Picked up keys from 707 N 2nd St. Unit C: Goodman 2123: I found electric furnace with bad transformer. I tested controls and wiring for shorts and found none. Also found evaporator coil very dirty. System running without a filter. I tested for shorted and grounded controls and wiring. Found none. I replaced transformer with fuse. Check control circuit amps for cooling and heating modes: 0.45 A. I clean evaporator. Replaced air filter. Unit D: checked to see if heat is operational. Found heat was working and set at 58. Dropped off keys at 4564 Chouteau.