Hitachi utopia cuts out on hot days

[paul_h]

RAS-4HQVE5 R22 fixed speed ducted unit.
Pretty sure it's fault code '41' happening which I retreived from memory maybe (hitachi are rare here), "excessive overload during cooling operation"

How is it judging 'excessive overload'? Comp amps, air thermistors, pipe thermistors, HP or what?

I couldn't get it to trip out on HP, normal HP was 1600-1800kPa, using a tarp over the unit it got up to 2200kPa without cutting out. ST was 5C, DT 79C, liquid line 33-44C (depending if outdoor fans were on high or low speed), while testing at a 26C ambient. O/u air was 28C on, 38C off, indoor 28/16C

[Grizzly]

Hi Paul.
The attached may help?
At a guess I would say something/s are cooking?
Grizzly

[paul_h]

Thanks, looks like it may be outdoor pipe sensor getting too hot under certain conditions.
Doesn't seem like HP fault as I had the unit covered with a tarp to really get it warm, discharge (compressor top) temp always seemed below 80C as well.

So might be the fan speed control playing up, took ages for it to switch to high speed, then it stayed there on high, never cycling.
Maybe a problem with the pressure bypass solenoid? (not sure what controls that) Sometimes the LP dropped low too, when first switched on, and when first switched from low outdoor fan to high outdoor fan, but it recovered after a couple of minutes and the suction temp was always around 5C and the discharge temp under 80C. But the bypass valve operation might have something to do with that? Didn't seem like a blockage or restriction anywhere. I'm not up with how the bypass valve is supposed to operate as I've only looked at 4 hitachis before.

Do these things have to start on low o/u fan for a min time, or can they start at high speed straight off the bat?
What temp does the liquid line sensor read up to before it cuts out on outdoor overload fault?

[Grizzly]

Paul.
I have tried to find more info but have drawn a blank.
Your observations make absolute sense, but as to the settings who knows?
Maybe someone else can help further.
Sorry Grizzly

[al]

Paul

Sounds like it's not using medium speed, i'll try and dig out a manual later.

alec

[install monkey]

paul-utopia r22 manuals are like rocking horse poo- if found a technical manual with a bit of info,also some other utopia manuals-
https://rapidshare.com/files/2458699...2_TCGB0004.pdf;
https://rapidshare.com/files/3118847...ice_Manual.pdf;
https://rapidshare.com/files/1678891..._technical.pdf;

filesize 14-102 meg took 30 mins to upload!

[install monkey]

hold check button for 10 sec to scroll through sensor values

[assailant]

Paul, I have a hardcopy technical catalogue for the Hitachi range that the RAS4HQE5 is a member of but it doesnt have any trouble shooting, only tech data.

im guessing you have a Robertson LD-LM5 attached to it?

I have digital copies of manuals for Hitachi Utopia G7 outdoor units (the later series R407c).

I can request some data from Temperzone if you like?

[paul_h]

Hi assailant.
I do have a generic manual for old upotias, the same one install linked to "...TCGB0004.pdf", which I got from his hitachi.eu link he put up a while ago elsewhere. It was from that I worked out from the limited information (and the fact it only cuts out on high ambient days), that the error is 'overload on cooling mode'

Kind of a generic fault, that I need to track down on what inputs tell it to shut down in the fault mode, and then work backwards from there.
For all I know it's either an outdoor fan problem, PCB, or something else like a bum sensor. The sometimes low suction pressure but decent temps on the suction and discharge have me confused too. (as well as decent HP)
So anything that tells me the max values of any thermistor can get to before shutting down, or anything else (could be max times the bypass solenoid is operated for instance) get too before it shuts down on that 'overload' fault is what I'm after.
ie If overload = compressor temp of 110C, or liquid line of 50C, or whatever, plus their resistances or voltages at those temps so I can see if it's just a thermistor fault or a refrigerant flow fault etc.

[rude]

Does the unit have a sensor on the compressor measuring compressor temps? If so that could be an issue. Also i remember someone telling me that the hitachi compressors get really hot and if they have the insulation around the compressor, remove it and that apparently helps.

[Kaiser]

Hello Paul_h

Utopia Series 5 fault codes below

https://rapidshare.com/files/3582938...es_5_Codes.pdf

Regards