hitachi utopia g7 r404a not up to cooling

[peter1927]

hello all , just had a look at a big hitachi utopig g7 ducted unit using r404a gass,cust reported not cooling, our door temp approx 30 deg , suction 445kpa , liq 1670kpa.

unit was not cooling at all when arived, i made a boo boo checking voltages on control board on 12v reg ( i shorted to ground and reset unit), when unit came back on seamed to be cooling a bit ,( as per above readings).
but just not got the grunt behind it. as though it is set on low speed ( fans inside to vary with selected speed on controler), water draing on inside unit (went in roof and seen).

used inside a 15 meter by 15 meter shop for butcher/takeaway shop windows down one side and door open.

any idears why this unit not preforming ?

[iceman007]

Because it's under condensing. Outdoor temp is 30 degrees. You need a condensing temp around 45 degrees upwards, 16.7 bar head pressure corresponds to a sat temp of about 38 degrees, so I would guess you have flash gas in the liquid line from the info you have given so far.

[frank]

Hitachi on R404A? :confused:

[iceman007]

I thought that as well Frank. Perhaps it must mean R407C, because the G7 range in Australia runs on that.

Peter 1927, are you certain about the refrigerant ? Or is it R407C

[iceman007]

Also if you haven't worked on the unit before, it may be worth going back through the history, and making sure no repairs have been done to it, involving refrigerant charging, because if it is R407C and someone has vapour charged it, or added to it then this sort of thing happens. I had it happen to me a few years ago when someone had done that R32, which is the most volatile component of R407C would be the majority component in the a/c, and it has a lower boiling point than the other constituents (-51.8 degrees I believe) meaning it would need to condense at a higher pressure than what you have. Usually you can tell because the compressor will be running hotter.
Just a thought, but I would check it out-If you want I'll come over and look at it for you. I need the warm weather and beer LOL !!!

[fernbay]

LOL Iceman

I was with Pete.
It is definatly R404A. The factory stickers say so.
I hear that 5 ppl's have look at this unit so far.
The owner was told 'It has gas'
I don't know how they came to that conclution (pressing a pin valve maybe?)

He sais the air off temp is 26 & no better (keep in mind it's summer here) - was 30~35 (40 or so midday - heatwave stuff ;).
I looked at it with Peter about 2 hours before sunset, unit in sun.
I also suspect under charged. No sight glass :(
I'll see if I can get some more history on it.... BRB :)

[iceman007]

Can you give the system model reference number. If you are running a suction pressure as mentioned, the coil should definitely be running cold enough, but if the air off temp is so high, I would start asking whether it's sized big enough to do the job (but saying that your low side pressure doesn't sound high enough to be that)
Or the other alternative, recover the charge vac out and weigh the correct amount back in (once you have confirmed there is no leak)

[iceman007]

On the catalogue for the G7 range in Australia-from the Hitachi website, the whole lots on R407C unless the info is out of date. I wonder if it's got the wrong refrigerant in, because I can't see how it can run on 404a

[fernbay]

I can send you on-line the book 318 pages G7 Utopia R407C but it is 13 mB and i am allowed to upload only 10 mb (I don't know how to compress it):D

I would love a copy mate :)

The email is dave@householdelectronics.com.au
The best way to compress it is by installing winzip or winrar & then you can right click the file (or folder or pdf etc) & compress it from there. It even has a option to split the archive into managable chunks ;)

I've been searching for a halide lamp colour chart to see if I can positivly identify exactly what the unit is charged with, but can't seem to find one. Anyone got a link to one that they can post?
The sticker might be right, could also be wrong, but this thing has had 5 other techs at it, so anything is possible :eek:

[frank]

Help yourself http://www.swm.co.uk/Hitachi_Rac_Utopia1.html

[fernbay]

Thanks for the link Frank. Much appriciated :)
I'll figure out an answer to this one yet :p

[iceman007]

I've been searching for a halide lamp colour chart to see if I can positivly identify exactly what the unit is charged with, but can't seem to find one. Anyone got a link to one that they can post?
The sticker might be right, could also be wrong, but this thing has had 5 other techs at it, so anything is possible :eek:


A halide lamp will only work on chlorinated refrigerants. If you want to identify the correct one, then hook the gauges up (with system at rest) check the pressure that corresponds to the ambient temperature-use a comparator. So for example at 30 degrees R410A would have a pressure of 260psig, R407C is less at about 170 psig or so, give or take.

[fernbay]

Thanks Iceman. I'll try that.
I use to have a chart of flame colours. Dammed if I can find it. I'll give up looking now 'cause it's not going to help :D