Service manual

8
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.
3) If the resistance between any two terminals is
infinity, the winding is open.
On a good compressor, the highest resistance will be between
the R (run) and S (start) terminals. The lowest resistance will
be between the C (common) and R (run) terminals. The
intermediate resistance will be between the C (common) and
S (start) terminals. Notice that compressors have the
identification of the terminals marked on either the terminal
cover or on the compressor housing.
7. Overload Switch
Mounted on the outside of the compressor housing is a two
terminal overload switch. Note: We have a few models with
internal overloads that are non-serviceable. The switch is
connected in series with the common terminal, so 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.
8. 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 end is mounted an axial
flow or propellor type fan which circulates outdoor air
through the condenser coil.
* Some models use a squirrel cage on both ends of the motor.
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:
9. 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
the fan capacitor or a white wire in a wire
nut then the white wire connects through
the disconnect plug to the thermostat.
c) The brown wires from the motor connect to
the fan capacitor.
2. To check the motor winding resistance carefully,
check the resistance between each of the wires and
ground (preferably a copper refrigerant tube for a
good connection). These readings must be infinity.
Any continuity means the windings are grounded.
If there is a reading of 0 between any two leads, the
motor is shorted and is no good. If there is a reading
of infinity (no meter reading at all) between any two
leads, the winding is open and the motor is no good.
Note: A motor with 2 brown leads will have an
O reading between 1 brown wire and either
the black or white wire.