Help on commercial reach in freezer

[Jesus Quijano]

i have a reach in freezer that is not getting to temp im trying for 0 deegres F using 409a retrofitting r12 i ave 1 psig suction and 150 psig head pressure airflow is good through the coil but i can only get it down to 15 degrees and then the suction line starts creeping with ice after a hitting 15 im out of ideas as of right now

[monkey spanners]

Is it just after replacing the R12 with R409A that the problem started?

If its a capiliary system you will need less R409A than R12 because R409A weighs less for the same volume. So it could be overcharged.

[Kp3]

ur saying that freezer on r12 are u sure its wasnt r502 = r408a

[Jesus Quijano]

the system already had 409 in it and it is direct expansion wat i did to it first was recover nitrogen vaccum because the pressures were 350 hi and 15 low and the liquid was not even hot to the touch to be doing 350psig which should be more then 150 degrees F but when i recharged it to where its at now (which means there was a lot of noncondensables in the line) and at 1 psig it should drop the temp to at least 8 degrees..... anything im over looking? somethng weird about 409 i should know???

[nike123]

http://www.sdm.kiev.ua/eng/refregerants/service3.html

[monkey spanners]

Is this a capiliary or TXV system?

I'm wondering if it has a restricted capiliary and a previous tech had overcharged it to bring up the suction pressure.

[Jesus Quijano]

thats was what i thought when i cleaned it out but when i charged it the capilary was clear i tripled checked it and it flows perfectly and now the pressures stay steady but temp will not drop... im starting to think this was a cooler and the condensing unit doesnt have the capacity to bring it down to 0 could that be?

[big h cooling]

sounds like you have a restriction in the pipe work

[Jesus Quijano]

thank you all for your replies but i learned something new today............. do not ever trust extech multimeters temperature sensor they work perfect all the way down to 40 degrees F but any lower and it gives you a reading way off

[Kp3]

ive only seen r12 as a freezer a on chest freezer. i would suggest getting cond unit details and check with ur local wholesaler that unit has the duty to pull it down to -21degrees