i have a problem 404-a reach in freezer

[357]

worked on a reach in freezer today. suction was 15 and head was 265. my suction line temp was 58 and my liguid line temp was 107 i had no subcooling and way high super heat. ambient was 97. the box is cooling down to 7 above when i wraped it up and seemed to be dropping. box is normaly kept at -5. am i missing something. i am some what new to refrigeration and would like to get past this hurdle with the wright answers. any help would be appreciated, thanks in advance. if i had to guess it would be mixed refrigerant or the like.

[rocket]

your superheat is way too high
you need to find where you are picking up heat
it's definitely something in your suction line
i.e insulation bad, drier problem, etc.)

[icemeister]

Is this a cap tube feed or TXV? Does it have a CPR valve?

[357]

suction line is insulated back to comp, it is a txv, and it does have a cpr.

[rayr]

What flavor refrigerant??? Educated guess with those pressure would be 502,408,404???? And like the Ice Master asked, what is the metering device?????

[icemeister]

With a 265# head and 107ºF liquid with no subcooling you must be looking at R404A. Since it's a TXV feed, no subcooling would lead me to expect flash gas at the inlet of the valve due to low charge. If it were a restriction like plugged inlet screen or filter-drier, you'd likely see a little, if not a lot, of subcooling. Add a few ounces of refrigerant and see if conditions improve significantly.

[icehouse]

Make sure you do not have a ZP charge expansion valve with a CPR valve.

[357]

i posted the wrong refer origialy i said 404a i meant 409a. working way to many hours lately. it is 409a with a txv. i went back today pumped it down and pulled the inlet screen, it was clean. i pulled the power head and it is good. i pulled the txv apart to inspect the spring and all good there. how ever i did notice some brown crud in the txv. i evacuated and released the charge and ran unit. my pressures on start up were 225/30 the box started to cool down to 44 and then my suction dove down to aprox 12-15 and then short cycled on the low pressure switch. then i jumped out the switch and ran it. pressure dropped to aprox 5 and box temp rose to 49-50. then low side jumped up to aprox 20-25psig and seemed ok untill it did it again and again????? mixed refer?? non condensibles?? or what? helppppp. oh also there is a filter drier with a sight glass after the filter drier and flow throgh the dryer seems fine.

[357]

icehouse im not sure what a zp charge is. cpr meaning crank case pressure reg, wright. that i do not have. but out of curiosity what would be the effect?

[shogun8]

Ice formation in expansion valve? anyone

[357]

2-of the lines on the distributor after the txv are frosting up.

[madjack]

Sounds to me like it's pumping down.Like could be ice in txv also how did you test power head?A restriction in a line might let some refrgerent thru when unit is off but not let enough through when it's running.Real high superheat with only 2 lines frosty-wait is there a strainer before distrubuter?Also did this unit run fine before the call-I mean history is real importaint.But if sight glass is ffull and it's pumping down so we know it's after that so must be at txv or distrubuter.I work way too many hours also but I never give up and only had 1 unit I never figured out.It was a mismatched evap to the condensing sled and the guy before me tried a bunch or txv sizes and distrubuters.One thing I found when I had that system full but was pumping down was a sil-phos plug from whoever soldered lines on distrubuters-they had tried a bunch of different sizes of those also-and the bullets inside of them too.So history is real importaint.I have taken a txv bulb off and held it in my hand to get it to open up before.I have cracked lines at different points and bled some gas thru to assure flow also.You check screen on txv?I think it fits into liquid inlet.I would like to know what you find.Good luck.You might try adjusting txv all the way open-counting turns of course.


[Edited by madjack on 06-26-2005 at 11:10 PM]

[cracker]

How Many Distrub. Tubes You Have?
If You Have Four.....More Likely A Block..... Check The Other Two.