Climate & waterShows up, but not every week
Window air conditioner
Also called room AC, window unit.
A run capacitor, two fan motors, a contactor, and a refrigerant loop you do not vent. The capacitor is the salvage people actually want.
A donor is the dead machine. The parts below are what is still worth removing from it. “Leave it” is a part that is physically in there and should stay in there: too dangerous, too worn, or only useful as part of a repair you are not doing.
A scrapped machine is a box of parts that failed at different times. The reason it was thrown out is often one bad piece. The motor, the cord, the supply, and the screws are frequently still good. This index says which is which.
Why it is in the trash while the parts are not
A dead capacitor, a dead fan, or it leaked. A failed run capacitor is the most fixable and the most useful part.
Before you open it
Do this while it is still unplugged, cool, and not leaking. Unplug. Discharge the run capacitor. It is mains-rated and it holds a charge. Do not cut the compressor lines.
Where the dead machine usually is
- Bulk trash day — Curb
- Remodel and construction dumpster — Curb
- Garage and shed — In the house
Heavy and full of refrigerant. Same rule as a fridge.
How it comes apart
Side cover. The capacitor is a metal can, clearly marked in µF.
Tools: Nut driver, Meter, Discharge resistor.
Words on this page
- mains
- Ordinary household wall power. It can kill. Unplug before you open anything that used it, and do not experiment on live wiring.
- capacitor
- A part that stores a small amount of electrical energy. Large ones in power supplies can stay charged after you unplug. Discharge them before you touch the leads.
What to take
The table is the short version. The notes under it describe that part inside this machine, not only the general description.
| Part | Call | How many | How often | Where to look |
|---|---|---|---|---|
| Film capacitor | Prize | 1 | always | Side compartment. |
| Single-phase induction motor | Worth pulling | 2 | usually | Blower and condenser fan. |
| Power relay / contactor | Worth pulling | 1 | usually | Contactor or relay. |
| NTC thermistor | Bonus | 1 | sometimes | Room sensor. |
| Bimetal thermostat | Bonus | 1 | sometimes | Older mechanical thermostats. |
| Panel switch | Bonus | 1 | usually | The control. |
Prize
Dual run capacitor, values printed, 370 or 440 VAC.
Side compartment.
Discharge, then read the print. Replace with the same µF if you are repairing. Keep it if it measures right.
Failure is common and obvious: bulged or far off value.
Worth pulling
PSC motors that need that capacitor.
Blower and condenser fan.
Label which wires were on which capacitor terminal.
Good if the original fault was the cap.
Switches the compressor.
Contactor or relay.
Read the coil voltage, often 24 VAC or mains.
Pitted contacts if the unit short-cycled.
Bonus
A bead on a lead.
Room sensor.
Calibrate.
Good.
A knob and a switch.
Older mechanical thermostats.
Crude.
Good.
Fan speeds.
The control.
Map it.
Good.