Went on a service call yesterday. Found a 13 SEER outdoor unit, hooked to an 8 SEER indoor coil that still had the original piston in it (a 1987 carrier coil). The outdoor unit was installed 4 years ago, the compressor was replaced last summer, they didn't get all the bolts back in.
Checked pressures, it was almost empty of refrigerant, then checked further and found lots of surprises. One pic I missed getting was from the furnace that had the blower motor run cap taped to the wires going to the blower motor.
But looks like I'll be installing a entire new system (furnace, coil and new outdoor unit) next week.