I got called to a domestic Daikin Heatpump and found that the compressor had seized and that the unit displayed a E6 error. I replaced the compressor and charged it up with R22. After weighing in the R22 the return gas pressure stood at 120psi! I then noticed that the small filter drier in the suction line was icing up from the drier to the compressor. I think refrigerant is backing up in the return line causing the 120psi pressure and im getting a huge pressure drop across drier.I cannot check the pressure at the compressor as there is no access. I work mostly on commercial systems and would like to know whether this is a common fault? The system is only 2 years old?