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20 08 CONTESSA
ELECTRICAL SYSTEMS - CHASSIS — 9
Select this position when maximum cold air is
desired or to keep outside air from entering the
motorhome.
Heat and Defrost Operation:
Set the Mode Control Switch to the
desired position.
Set the Temperature Control Switch to
the red zone.
Operating Tips & Hints
Air intake and discharge temperatures are
greatly affected by ambient temperatures and
relative humidity. A large amount of cooling
capacity is used to dehumidify as well as
cool air. After three to ve minutes of A/C
operations, discharged air temperature should be
approximately 20º - 30º F cooler than the fresh
or recirculated air entering the A/C system.
Winter Use:
De-ice the windshield using the
DEFROST mode.
Air will heat up faster with a slower
blower speed until normal operating
temperature ranges are reached.
Summer Use:
Close all windows and vents to hot,
humid outside air.
The recirculation blower provides quick
cool down.
Use a lower blower speed to produce
cooler air.
Heater:
The heater warms the air in the dash area.
Much like the refrigeration side of the system, a
liquid will be used in the process. This liquid is
the engine coolant. The coolant is passed from
the radiator to an electronic water valve. The
water valve, when open, will allow the coolant
to ow through the heater core. The heater core
is much like a miniature radiator. Air is drawn
into the system by a blower motor through the
outside recirculation door opening.
Air is blown through the A/C evaporator core
and then through the heater core. When the
temperature control is in the WARM position
coolant ows through the heater core. When the
temperature is in the COOL position coolant
ow bypasses the heater core. In either position,
the airow is felt at the discharge vents.
Electric Water Valve:
The water valve controls the water ow to
the heater core. A control module compares
the output voltage from the thermostat to the
feedback for the stepper motor of the water
valve. The control module then drives the
motor to within one-half volt of the control
thermostat voltage.
Functional Test:
Start and operate the engine until
the water reaches normal operating
temperature.
Set the HVAC temperature control to the
full hot position.
Discharge air outlets should have hot air.
Rotate the temperature control to full
cold position.
Allow 10 minutes for the temperature
to stabilize.
The discharge air outlets should have
cold air.
System Components
Compressor - The compressor is
belt driven from the engine through
the compressor and electronic clutch
pulley. The compressor will pump
freon from a low-pressure gas into a
high-pressure, high-temperature gas.
This is the start of the refrigeration
process.
Condenser - The condenser is made
of coils and ns which provide rapid
transfer of heat from the refrigerant
as external air passes over the coils.
The high-pressure gas is changed to a
high-pressure liquid.
Condenser Fan - A steady ow of
cooling air is maintained across the
condenser during system operations.
Expansion Valve - The expansion
valve suppresses the refrigerant into
the evaporator according to the cooling
requirements. The pressure is reduced
in the restrictive effort of the expansion
valve. A part of the valve is the
capillary tube assembly. The capillary
tube is the sensing bulb at the outlet of
the evaporator.
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