Mick13
26-05-2012, 12:02 AM
Hey guys, came across and interesting one yesterday, Daikin RZP125DV1 (R407c), client reported that unit had been going out on fault code U0 "refrigerant shortage". I put my guages on the system, its winter here so i ran the unit on heating, comnpressor started up, ran for about 10 seconds and pulled the suction pressure down to about 350-400kpa, and compressor cuts out, with the red lights on the outdoor PCB lighting up "protective devices activated".
After watching this repeat itself 3-4 times, i took the suction transducer off and put it on a bottle of R22 i had (similar pressures). After i did this, the compressor started up and didnt cut out, but pulled the suction pressure down to about 30kpa and sat just above zero for a couple of minutes with ice going from my outdoor expansion valve to the outdoor coil, then the pressure slowly came back up to roughly normal pressures and then ran for roughly 30 mins and seemed to be running well, and pumping out heat inside.
I put the transducer back on the unit, and now it had warmed up inside quite alot so i put the unit on cooling, and although the compressor didnt ramp up much (it was a cold morning) it seemed to be running ok.
I put it back on heating mode, and straight back to the original problem, ran for 10 seconds, suction down to about 350-400kpa and cut out.
I put the transducer back on the bottle again and the symptoms repeated, it pulled down to about 30kpa, ran for a couple of minutes then came back up to normal running pressures and started to run well.
Now im leaning towards something to do with the outdoor expansion valve, the liquid line before the valve was warm/slightly above ambient, but the fact that it seems to come good after a while makes me think it may be PCB related, or possibly some sort of sensor fault that controls the valve, what do u guys think?
im very open to ideas.... thanks in advance
oh another thing, from my experience with daikins & EEV's, im led to believe when the power is cut to the unit and turned back on, I should hear the EEV ticking as it opens fully, im not 100% if that applies to this model but when i reset the power i dont hear anything....
After watching this repeat itself 3-4 times, i took the suction transducer off and put it on a bottle of R22 i had (similar pressures). After i did this, the compressor started up and didnt cut out, but pulled the suction pressure down to about 30kpa and sat just above zero for a couple of minutes with ice going from my outdoor expansion valve to the outdoor coil, then the pressure slowly came back up to roughly normal pressures and then ran for roughly 30 mins and seemed to be running well, and pumping out heat inside.
I put the transducer back on the unit, and now it had warmed up inside quite alot so i put the unit on cooling, and although the compressor didnt ramp up much (it was a cold morning) it seemed to be running ok.
I put it back on heating mode, and straight back to the original problem, ran for 10 seconds, suction down to about 350-400kpa and cut out.
I put the transducer back on the bottle again and the symptoms repeated, it pulled down to about 30kpa, ran for a couple of minutes then came back up to normal running pressures and started to run well.
Now im leaning towards something to do with the outdoor expansion valve, the liquid line before the valve was warm/slightly above ambient, but the fact that it seems to come good after a while makes me think it may be PCB related, or possibly some sort of sensor fault that controls the valve, what do u guys think?
im very open to ideas.... thanks in advance
oh another thing, from my experience with daikins & EEV's, im led to believe when the power is cut to the unit and turned back on, I should hear the EEV ticking as it opens fully, im not 100% if that applies to this model but when i reset the power i dont hear anything....