ReplyWhat is the model and serial number of the condensing unit/ evap coil?Originally Posted by Dewey HVAC
What is the superheat value at the compressor?
Regular Guest
Hello. I am an HVAC contractor. I haven't done much refer work, however I recently installed a walk in cooler system. My issue has become a low head and suction pressure. (140/15). The system is a 404A unit. I installed a 3/8" liquid line and a 5/8" suction line. I have a solid ice cube at my txv, and cannot get either pressure to rise. Sight glass is clear, and walk in cooler drops to 39 degrees with no problem. I did adjust the pressure switch just to keep it going because if it satisfies the t stat, it begins to cycle of and on at next start up. It then just short cycles continuously on the LPS. Any advice would be helpful. Thanks!
Professional Member
What is the model and serial number of the condensing unit/ evap coil?
What is the superheat value at the compressor?
Professional Member* / ARP Committee
Is the condenser indoors or outdoors and what is the ambient temp?
Officially, Down for the count
YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET
I know enough to know, I don't know enough
Why is it that those who complain the most contribute the least?
MONEY CAN'T BUY HAPPINESS. POVERTY CAN'T BUY ANYTHING
Professional Member*
Superheat and Sub Cooling #'s.
R I P Icemeister
Supporting our Vet’s
http://www.soldierride.org/
http://www.woundedwarriorproject.org/
Professional Member
Restriction before/at the metering device? That's my guess. What's he mean when he says "i adjusted the lps to keep it going">? Is it running continuous now? I confused
Global Moderator
At 15#'s suction I could see it cycling on low pressure however if this is a pump down system I would probably set in closer to 5 psig.
How many pounds of refrigerant did you put in and what HP is the compressor ?
Of course knowing the answers to the other questions presented here sure would help eliminate some guesswork 😉
Regular Guest
Condensing unit MOD# CCH0010MCACZ SER#T21M21245
Evaporator MOD# BEL0115AS6AMAD SER# T21K23890
Not sure about super heat at this moment.
Regular Guest
Condensing unit MOD# CCH0010MCACZ SER#T21M21245
Evaporator MOD# BEL0115AS6AMAD SER# T21K23890
Not sure about super heat at this moment.
Condensing unit is outdoors... roof top
Used an initial charge of 9 lbs, however, I will say I have added quit a bit more trying to bring the pressures up.
On initial start up, I was not having this issue, pressures seemed a bit low, then suddenly this happened.
I adjusted the LPS because when the unit starts, it will cycle off and on rapidly because the suction pressure will not rise. so, I adjusted the differential so it will run.
It is a pump down system, and it is cycling on the t stat as we speak. in other words, it is operating, but not properly.
ALSO, I know, I know from all of you... I have made several mistakes, but I want to hear about them as I love learning.
Professional Member*
Thats not how you do it!!!Once the SG is clear Thats IT.
We need the SH readings at the outlet of the evaporator and about 6" before the compressor.
Take temperature readings across the drier. Should be less then 1°F.
Is this a Pump Down System? I hope so.
The LP control was doing its job.
R I P Icemeister
Supporting our Vet’s
http://www.soldierride.org/
http://www.woundedwarriorproject.org/
Professional Member*
And order this Book Today:
https://www.amazon.com/Commercial-Re...45014266&psc=1
R I P Icemeister
Supporting our Vet’s
http://www.soldierride.org/
http://www.woundedwarriorproject.org/
Professional Member* / ARP Committee
Standard unit is micro channel with a 140 headmaster. At this point it sounds like evap is starving.
https://products.heatcraftrpd.com/dA...f/CC-PC-PL.pdf
Officially, Down for the count
YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET
I know enough to know, I don't know enough
Why is it that those who complain the most contribute the least?
MONEY CAN'T BUY HAPPINESS. POVERTY CAN'T BUY ANYTHING
Regular Guest
Ordered the book. Thanks!!!
Global Moderator
What's that evaporator branded ?
Regular Guest
heatcraft
Professional Member*
There is probly a screen at the TXV .... and it might be dirty
But are you sure the sight glass is full .... not completely empty ? Sometimes they will trick you
Whats the outdoor temp ?
Tell your Cat I said "Psst Psst Psst"
It seems like everywhere I go the AC is broken
Professional Member
Txv probably is flare. Pump the system down and remove the liquid line connection from the valve. It might have a strainer/screen on the 3/8 inlet that is plugged up. If the system is running a high suction superheat, there is not an adequate amount liquid being distributed to the coil, which would account for your low suction pressure, low coil temp and high suction superheat if present.
Professional Member
During the initial setup,
Did you use a dry nitrogen purge while making connections?
Did you perform a triple evacuation and use dry nitrogen to break each vacuum?
Moisture in the system may cause some headaches.
Banned
What TXV is in the evap?
Regular Guest
Yes, I purged, pressure tested. And triple evacuated with nitrogen. I am very particular about the installation of equipment. Not that it makes me special, but just to explain how particular I am, I average an install of air conditioning equipment per day. Whether it be a heat pump, A/C, furnace, etc. I have not had a call back in over 5 years. My point... I applied all the specific install techniques to this install as I do to all others. I have only installed one other refer unit before though, and it was much more clear cut than this. It was pretty much a hook up and go. I also feel there is a restriction at the TXV. It is sweat on, and not sure what to do other than maybe cut the line and try to blow nitrogen back through it. ??
Banned
If this is a regular (non EEV) TXV then the TXV needs a higher minimum hiside pressure.
Posting Permissions