Hi All ,

Got called out to a reverse cycle ducted Daiken RZQ71KCV4A AC unit today not cooling or heating !

Switched it to cooling and checked air temps at outlets , pumping out around 27 C , near enough the same temp at the intake filter , checked and cleaned filter , replaced .

Went to outdoor unit checked / cleaned then tested all the intake , coil , discharge etc thermisters reading about 20k ohms , checked low pressure and high pressure switch for continuity all good . Checked windings in the compressor all good . Capacitors all good !

Put on my gauges after unit was running about 10 mins and seen that discharge was 890 kpa / 6 c and the outlet line was 15 c with clamp on thermometer . Suction was 800 kpa / 3 c and 30 on the line .

So at first I thought the reverse valve might not be seating properly and cross flowing due to suction / discharge pressures being so similar so checked temp differential across inlets / outlets and same temps noted !

So I always thought the suction line should be about 5-6 c and not 30 c . What temp should I look for normally on the superheat in C ?

If it was low on refrigerant surely the discharge would still be a lot higher after it has went through the condenser then out on the liquid line at the 2 way valve ? Weird thing was the liquid line was sweating leaving the unit going to the Evaporator then coming back at 30 C.

Could it simply be low on gas or is it more sinister like a faulty expansion valve or solenoid stuck open ?

please help a rookie out !