DAIKIN multi split fault

[leegally1983]

Hi guys can anyone help I have a Daikin multi system 4mxs80e7v3b1 with 4 cassettes one of which is not heating and cooling most of the time. The other three heat and cool perfectly and sometimes the other unit works fine but seems to be only when the others are on aswell. I pretty sure it's not low on gas as the pressures seem there or there abouts. R410a. Changed the expansion valve head for one which works buy no success I ran out of time on site tho so was hoping someone could help for the next visit??
thanks

lee

[The Viking]

Sensors?
TEV body?
Strainer?

[leegally1983]

Pretty sure the strainers are ok as the other units work fine, valve body I'm not sure as they are hard to test esp the fact that it works intermittently and the sensors all seem fine

[install monkey]

lev on outdoor not motoring open- swapping the heads wont cure it, and if your using all 4 ports u cannot swap circuits to proove this

[leegally1983]

I think the fact that it works sometimes is stumping me as surely if the EV was not opening it would never work??

[The Viking]

I don't know what indoor unit's you got but Daikin sometimes put strainers inside the pipes just behind the flares on the indoor units.
Seen it in the past where moisture in the system get stuck in this mesh and creates a blockage when it freezes.

Unlikely but something to bear in mind.

[leegally1983]

Thanks I will look into that

[RusBuka]

Yep...if EEV in indoor and strainer jamed you hear gurgle in cooling mode, if EEV in outdoor temp. before and after strainer different.

[frank]

Is the total pipework length within 75m?

Is the troublesome cassette within 25m of the outdoor unit?

[Slim R410a]

Had the same problem last year on a 2MXS50F - ordered both expansion valve body and valve coil turned out it was just the coil in the end so 10min job.

However had this on Daikin RK/XS splits in the past and turned out we had to replace the valve body so could be this or as Frank has said above.

[leegally1983]

FRANK The total pipe runs are border line 75m and this unit is about 20m, why can one unit not be more than 25m??
SLIM yes I was edging towards the EV body as I have had many Daikin units in the past with dodgy valves body and head seems common fault tbh

[frank]

FRANK The total pipe runs are border line 75m and this unit is about 20m, why can one unit not be more than 25m??

It's all about pressure drops...pipe resistance to flow etc...

Manufacturer's make the rules, we just have to live by them...

[r.bartlett]

It's all about pressure drops...pipe resistance to flow etc...

Manufacturer's make the rules, we just have to live by them...

Or not if needs arise :-)

[leegally1983]

Managed to get back on site and have a play around with the unit again looks like its the valve body there is just nothing coming through it, thanks for your help guys

[RusBuka]

Did you check step motor?

[leegally1983]

step motor?? do you mean the expansion valve head/motor?

[RusBuka]

Yes, i mean that) If you can change heads on working unit, do it) And look what happend with bad indoor unit.

[leegally1983]

Hi Guys

Bit of feedback, i went to site and there was a spare port so we swopped the faulty circuit to the spare one and re-commissioned it and the faulty indoor unit worked.
We left site anyway we have had a call today saying it now has a U0 fault which means low pressure, faulty exp valve, faulty low pressure sensor or blockage.
This seems strange as we left all units running fine and pressures were good so i am abit bewildered by this we are going back to site tomorrow to have a look any suggestions?

[bigspee]

Blocked strainer?? Faulty pcb?

[install monkey]

had it on a daikin multi split U0 error- get the hose pipe on the condenser, visibly looked clean but got a load of crap outta it, then check the charge- also which unit is designated as a master?? - outdoor dip switcha-d if u swapped port and that was a master then that wont help, im assuming u swapped the wiring over too

Hi Guys

Bit of feedback, i went to site and there was a spare port so we swopped the faulty circuit to the spare one and re-commissioned it and the faulty indoor unit worked.
We left site anyway we have had a call today saying it now has a U0 fault which means low pressure, faulty exp valve, faulty low pressure sensor or blockage.
This seems strange as we left all units running fine and pressures were good so i am abit bewildered by this we are going back to site tomorrow to have a look any suggestions?

[leegally1983]

when I got on site I found some bright spark had the central heating on with a rad in his office and because he was too hot instead of turning down the rad he decided to put the unit on 16 degrees cooling and then left his office door open poor unit had been running flat out all day .................. bit of training for the customer problem solved thanks for the help guys