Need help On walk in cooler

[markvilleman]

I got a call: a walk in cooler not cooling.it is a 2 hp water cool condensing unit with a liquid receiver and 2 tons indoor coil,the tev is danfoss tx2 model and the orifice is #4, R22 system.
The coil was build up with ice when I got there.After the ice melt and start the unit. The hi side pressure is 170 psi and low side pressure is 28psi. The outlet water temp is 75f and inlet temp is 47f. Adjust the water regulater and set the outlet temp to 90f. The pressure go to 200 psi and 30 psi, the super heat is 50f and the sc is 16f. Ice start to form again. Checked fans and comp,volt is 116v and 230v, 0.5 amps for each fan and 4.6 amps for comp.Check filter drier,side glass,no restriction.replaced the orifice for the tev. It had the same problem. Top up with 9 oz r22, the suction pressure up to 33psi and liquid line pressure is 225psi. The super heat is 48f and the sc is 46f. And the liquid line became cold. Hold the bulb of the tev, the suction pressure went up to 36 psi, Is the tev not good and why the sub cooling went up and liquid line became cold? Thanks .

[thermojohn]

The SH is high. The TXV needs adjusting to decrease the SH. Where are you reading your suction temp? At compressor, or evaporator outlet?

SC @ 16 is a little high also. Is the SC after your work really at 46 or is that a typo?

What is the box temp with these readings?

[markvilleman]

yes, I had adjusted the tev, if I turn the other way, the suction pressure will go even lower.the suction pressure i measured at the out let of the coil. the sc is 46f, i measured at the outlet of the reciever and the temp i got it from the outlet of the condenser.

[markvilleman]

the box temp was at 60 f and it had high humidity inside.

[thermojohn]

You definitely have flow problems. If valve adjustment isn't working, then it's time to replace the valve.

Keep in mind when adjusting txv superheat, you are looking more for temperature response than pressure, albeit your low pressure here is way too low for a 60 degree box.

[jackintheboxtec]

Is your sight glass full?
Evap coil clean?

[hvacpope]

sounds like the TXV is bad,the Danfoss made in china are notorious for failing that way, replace it with a Sporlan.

[markvilleman]

Is your sight glass full?
Evap coil clean?

yes,the coil is clean and the sight glass is full.

[markvilleman]

You definitely have flow problems. If valve adjustment isn't working, then it's time to replace the valve.

Keep in mind when adjusting txv superheat, you are looking more for temperature response than pressure, albeit your low pressure here is way too low for a 60 degree box.

I agree with that. When I adjusted the txv, I checked the temp change at the suction line. Its super heat value getting even higher.

[engineerdave]

Think I gotta go with Jack on this one. Are you SURE you're not leaking somewhere?

[markvilleman]

Think I gotta go with Jack on this one. Are you SURE you're not leaking somewhere?

Checked all joints with liquid detector and its clear. Vaccume the system and it hold for more than one hour. So far,....yes.

[baub]

And the liquid line became cold. .

Tell us more about that... how cold, frosting after the drier?

[jpsmith1cm]

I wouldn't worry a whole lot about subcooling on this system. Particularly not as a measure of charge.

Get the sightglass clear and call it good.

I would agree that you aren't moving the refrigerant that you need to. Cannot confirm TEV or Drier, but you are on the right track.