Could be restriction with overcharge plus noncondensibles!!
I fired up the 10 ton carrier unit Ive been working on. the problem is it is a split condensor 5T and 5T identical line sets to the coil one side is running fine, but the other has high head pressure with low suction pressure. this unit is 1yr old. and I did as always install new filters and sight glasses. I also cleaned the condensor as I always do before starting the unit. what else am I missing?
Could be restriction with overcharge plus noncondensibles!!
IT can't be an overcharge, same exact amount went into both sides. It took 1hr. to get to 500 microns, wich I pulled for an additional 1/2 hr. let it sit in vaccum for a 1/2 then charged. some type of blockage comes to mind but what?
Oh I forgot to mention TXV
If it was a restriction the head and suction would both be low and your superheat and subcooling and discharge temperature high.
Give us the model # and are these scroll's and 3 phase?
If you provide pressures, superheat, and subcool.
Rob, ya think he has a scroll backwards?
Notebook is in the work van. I'll get back to you monday with the pressure, super and sub. I actually wrote the model number down this time(I usually don't bother in my notes,and it comes back to haunt me!)
But the scrolls I've seen running backwards have always had equalized pressures. Being a split condenser, I would guess he did not get it as clean as he thinks for the head pressure problem. The txv bulb may be on the bottom of the suction giving it lo pressure. Strictly guessing right now.Originally posted by lusker
Rob, ya think he has a scroll backwards?
[Edited by rob10 on 06-11-2005 at 08:50 PM]
Carrier 10T are not TXV they are acculators (sp?) fixed metering. This thing sounds like a 48TJD012. If it is the high head could be coming from a restriction in the new condenser coil or a factory strainer.
Just the condensors are carrier, the air handelers with the coil are unknown. they date 1984 but all other markings are gone. the coil is a split with twin external TXV's
come on man.. got to make my day here somewhere!
I got pulled off that job, they sent in my senior tech and his outcome was the TXV. he said the tube and bulb were bad. being new to this field, I really wanted to fix the problem. I vissually inspected both TXV's, tubes and bulbs. I saw nothing wrong, no freezing, not pinched, nothing. What did I miss? maybe I just need experience!
You could have heated up the bulb on the TXV to see it the suction pressure would rise. If the TXV was adjustable, maybe it could have been adjusted out, if not it should have been replaced.
As you see, it is tough to diagnose a unit from looking at a computer screen.
Thankyou for your info (writing it in my notes for future ref.) Also it was non adjustable.
Dear Lusker,
Regarding your previous post:
“If the TXV was adjustable, maybe it could have been adjusted out, if not it should have been replaced.”
A TXV should NEVER be “adjusted out” without first determining the superheat and subcooling of the refrigeration system. Nine out of ten TXV’s that are adjusted in the field have been misdiagnosed and subsequently will be adjusted incorrectly. MOST service technicians unfortunately do not posses the knowledge, test instruments, or experience to field adjust TXVs.
Based upon Gunwolf’s original thread information, no accurate diagnosis is possible due to the insufficient information posted; only educated guessing is possible. My suggestion would have been to obtain the subcooling and superheat of the system to determine if a refrigeration restriction was present (my guessimation with the limited symptoms and information).
Gunwolf, I would ask your senior service technician who followed you up on this service call what the superheat and subcooling of the system was and EXACTLY what lead him to make the prognosis’s he did.
Like I tell all the service technicians at the company I work for, if you can’t repair a system, get with the service technician that followed you up and ask him not just what the problem was, but more importantly, how did he find it so you can find it next time.
There’s no shame in not being able to repair or diagnosis a faulty HVAC system, the shame comes in not following up so it won’t happen again.
Just my option gentlemen.
Respectfully Submitted,
John J. Dalton
John, It is just my option that I don’t need your criticism or “guesiimations” of how you would handle things If you were me.
I am very capable of doing my work and controlling my business without your interjections. I am sure that I was adjusting superheat and subcooling long before some here were out of diapers.
I am also sure that Gunwolf didn’t give 100% of the details of the job on his first post to his last. We would have used as much bandwith as you with your crazed "I have to be King and tell them they are wrong" post if we were so inclined.
Speaking for me only, I don't care if you respectfully submit anything that has to do with your observation of this subject mater when I am on the other end and I will gladly ask you to keep your nose out of my business.
Dear Lusker,
What is the problem friend?
Respectfully Submitted,
John J. Dalton
Dear Lusker,
What part of my post are you having problems with? Obtaining subcooling anD superheat before adjusting the TXV? Lusker, I did not say, nor imply you did not know how to adjust TXVs, I merely stated the fact that subcooling and superheat need to be known before ANYONE can properly adjust a TXV. Do you disagree with that?
And despite your posted objections, I am here to learn and not lord over anyone friend. I am truly sorry and apologize for any thing that was said incorrectly.
Respectfully Submitted,
John J. Dalton