Mitsubishi PUHY-250YMF-C

[Yuri B.]

Could someone tell me please why VRF Mitsubishi outside unit PUHY-250YMF-C does not bother to start its compressor (the demand must be present as there is 30C with set point 19C in the space it serves) ?

When I switch power on, the 4-digits display on its pcb shows "8,8" (1-st and 2-nd digits) for about 15 sec, then "51" (3-rd and 4-th digits) for about 3 min, then for all the time there are "1" in the first digit and "1" in the 4-th one. Actually it is three PUHY' system - other two doing good duty for their spaces. The digits on them show also two "1"'s - only the first "1" takes the left vertical segment(s) of the first digit - while the problematic PUHY's one takes the right segment. The second "1" takes the right vertical segment of the 4-th dig at all units.

Have "belled" the windings - looks normal, 3-ph supply balanced, neutral Ok.

I knew nothing about Mitsub, let alone its VRFs untill today, am searching now internet for indications, deep switches settings, etc - with no success (Mitsi's motto : no money = no manuals).

Have read all threads about Mitsi's here - maybe, indeed, nothing to do to them without laptop with Mitsi's diagnostics software?

[imran ansari]

check pcb and safety switches

[Yuri B.]

Thank you Imran Ansari. You are right, there indeed should be a HP klixon - forgot yesturday to look for it. PCB's fuses good, a small lcd indicator on it shows 8,8, then 51, the 11. Cannot find any info yet about that "PUHY".
Room wired control PAR-20MAA, but as I knew nothing about it too, pressed yesturday its "check" and "test" buttons and have not made any sense of indications. SP was 19C, mode cool. Can I see on it faults of the outside unit?
There is no central control.

[Thermatech]

When 3ph power up the outdoor unit looks for all indoor units connected & completes an electronic hand shake with each one.
While it does this it will display its own address ( in your case 51 )on the outdoor display & normally takes about 2 mins.
Then when complete the right hand 8th flag will always be on to indicate outdoor unit ready to run.
The 2nd flag from left indicates crankcase heater on.
When any indoor unit requests cooling the 1st flag will be on & the compressor will start.
4 digits = 8 flags. 1 at far left , 8 at far right.
The size 250 only has one compressor.
If the outdoor unit had HP fault it would show a 1302 fault on the outdoor display & would start again follwing a power reset.

At minimum you need a service manual
then
look for why the outdoor unit is not getting request to operate in cooling mode.
The service manual is 200 pages.
You can get all the system data from the outdoor display & SW1 dips but first you need the service manual.

[Yuri B.]

Thank you Thermatech.
I have found smth - what one should order and pay for in order to download is detailed and clear, what is free, seems to be simplified and less clear.

Anyway, not clear to me yet what may at all be difference between
R2 series (compressor technology),
R2 YRF series,
Y-series,
Y-series using R2 series technology,
S-serie ?

Even not clear what is the diff between
PUHY,
PURY,
PUMY ?

[Thermatech]

The Mitsubishi Electric Y series City Multi 2 pipe heat pump systems are a multi split system much like other 2 pipe heat pump VRV / VRF systems.
The models are PUHY heat pump
or PUY cooling only
Latest R410a products up to size 1250 about 140kw nominal cooling capacity.

The heat recovery R2 City Multi system has a BC branch selector box.
System can do cooling at some indoor units & heating at other indoor units at the same time.
Any heat recovered from the indoor units in cool mode is transfered to the units which are heating via the refrigerant but still only using 2 pipes.
All other VRV / VRF manufacurers use a 3 pipe system for heat recovery.
All R2 heat recovery systems are model PURY.
Latest R410a products up to size 900 or 101kw nominal cooling.

PUMY is baby heat pump VRF.
It is small outdoor unit 3ph or 1 ph & uses all the same indoor units available for the larger City Multi systems.
Ideal for domestic applications.

[Yuri B.]

Thank you Thermatech for your sharing knowledge.

PUHY-P...-THMU-A is for 230/60
PUHY-P...-YHMU-A is for 460/60

Both types' models thus designated have cooling capacities 72,96, and 120 Btu/h.

When model's cooling capacity exeeds 120 Btu/h, then there between T and H/Y and H appears "S" ? What it stands for ?

[Thermatech]

P = packaged air conditioner
U = heat source is air
H = Series is Y series or R = R2 heat recovery
Y = Veriable capacity inverter

P = Refrigerant R407c or R410a
250 = model size

The last model reference letters refer to the voltage & development model

You will need to ask Mitsubishi Electric agent in your country for detailed explanation for the last letters as they are completely different to what we have in the uk.

[Yuri B.]

About this 4-way valve
When not powered:
Conducts electricity between the oil separator outlet and heat exchanger, and between the gas ball valve (BV1) and the accumulator
to complete the circuit for the cooling cycle.
When powered:
The electricity runs between the oil separator and the gas ball valve, and between the heat exchanger and the accumulator.

This circulation is for heating.

[Yuri B.]

The above from a service handbook on Mitsi. Evidently the translator from Japanese knows nothing - neither about electricity nor refrigeration.

[Yuri B.]

Many thanks to Thermatech and Narkom.

The original info for my task turned wrong - the unworking PUHY was from a different system and related to a different site.

[jamespin]

anyone know error code 4230 and the cause problem

[moondawn]

hi there on my list of city multi fault codes i have down
In My PUHY book which is for R410a so not exactly the model number for yours

• 4230 radiator panel overheat protection

Says the heat sink temp is above 105 degrees c

Could Be Faulty FAN BOARD FAILURE
OUTDOOR UNIT FAN FAILURE
AIR PASSAGE BLOCKAGE
THHS FAILURE
cheers lee