Sanyo multisplit problem

[marc5180]

Been sent over to a unit today that is having problems with one of the unit not heating.

Sanyo SAP-CMRV3143GJH Multi DC inverter

Got over to the site and found poor heating on all three units, switched over to cooling and again poor preformance on all 3.

Put the gauges on and on heating and the hot gas line pressure was 15-17 bar on R410a.

2 of the units seemed to be getting 30 degrees on the line going to the indoor but the 3rd seemed to be getting no heat.
The indoor fans hardly run on heat, i imagine to try and increase the discharge pressure.

I've been told that these units are mostly used in domestic so they are a pretty basic unit.

I need to know if these have a target discharge pressure say 28bar and if so what controlls it since i cannot get the discharge above 28 bar.

I have checked the temp difference across the 4 way valve and its ok as well as the discharge sensor and ambient and outdoor coil sensor, all seem ok.

I can't check the frequency of the compressor only the amps it is pulling and they are 12 amps which make it look like the compressor has ramped up but something is stopping the discharge from increasing the pressure and since i don't often work on these units i'm not sure what.

[El Padre]

Never seen one of these but the indoor fans probably need the coil to reach a predetermined temperature in heating before they start, did you measure subcooling and discharge superheat? sounds undercharged.

Cheers

[marc5180]

it does sound undercharged but the gas was weighed out earlier. there isnt a stub on the liquid line so cant measure subcooling.
the discharge superheat was at 2degc but after 20 mins or so of operation increases to 30-40degc.
the suction superheat varies but at the minute is reading 2degc

[Brian_UK]

Tech manual if you want one Marc.

http://www.oceanairdist.co.uk/assets/pdf/service/Sanyo/Service%20Manual%20SAP-CMRV1923GJH%20SAP-CMRV2433GJH.pdf

[El Padre]

Hi Marc,

Just a thought, but have these units definately worked in the past? Could there be a problem with the pipework, too long, wrong fittings etc? If they are basic units they probably won't work in cooling mode at our current ambient temperatures, for subcooling detract the liquid line temperature from your saturated discharge temperature which is somewhere between 20 and 30 degrees, no comparator handy!

Cheers

[marc5180]

Thanks Brian,

El Padre, yes the units have worked fine for the past few years.

I compared the readings with an identical multi at the side of this condensor and with just one indoor runnning the discharge ramped up to 32bar straight away, the one i'm working on stays between 16-18bar about 30DegC (roughly) and the gas charge is correct.

The only things in these units is a 4 way valve and 4 eevs (1 for each indoor unit) and a defrost solonoid which also seems fine..

[El Padre]

So you have checked the compressor,thermistors, transducers, refrigerant charge, reversing valve etc. Must be some sort of flow problem, do they work if you only turn on one unit at a time? Got me stumped, sounds like a job for Thermatech!

Cheers

[marc5180]

Yes we have checked everything we can think of, all sensors included and they all come back ok.

The compressor would run at around 10amps and then all of a sudden ramp up to 15 and then come down to 10 and then back up to12 then to 14 then to 10 then to 17 all within a few seconds and the compressor just didn't sound healthy.

Sometimes they work on cooling, sometimes they don't, all 3 will not work on heating though.

We have tried just running one indoor at a time but it makes no difference.

As soon as i figure it out i'll let you know.:)

[Thermatech]

I know the systems have been installed for some years
but
from time to time I find crossed pipes & control cables between systems which have never been found even after years.
Only this month I was trouble shooting some VRF systems which had been installed for over a year. A number of engineers had tried to resolve poor performance problems & it had got to the stage where the contractor was not able to get retension payment because customer still not happy.
We found crossed pipe & control cables to be the cause :cool:

If the outdoor unit has LEV valve for each indoor unit then the only place for refrigerant bypass is at the outdoor unit.
unless
crossed liquid & suction tubes between indoor units connected.

Have you ever had multiple split systems with crossed liquid & gas tubes between systems ?
like
from the outdoor unit the liquid goes to one indoor unit & the gas goes to another & then the refrigerant does a figure of 8 arround the two indoor units & the two outdoor units.
Crazy mind bender to trouble shoot :confused:

Marc
To eliminate crosed pipe & control cable to other systems turn off all the other systems & just run this one system & see what happens
or
run all the other systems in test heat & run just this one system in test cool & see what happens at the indoor units.

[marc5180]

Thermatech;

The unit has been in for 3 or 4 years and this is the first time they have had any problems with it or so i am told.

They have 2 multis each with 3 indoors on.
1 is at one end of the building and the other is at the other end.
Theres no way that these 2 systems could have got mixed up but as you say crossed pipes from the same condensor could have happened....surely someone would have noticed by now.
I also found out that Sanyo came out to site to commission these surely he would have spotted it.

I've never come across multiple crossed units yet, thats not a day i'll be looking forward to.

[back2space]

Have you had any resolution to this?

[airconadam]

Sorry for not replying sooner,We went back to site a few days later after the original post and ended up swapping all the pcbs on the outdoor unit (A) with an identical system,after swapping all boards and sensors we tried running up system(B) which now had the boards from unit(A) that ran fine with no problems.We now knew it was nothing to do with the boards or sensors,when we tried running unit (A) it tried to run but wouldn't start the compressor? all the compressor would do would jolt and bang a little as if it was seized power was going to all windings and the amps were 5-8? after a few times of trying to start it would then fault and go off on a compressor rotation fault. We then spoke with sanyo and he said yes the compressor is knackered but its now cheaper to replace the whole condenser than the comp????? but still if the compressor was on its way out would that cause the comp not to ramp up and to stop the pressure form raising??

thanks alot

adam