Holiday Navigator 2003 Owner's Manual page 376

Electrical Systems - Chassis
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Safety and Handling of 134A and Pag Oil:
• When working with any refrigerant system wear eye protection
and hand protection.
• Pag Oil irritates the skin. Flush with water immediately if in
contact with any body part.
• Ensure any service work performed on the A/C system is in a well
ventilated work area.
• Keep open flame away from service area. The discharge of a
refrigerant gas near an open flame can produce a very poisonous gas.
NOTE: O-rings used in a 134A system are Hydrogenated Nitrile
Butadiene Rubber (HNBR). These are green in color and required
for the 134A system.
A/C Heater:
The A/C system will also produce heat to warm 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 flow through the heater core. The heater core is tubing and fins. 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 flows through the heater core. When the temperature is in the COOL
position coolant flow bypasses the heater core. In either position the air flow is
felt at the discharge vents.
Diagnosis of Electric Water Valve:
Theory of Operation: The thermostat is a potentiometer. The water valve,
which controls the water flow to the heater core, is opened and closed by a
stepper motor mounted on the water valve. A control module compares the
output voltage from the potentiometer 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 potentiometer 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.
• The 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.
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