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3) Voltage
The voltage (electrical pressure) at the unit should be 115
volts (domestic USA) and all electrical components will
perform best at the correct voltage. However, the voltage will
vary and the air conditioning system will perform
satisfactorily within plus or minus 10% of the rated (115)
voltage (domestic USA). Therefore, the voltage has to be
between 103.5 volts and 126.5 volts.
2. Power Supply - Generated By On-board Motor
Generator
If the power supply for the recreational vehicle is supplied by
an on-board motor generator, its wiring may be identical to
the commercial power described above.
There are, however, some motor generators on which both the
current carrying leads are insulated from the ground. That is
to say; there is no grounded neutral, so there will be 115 volts
(domestic USA) between the black and white leads, but there
will be 0 volts between either lead and ground.
WARNING: The service technician must keep in mind
when checking to make sure that the power is turned off –
check only between the hot (black) lead and the neutral
(white) lead. The black lead could still be hot even though
there is 0 volts between it and ground.
3. Compressor Motor
The compressor motor is located inside the hermetic
compressor housing and is therefore, not accessible for
service or visual observation in the field. However, the motor
winding condition can be analyzed by using an ohm meter.
Be sure to remove all the leads from the compressor terminals
before making this check.
1. If the resistance between any two terminals
is 0 ohms, the motor windings are shorted.
2. If the resistance between any terminal and
the compressor housing is anything but
infinity, the winding is grounded.
4. Overload Switch
Mounted on the outside of the compressor housing is a two
terminal Overload switch. The switch is connected in series
with the common terminal. If the switch opens, it will cut the
power to the compressor motor. The switch will open as the
result of either or both of two conditions that could be
harmful to the compressor.
1) High Amperes (Current)
The switch contains a heater which
increases in temperature as the current
increases. The higher temperature warps
the switch and will cause it to open before
the windings reach a dangerous
temperature.
2) High Temperature (Thermal)
The switch is clamped tightly against the
compressor housing and located close to the
windings. Therefore, as the windings reach
a higher temperature, it takes less current to
cause the switch to open.
As can be seen, the switch is always affected by a
combination of current to the compressor and winding
temperature.
5. Fan Motor
The air conditioning unit has one double end shaft fan motor.
On one shaft end is mounted a centrifugal or squirrel cage
blower which draws air (return air) out of the recreational
vehicle and blows the conditioned air down into the
recreational vehicle. On the other shaft end is mounted an
axial flow or propellor type fan which circulates outdoor air
through the condenser coil.
An important step in installing a replacement fan motor is to
check the direction of rotation before it is installed. On all
models, the condenser fan pulls the air through the coil.
Fan Motor Check Procedure
If a fan motor refuses to perform properly, it can be checked
in the following manner:
1. Be sure the motor leads are connected to the proper
points –
a) The black wire from the motor connects to a
black wire inside a wire nut then the black
wire connects through the disconnect plug
to the selector switch. The red wire from
the motor connects to a red wire in a wire
nut then the red wire connects through the
disconnect plug to the selector switch.
b) The white wire from the motor connects to
a white wire in a wire nut then the white
wire connects through the disconnect plug
to the thermostat.
