Question:
My Fedders window air conditioner buzzes and the lights dim, it does this
about 3 times before it will kick in. Do I need a larger amp breaker?
Answer:
The motor cannot start the compressor. The noise is made by the stalled
motor attempting to start. When the motor overload pretection (in the
motor, probably) overheats, it stops the motor. When it cools again, the
motor restarts. It seems to be taking three tries for enough time to elapse
for the coolant pressure to bleed off so that the motor can start the
compressor.
Whatever it is, if the breaker isn't tripping, it isn't the breaker.
The a/c will normally overload the circuit when starting, but for only one
or two seconds. The problem could be the size of the wiring or the amount
of other load on the circuit. If the lights that are dimming are on the
same circuit, the circuit might be overloaded. If they are on another
circuit, the voltage at the panel is sagging. If you can, check the voltage
at the same outlet the a/c plugs into with no load on the circuit, then
again with a heavy load, like a 1500-watt hair dryer. The difference should
be no more than around five percent or so. (The usual recommendation is
five percent at the full load current of the circuit, which would be 2400w
for a 20-amp circuit, or 1800w for a 15-amp circuit. However many household
circuits don't measure up to the recommendation. If the unit starts at all,
the problem is probably not voltage sag, anyhow.)
More likely, the compressor is overloading the motor when starting. This can
be caused by restarting too soon after stopping. The motor that drives the
compressor will not start nearly as big a load as it will run, so starting
depends on the internal pressure being low so the compressor presents a
light load at startup. It takes a few minutes (five or so) for the pressure
to bleed off before the unit will start again after operating. The time it
takes for the three start attempts may tanke enough time for the pressure
to come down far enough that the motor will start.
The unit can also become hard-starting through failure, but since I know
nothing about fixing an air conditioner
