Walkin freezer puzzle

[Matthonda98]

Got this walkin freezer that has a heatcraft model - PTN031L6B all in one unit mounted ontop of a 6x10 walk in freezer

70F outside walkin freezer
8F inside walkin freezer
28.5f wet bulb inside
58 wet bulb outside
txv
265 psi high side
84f high side line temp by txv 116F before condenser
42 psi low side
17F low side temp
evaporator temp -10

18 SC
22 SH

the set point is -10F but the freezer will not go below 8 F

evaporator and condenser are cleaned.

28oz of 404a

any ideas ?

[Restaurant Mech]

How clean is the condenser coil? 14 above ambient liquid line seems like it's not able to reject enough heat.
Or... I've had fan blades mounted backwards for years

[Matthonda98]

its clean but i can blow them out again. airflow is coming from outside through condenser (so sucking air into condenser)

[Matthonda98]

also suction line is frosted but i know the system has full charge. my confusion is the pressures are way off from name plate.

says the unit should be running 450 psi high 178 psi low

[VTP99]

Superheat way to high for a freezer should be 4-6°f
Where did you get that measurement ?

[Matthonda98]

my compressor has low side port right on he compressor and i grabbed temp right before compressor on suction line. unit is txv so i wasnt as concern about superheat. but im leaning maybe a bad Txv
thoughts?

[VTP99]

You need to get a line temperature at the txv bulb location.

[rundawg]

I'm doing some house cleaning here..................

I moved this thread out of the "AOP Commercial forum" because it is getting into more technical information then should be provided in that forum.

OP - your profile states you are an "equipment owner," but this thread sounds like you are the tech on scene. Please update your profile.

Take note of this new location of your thread as the "Moved" icon in the other forum will only last a day.

[Snapperhead]

my confusion is the pressures are way off from name plate.

says the unit should be running 450 psi high 178 psi low

So uhh ..... how long have you been doing Refrigeration ? (you sound like a Residential guy trying to repair Commercial Ref)

Those numbers are used for Testing , they are not meant for a Running unit

[Snapperhead]

its clean but i can blow them out again. airflow is coming from outside through condenser (so sucking air into condenser)

So the unit is Recycling the hot air ?

[Snapperhead]

txv
265 psi high side
84f high side line temp by txv 116F before condenser
42 psi low side
17F low side temp
evaporator temp -10

18 SC
22 SH

the set point is -10F but the freezer will not go below 8

Have you dumped more 404 into this - attempting to raise suction ? Your numbers aren't matching up

[ammoniadog]

From your comments about the frosted suction line, the test pressures that it says on the nameplate, and the fact that you seem to be more concerned with subcooling than superheat (on what I'm assuming is a unit that has a receiver), I can tell that you don't have much experience with refrigeration.

Does this thing have a receiver? If so, 18°F subcooling seems pretty high. Could this thing be overcharged, or are you sure that it still has the factory charge amount? On receiver systems, subcooling should NOT raise while you are adding refrigerant. If it does, that means that it's way overcharged and that the receiver is completely full. If this system doesn't have a receiver, then disregard what I just said, although 18° of subcooling would still be high even for a non-receiver system.

A plugged up filter drier might also be able to increase subcooling. Try taking a temperature measurement before and after the filter drier to see if it's the same on both sides.

Your head pressure also seems high for the 70° air that you say is around it. Are you sure it's 70° up there? Usually these things get installed in a confined space with poor airflow which causes the condensers to recycle the air over and over again, which causes the temperature to become much higher than that.

If those things actually check out, my next guess would be air infiltration. Is this thing sitting on the box correctly, with no big gaps where non-conditioned air could be getting into the box or the evaporator section? Is the door gasket in good shape and is the door closing correctly?

One last thing to check is the heated relief port thingy that's usually installed above the door. Make sure it's heater is working and that it's not a giant ball of ice inside of it. These things sometimes go bad and that basically creates a big hole where unconditioned air and humidity can infiltrate the box 24/7.

Keep at it, and get back to us with more questions and let us know if you figure it out.

[Red850kid]

my compressor has low side port right on he compressor and i grabbed temp right before compressor on suction line. unit is txv so i wasnt as concern about superheat. but im leaning maybe a bad Txv
thoughts?

42 psi is a 9 degree evaporator, which will not produce a -10f box.

At a -10 box I would expect to see the suction around 17-20 psi.

You say the evap is -10f?? How so with that suction pressure?

[pecmsg]

Got this walkin freezer that has a heatcraft model - PTN031L6B all in one unit mounted ontop of a 6x10 walk in freezer

70F outside walkin freezer
8F inside walkin freezer
28.5f wet bulb inside
58 wet bulb outside
txv
265 psi high side
84f high side line temp by txv 116F before condenser
42 psi low side
17F low side temp
evaporator temp -10

18 SC
22 SH

the set point is -10F but the freezer will not go below 8 F

evaporator and condenser are cleaned.

28oz of 404a

any ideas ?

116°F on the discharge line? 70° outside air and 84° liquid line at the x-valve? Where are you picking up heat?

22° SH at the compressor? Danger Will Robenson Danger!

[Red850kid]

A bad txv?

Close the expansion valve a quarter turn when the box is hung up at 8f.

Does the suction psi drop? Does the box start pulling down more?

Heaters are not running correct? Measure SH at coil. What is it?

[Red850kid]

116°F on the discharge line? 70° outside air and 84° liquid line at the x-valve? Where are you picking up heat?

22° SH at the compressor? Danger Will Robenson Danger!

Good point. Once again, I have overlooked the big picture.

If I understand correctly, the condensing unit is in located indoors.

What is the temp of the air entering the condenser? Leaving?

[VTP99]

OP ghosted their last thread 🙄
Might happen again ....

[Red850kid]

Got this walkin freezer that has a heatcraft model - PTN031L6B all in one unit mounted ontop of a 6x10 walk in freezer

70F outside walkin freezer
8F inside walkin freezer
28.5f wet bulb inside
58 wet bulb outside
txv
265 psi high side
84f high side line temp by txv 116F before condenser
42 psi low side
17F low side temp
evaporator temp -10

18 SC
22 SH

the set point is -10F but the freezer will not go below 8 F

evaporator and condenser are cleaned.

28oz of 404a

any ideas ?

Again, how do you get a -10f coil with a 42psi suction? Anyone?

[Red850kid]

Oh well, Hondas are overrated anyhow

[ammoniadog]

So is a -10 freezer!