up. Need an off cycle to keep the coil clear of frost/ice. Of course it assumes all other issues are handled as mentioned above.

1. S/C
2. S/H
3. Clean & clear evap & condenser coils
4. Clear sight glass
5. Fans spinning in correct direction
6. ... etc.