A system that short cycles, overshoots, or insists the room is twenty degrees when it plainly is not usually has a sensor or a wiring fault rather than a refrigerant one.
We verify the return-air and coil sensors against a calibrated probe, check the control wiring end to end, and confirm the board is actually receiving the call it thinks it is.
Where a smart or zoned control has been added to older equipment, we check the two are genuinely compatible rather than merely connected.
