Liebart System

[twisted22]

So here's the senario: I showd up at a server room about 2:00pm and the Liebert a/c system was off on high head. I was pretty sure that the (remote condenser) coil wasn't plugged cause I had blown it out myself less than 2 months ago. It's an R22 system and the gauge read around 350 psi on the LL (ambient is 88 degrees). It would creep to 370 and trip. After adjusting the fan blade in the shroud (an apprentice had installed a new condenser fan motor 3 months ago) nothing really semed to matter. Another tech had replaced a plugged tx valve on it a month ago but it had been working well until today. He said that he had checked the superheat and subcooling and had set the valve up for 8-9 degrees superheat and all was well. The chance of non condensibles seems really remote and if I pour some water on the coil the head pressure drops like a stone to 230. Suction pressure is 60-70psi. Is there anything I might be missing beore I rip out the charge and replace it with (for sure) clean refrigerant? Thanks in advance.

[goshen]

hi there check the replacment fan ,
it would appear it is not the same as original( less cfm ) or possibly reversed in direction !
let us know how it turned out

[Gaafar]

if ambient is 88 then condensing pressures looks very high and since tx is replaced there may be air in the system it must be bleeded if possible from a relief valve or you have to recover refrigerant and evacuate and dry the system and then recharge

[TRASH101]

Goshen sounds to be on the right path

Before recovering the refrigerant check the condensor again
i.e. air on and air off temps and volume of air across the coil.

Also check for dead rows (indication of non condensibles)

It might just be all the packing material from the new fan blocking the coil

[iceman007]

I remember years ago having a similar problem. It turned out to be a faulty pressure switch (head pressure controller) It wouldn't cut the fans in.

[twisted22]

I haven't been back there yet this morning, but I will check the fan motor. I thought it was ordered directly from Liebert as a replacement. There is no place to bleed air from the system so the refrigerant would have to be replaced. I will check for dead rows on the condenser coil but there was a ton of heat coming off it last night. I WILL cure the problem today and let you know how it turned out. It has to turn out good... today is friday.

[TRASH101]

I WILL cure the problem today and let you know how it turned out. It has to turn out good... today is friday.

And if you listen very carefully a solitairey bell tolls in the distance, amidst darkening skies as the sunlight is obscured by the ominous thunder heads stampeding from the horizon.

[twisted22]

And if you listen very carefully a solitairey bell tolls in the distance, amidst darkening skies as the sunlight is obscured by the ominous thunder heads stampeding from the horizon.

Yet a single ray of sunlight peeks thru stark blackness and a chorus of singing angels gently serenade the dawning a new day ... Okay, I myself didn't make it back to this job but I did dispatch an apprentice to recover and replace the charge. When I phoned him to see how the task was going he said good but the vacuum was proceeding very slowly. I then realized what was wrong. The tech that replaced the tx valve didn't energize the solenoid valve when he was pulling the vacuum. Once I told him to disconnect the compressor contactor and turn the unit on to open the solenoid the vacuum dropped like a stone. The charge was weighed back in and the head pressure dropped to 220psi. All is well but then why wouldn't it be ... it's friday!