R414b , hot shot troubleshooting reach in freezer.

I apologize for the lack of info on this unit. It is a unit that has fresh food section on the left side and the right side is freezer, this is a commercial unit and each section has its own complete cooling system.
I got the call saturday evening and the unit was not cooling properly(about 20F), its a reachin and they warm up quick from people opening doors; as well the condenser was pretty plugged up, so I cleaned the condenser and it slowly pulled down to 11F.
This is a cap. tube system, there is no tag or marker anywhere that I can find, there is a 414b sticker on the freezer side evaporator, but it is a r22 copeland evaporator. This leads me to believe the unit was pulled from something else, My reasoning behind that is that I think R22 is med-high refrigerant not so much for low temp applications. I have not ever worked with hotshot, I even tried to look it up in my old text book but no mention, I know we had it in the shop; but i never used it.
I did not hook up a high side gauge just the low side:
Ambient 80f
air leaving condenser 98f
low side pressure while running 4psig
I forget the sh but it was high around 50f
I shut down the unit to see what my pressure did to see if I could get a accurate temperature for pt, chart and it went up to 30psig which does not make sense with either r414b or r22
I know the evap is starved only 1/4 of it had frost.
I called the customer this morning to get temperature of box, and he said the compressor was not running. I know the compressor was hotter than my pt chart goes up to. 145-150f
Know with the compressor off I should be able to get accurate reading to figure out what kind of refrigerant it has. If it is r414b WILL IT GIVE ME STRANGE PRESSURE READINGS POSSIBLY BECAUSE OF FRACTIONIZATION?
Does anyone have any advice on this I cant really do anything until I can figure out what refrigerant is in it, If the compressor burned up(i will check it either today or tomorrow) should I change it to another refrigerant.
If you need anymore info or questions please let me know. Next time I go in I will bring pen and paper.
Thanks

I asked Google what R414b was. It says 414b is a substitute for R12 in +40 to +50 F evaporators.
Since your looking for temps around - 8 F, i'd say R414B isn't on board.

Hm... R414B is a environmental nasty sh**, i think not allowed to use or repair equipment with R414B without replace refrigerant to allowed version in most country to days.


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R414B work in same pressure range as R12 and R134a but not so small glide, more close match and not using HCFC and smaller glide is R413A (ICECON 49) and similar blend

If compress dry R414B vapour from -18 degree C and 0.113 MPa absolute pressure (dew point for R414B) to 1.13 MPa absolute (bubble point at 40 degree C for R414B) give isentropic heating to 63.8 degree C for R414B

for -18 degree C to +40 degree C at saturate point for R12 give isentropic heating to 49.8 degree C

same for R134a give give C 48.1 degree C

Real equipment give lot more temperature rising on high pressure side depend of isentropic efficiency and cooling of used compressor

I agree R414B seems not suit for low temperature freezer if not want high head temperature on compressor... is more fit for refrigerator using evaporator temperature not lower than -5 degree C or so...

R414B is blend of 0.5 of R22, 0.39 of R124, 0.015 of R600a, 0.095 of R142B all by weight

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possible R414B-sticker is mean to fresh food side and freezer side using R404A or R502 or similar

Check your filter-drier for temperature drop between inlet and exit. If it is above 0.5K, change!

Thank you for all the input! You all mentioned points that I was second guessing myself on.
I advised the customer that r414b was not a practical refrigerant for freezing applications and he agreed so I am going to do a swap.
I have never did a refrigerant change. If I go with a r404, i know it has big pressure differences. Any advice or a better solution, refrigerant alternative?
this is a cap tube system.
Thanks again all, you are so awesome and helpful!

Thanks for your help. I am a pessimist and the world needs us;) we are called troubleshooters.

Oh and yes I did check my filter, it was spot on.

Quote:

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Originally Posted by romanowski72

Thank you for all the input! You all mentioned points that I was second guessing myself on.
I advised the customer that r414b was not a practical refrigerant for freezing applications and he agreed so I am going to do a swap.
I have never did a refrigerant change. If I go with a r404, i know it has big pressure differences. Any advice or a better solution, refrigerant alternative?
this is a cap tube system.
Thanks again all, you are so awesome and helpful!

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If you go with R404a the pressure increase on the low side is 27% and you have to change the mineral oil to synthetic. The capillary will be the wrong size/ length and the condenser + compressor aren't going to like it.

Going from R414B to R404A is a bigger step in pressure change, new capillaries, new compressor etc. than convert from R12 to R22-system... ie. need complete rebuilding system...

If you check pressure and find around R12 range - stick with R413A (can work with mineral oil) and similar compatible refrigerant in R12 and R134a-range pressure and using existing compressor and capillaries, not shift to R404A or R407C and similar with lot higher system pressure.