PURY-P650YGM-A - Defrost

[AbsoluteWDJ]

Been to site today and connected M-net tool on a PURY-P650YGM-A. When I went to outdoor unit the coil was a block of ice. I forced defrost and also monitored defrost with 50 minutes elaspes. Every defrost i witnessed lasted about two minutes and TH5 never reached 20c (which i set) hence why the coil is frozen. Has anyone else experienced this. Mitsi tech had a 20 minute wait and was a Friday afternoon!

[marc5180]

Did you measure the resistance of TH5 & TH7
Maybe the sensor is out of calibration.

Also is the refrigerant charge ok?

The outdoor unit monitors the TH7 coil temp sensor & after 50 mins if its below -8 deg C then it will start deforst.
Then during defost it monitors TH5 coil temp & discharge pressure.
If the discharge pressure is >10bar & TH5 is > +8 deg C after 4 mins of defrost then defrost will be complete.

So important to confirm the TH7 & TH5 temp sensor data is correct.
For instance if the TH7 has failed or reading incorrect temp & is always reading higher than -8 deg C the outdoor unit will not ever start a defrost.
If TH5 is reading a few deg C high then the unit might do 4 mins defrost only & finish defrost because TH5 reports +8 deg C but the coil has not completely defrosted & the actual temp at TH5 is still lower than +8.


Check hot gas flow during defrost to ensure no incorrect bypass to suction & correct gas flow through the check valve block & solenoid valve block through into the outdoor coil, especially SV1,SV2 & SV3