Bad TXV

[toy501]

Liebert self contained ceiling mount minimate - Service call system struggling to make setpoint of 70F for data room. Suction Pressure = 68PSIG w/ 35F SuperHeat, Discharge Pressure = 215PSIG w/ 23F Subcool. Sounds like bad TXV valve,(Sensing bulb lost charge or plugged external equilizer). Also possible overcharge by looking at those pressures w/ that amount of Subcool. Also looks like somebody has installed a P66 condenser fan control, In my opinion it's not necessary because since it's self contained condenser in plenum space it's never going to see a low ambient condition. What do you guys think?

[comfortable air]

the suction pressure and liquid line pressure is perfect. if the bulb or plugged external equillier, it could effected the suction pressure and liquid pressure
I don't think it is over change. I am wonder the temperature you measured is not correct.

[madhat]

Was the electric heater and or humidifier on? The relays short and get stuck. What was the humidity, is the room sealed? Where there people working in the room that aren't normally there. Seen that happen, a bunch of IT people start working in the room, door open and closed or worse propped. Temp. goes up, they start going in and out just to check the temperature, and it will never come down. Also look for new equipment. P66 is standard equipment, as Liebert has no idea where these units will be installed, indoors is not always heated.















?

[51fitter]

I replaced 3 of those last month. I think they are way overpriced for what they do. Those p66's like to run the unit 225-250 head. At 250 they kick in full speed finally. I think you might be a little undercharged. For a dropped cieling indoor condenser your head pres should be higher. Maybe double check the superheat and see where it goes with a little more gas. I liked those other ideas of IT people in and out, or if the room is tight or not. If the room hits 70 I'de be on my way home.

[madhat]

You can adjust the P66, just need a Johnson control spline tool. the setting for Lieberts is 225 at the compressor discharge. A control that sticks, is usually oil logged in the capillary. Try removing the fitting, catch the oil in a rag. (it will spray out) reroute the tubing so the coil is in a horizontal plane. and headed down from the P66 to the flare fitting. All Liebert OEM P66 have Schrader valves, and depressors.

[heatingman]

with 23 sub there is plenty of refrigerant, 35 sup is a little high, but not too bad. I would be inlined to adjust the txv to 18 if possible, but I dont think this is your prob. Take some history on the unit/ space. Make sure heat is inactive. Sounds like someone added load and did not tell you.

[toy501]

I'm thinking bad TXV, Removed bulb from suction line warmed in hand w/ no response & put bulb on cold outlet of TXV to see if any change in pressure, No response at all can't adjust superheat as it is non-adjustable OEM (Danfoss).

[The Doctor]

I'm thinking bad TXV, Removed bulb from suction line warmed in hand w/ no response & put bulb on cold outlet of TXV to see if any change in pressure, No response at all can't adjust superheat as it is non-adjustable OEM (Danfoss).

how far off the setpoint is "struggling", as in your original post? If you have to replace a txv in a minimate, at least for the older ones, I'd advise a fire retardant cloth, if ya know what I mean. They jam that valve up in the corner, and that insulation will %$#& up the whole place for a long time!! if you cook it .
I've put in like 2 txvs in mini-mates (having looked at hundreds and hundreds), and soft solder is easier....IMHO

[freonguy]

If your TXV bulb lost its charge, the suction pressure would be low and the superheat even higher ( the ONLY opening force on a TXV ).

What about a '' weak '' compressor ? ie: bad rings or a valve busted ? What is your compressor amperage ? At 68 psi, the amperage should be up there. Is there a suction service valve / will it pump and hold vacuum ? ( bad discharge valve ). Is the can hot ? The discharge sounds a bit low with the P66, but a inefficient compressor will have those symptoms as well.

If it is a 2 piston compressor, one piston may be comprimised and will act like your symptoms. Check 'em out and let us know.

[toy501]

Replace TXV found 1/8" external equilizer line barely in suction line w/ silphos plugging it, Possibly from factory. Pain in da butt to replace tight quarters. weigh in charge,Operation o.k. now 65# w/ 16F superheat & 220# w/ 12 subcool. Thanx for all advice given.