Although CalCERTS is not in the position to give directions or technical advice to licensed installers, I will list a few observations that you may want to consider:
- Adding refrigerant typically lowers superheat and raises subcool, but this depends on other factors as well, so caution is advised not to overcharge. When an initial charge is substantially off, these reactions are sometimes non-typical.
- An improperly mounted TXV sensing bulb will affect superheat - see Mfr's instructions for proper location, angle/placement, and mounting bracket requirements.
- A TXV sensing bulb must be properly insulated to Mfr's specs.
- A blocked TXV - such as debris from brazing - will affect operation.
- Presence of non-condensables, such as air in the lineset caused by improper evacuation and vacuum, can cause a "mushy" reaction in the Superheat numbers.
- Verify that the digital manifold gauge and measurement probes are in calibration and that there is good clean contact at the temperature points of contact. The contact points must be free of oil and corrosion and have a solid mounting surface.
- Verify that the manifold gauges are connected properly to the correct linesets and service ports.
There are other factors to consider, so it is advised that the installer reach out to his/her Technical Support contact either at the distributor level or the Manufacturer level.