mr slim p8 error code

[Krups]

anybody got any ideas with this 1...

set up = 4 x mitsi elec mr slim large cassettes
indoor - PLH - 5GKHV
outdoor - PUH - 5YK2

all run off 1 remote control...

3 units run fine in both heating and cooling...

unit no 2.... doesnt kick in....no leds on pcb outsite...compressor sounds fine...

error code on remote is p8

misti elec tech guy said "check the outdoor board"

i thought i was playing give us a clue...

asked again for bit more details - "check the outdoor board"

now interestingly, the bypass solenoid valve is quite burned out, il post the pics in abit...

and the liquid reciever is quite burned also...

any 1 got any ideas please ?

[frank]

Hi Krups

P8 means "Abnormality in Outdoor Unit" that's why the tech guy has told you to look at the outdoor unit.

Possible causes
1 Wrong wiring of Indoor/Outdoor connection
2 Reverse Phase
3 Protection Device operated
4 damaged Outdoor coil thermistor

Areas to check

1 Check continuity of the interconnect wiring - look for breaks (I've had it where rats have chewed the wiring before :eek: :eek: )

2 Check the phase rotation - has any work been done on the unit mains wiring?

3 Has any safety activated? Compressor klixon? LP switch? HP switch, Fan overload? etc.

4 Measure the resistance of the coil sensor

If you are still struggling then give Mitsi Technical a ring 08703000300

[Krups]

hi, just found this thread aswel that relates to it..

http://www.refrigeration-engineer.com/forums/showthread.php?t=877

i noticed u said here, it could be caused by hp fault, more often than not caused by dirty indoor filters,

well when i got here, the filters were some of the worst iv seen, had not been cleaned in at least 3 years i was told...

and the system had been left on heating for the last few months due 2 weather..

also as no leds are lit...
surely that can rule out check point 1 on ur list above ?

check point 2 - will do that.

check point 3 - not sure - also needs looking at.

check point 4 - what readings am i looking for ?

btw this is 3 ph.

could it be a faulty pcb ? as no leds light up ?

i notice alec posted this -

Is it a 3phase condensing unit?If so p8 can refer to phase imbalance or rotation direction, try swapping two phases.Inside of condensing unit cover should detail led faults, are any flashing?Could also be loss of charge or faulty boards

also - as that soleniod is extremely melted...would that be a culprit ? what can cause that to happen ?

@ aiyub - u never did post how you got on...

[aeb200]

P8 is not just an outdoor unit fault!!!
It is triggered 15 mins after a heating/ cooling signal has been sent to the outdoor unit and there is less than
5oC differential between room sensor and indoor coil sensor. Sensor errors can also produce a P8

Anyway most P8's occur when there is a power cut on site - outdoor unit thinks its lost a phase so shuts down. To reset just turn outdoor isolators off to all outdoor units, wait 10 secs, then switch back on again.

If the outdoor unit has a fault on it you'll find a list of led sequences on the inside of the cover-
On old R22 systems there are eight (one will be flashing), on 407c/410a systems there is a red and green led. If you have missing phase defect reset power, if you have th4 (discharge) too high it is likely that you have a leak- these are the 90% of Mr slim probs that i come accross

[frank]

The solenoid coil? If the coil is taken off the valve stem then it can't dissipate it's heat and can burn out. Also, if the valve is running for any length of time extremely hot due to high discharge pressures/temps then the same thing can happen.
Of course it could just be that the coil is knackered ;)

My guess is that the indoor filters have been heavily contaminated and the compresor has been running hot leading to a HP trip.

It's probably nothing to do with the phase rotation as the other units are working. You can swap the outdoor coil sensor with one of the other units to prove that it's working and it's fairly simple to do a continuity test on the wiring.

[Krups]

it is an R22 system...

[aeb200]

unit no 2.... doesnt kick in....no leds on pcb outsite...compressor sounds fine...


Does the compressor work or not??
do you know that you should never push contactors in on a misti / daikin / tosh etc.

to test outdoor board you can check that you have 18v ac on the interconnecting wiring - this shows that you have an output at least. All boards have fuses and ZNR's check them!!

If you push sw1 (i think) you will see the last led fault code- if the sun is shining on unit you may need to get in close to see which led is flashing

[Krups]

didnt know that you should never push the contactors, was taught on the job, that its fine...
just out of curiosity,y is it there then ?

i pushed sw1, and sw2....
but nothing happened...not sunny dwn here in leicester im afraid...

[aeb200]

on all mitsi/ daikin there is tape over contactor that say "don't push in" you must have torn this to push in.

I think that you may get back feed that can effect pcb etc. Also on some models pcb controls compressor rotation (i think) so you may damage it!!

It is alright to push in contactors to most other fridge stuff, but japanese ac units with pcb's are a no no!

I still think you may want to reset power to clear fault then put guages on if unit runs, get yourself a solenoid magnet to test the valve. Also if site (or unit ) has lost a neutral it will blow ZNR (blows at 550V) make sure this hasn't blown (it looks like a green leaf) -if it has check neutral and replace outdoor pcb

[Peter_1]

Does the compressor work or not??
do you know that you should never push contactors in on a misti / daikin / tosh etc.

It's always the first thing I do to see if compressor is still running and if there is power supply to the unit.
The only reason I see is that the compressor runs then in reverse, that's all.
Back feed to the PCB??? You're only making a contact on the main leads to the compresser.

[Brian_UK]

i pushed sw1, and sw2....
but nothing happened...not sunny dwn here in leicester im afraid...SW2 shows fault codes, SW1 clears fault codes I think, get them the wrong way around and the fault could be cleared before you get a chance to see it.

[Krups]

oops lol iv pressed them both neways...
but the leds didnt work neways...
so ....
guess it never made a diff ?

[rbartlett]

P8 was nearly always a refrigerant leak for me..

cheers

richard

[techguy]

HI Krups ,
If there are no led's on the outdoor check the transformer. they go down reg.
regards
T

[Scooby]

Lo all...

Sparky in my first life doing a/c ..refridg now for almost 10 years and i have never understood why it is so tabbooooo "NOT" to push that contactor on some splits...
must agree with peter in that it is the first thing i usually do also...... how else do you tell if the comp is running especially if the units are a 20 min hike away from each other...........

sorry to deviate from the original topic

best advice i can give for a Mr Slim is bin it and fit a daikin......:) :) :)

:p