The valve will operate normally with a lower pressure differencial. At 225 psig head and a 60 psig suction it will close off, pump down like normal to 30 psig, compressor shuts off on low pressure control, and the valve does not leak by. But At 275/60 psig it stays wide open with no power to the coil. Even pulled the coil off the stem to be sure. Stays wide open and the only way to shut off the compressor is the main breaker, or closing the king valve. Like spaceman said, it makes no sence.
The arrow on the valve is pointed to the TXV, it is in the right way. Don't know what caused the original failure, but this problem is on my short list. It is like 200 PSI Diff is the maximum it can close against, but that seems like a normal application demand of a LLSV. Maybe a flow thing? To much liquid velocity? 15 ton compressor, 27 Lb charge, R-22, through a 7/8 liquid line. It all seems like the right fit, but two valves doing the same thing at the same point, makes one wonder.
The MOPD of the valve is the pressure that, when exceeded, the electro-magnetic force generated by the coil when energized is insufficient to pull the valve's plunger up to the top of the enclosing tube.
The MOPD has nothing to do with whether the valve will close or not.
Barring a mechanical or contaminated problem, solenoid valve failure to close is commonly caused by an oversized valve. Oversizing results in too little pressure differential across the valve port....the pressure on top of the disc must be a minimum 1/2 lb greater than the pressure below the disc or the valve will be in danger of not closing.
Solenoid valves should be selected based upon capacity, not line size.