Air conditioners lately come with power cords with the hot wire with a shield, the neutral a separate shield, and no shield on the ground wire. These shields are not grounded, but are meant to sense if a grounded metal object (like the AC unit's metal case) cuts into the cord. The sensor is in the power plug. I've salvaged these cords off AC units people have tossed.

I take off the power plug, and using a regular 3 prong power plug, tie the shield drain wires to the ground wire and the ground pin. This should act like an RF shield to confine RFI in the hot and neutrals, or keep RFI out of these wires. This should help more if your house uses BX housewire or conduit (which should also act like shielding)
This might be useful to keep your RF from getting into the rig's power supply. Or keep the switching power supply crud from leaking out to your antenna.