Hi Guys

New to this forum so be gentle , I got a call out to a tripped out ahu with one coil with 2 circuits and separate condensers ( Airedale ) . They both have txv's, and are brought in in stages of demand. One had a leak which was fairly obvious (circuit 2) and has been repaired . I weighed out both circuits to get an idea of roughly correct weights as no documentation on site. One had 16kg (407c) the other had 6kg. I ran up circuit 1 today after recharging with the reclaimed 16kg of refrigerant and noticed after about 5-10 mins of operation that the coil started to freeze up , now the service valves on this unit are a bit limited to say the least , I have one on the discharge leaving compressor before condenser and one on the suction again on the side of the compressor, that's it. So on the basis of coil freezing I understand that airflow may be the problem , but also possibly undercharge , how will I determine correct subcooling / superheat when service valves are where they are ? I have checked superheat at condenser and am getting 15 k , but how to check subcooling if service valve is before condenser ?