Mitsubishi PURY-P200 YMF-C

[woody100]

Hello,

I have a Mitsubishi PURY-P200 YMF-C with 3 fan coils attached, each with its own remote controller and a G 50a which only seems to be used for monitoring. The problem we are experiencing is in heating the head pressure is 300psi (on 407c) and the system eventually trips on high compressor shell temperature TH10 and does so every few hours. We have measured the temperature and it is rising to the cut out set point. We have removed the refrigerant and weighed it back in and then checked refrigerant level via the sub cooling and superheat as advised in the manual and all is in order. The condensing unit has no expansion device for the outdoor coils when in heating so i am assuming that the refrigerant is expanded in the BC box prior to reaching the distributor and then the outdoor coils.
The only thing i didn't record was superheat reaching the compressor in heating mode.

can anyone help?

[install monkey]

check,air filters,evap coil clean,indoor coil thermistors should speed up the indoor fan as the coil temp rises, put the local remote usually par f27 in test heat and check the coil temp rises to 33 deg, proving the bc box is operating,also them units the indoor lev's have a tendancy to fracture and u find the lev head loose inside the unit,thus not operating

[woody100]

Thanks for your reply. The indoor units are GUF100RD, initially the box filters inside the units were dirty (no pre filters) but these were cleaned a well as we could on site and it did make a difference to the air flow within the room but little difference to the discharge pressure. Didn't realise the fan was suppposed to speed up on coil temp, i thought it responded to room temp, i shall check that next time i'm there. In heating which LEVs expand the refrigerant prior to the outdoor coil?

[install monkey]

check you e mail

[Thermatech]

The LEV for heating mode is LEV3 at BC box.
The warm liquid return from the indoor units in heating to the BC & through the tube in tube subcooler circuit then through LEV 3 & flashed off into suction pipe to outdoor unit.
If the compressor is overheating its normally due to poor suction pressure & not enough cooling to the comp motor windings.
Prime suspect BC LEV 3 failed at small opening possition but could also be anything other system problem which causes low suction pressure.

[woody100]

Thanks for all replies

[install monkey]

did u get the email woody

[woody100]

Yes thanks very helpful