Monaco SIGNATURE 2001 series, Owner'S Manual

Page: 248 / 327

Diagnosis of Electric Water Valve:
Theory of Operation: Monaco models
with a center dial temperature control use a potentiometer at the control head
for input of desired temperature. 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 con-
trol to that of the feedback for the stepper motor of water valve. The control
module then drives the motor to within one-half volt of the control poten-
tiometer voltage.
Functional Test:
• Start and operate the engine until the water reaches
normal operating temperature.
• Set the HVAC temperature control to the full hot posi-
tion.
• 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 cool air.
No Heat:
• Check the blower and air mode operations. Fix or
repair prior to proceeding.
• Verify the engine has obtained normal operating tem-
perature. (Check with engine manufacturer for the
proper procedure.)
• Check the temperature of the inlet hose at the water
valve. The inlet water hose temperature should be
approximately the same temperature as the engine
water temp.
• With the temp control on set to the full hot position,
check the outlet hose of the water valve. The outlet
hose should be the same temperature as the inlet
hose.
Vacuum Generator:
The air plenum box contains the heater core, the air
conditioning evaporator and internal doors which direct the air flow. The
doors are controlled by vacuum operated dash pots. The vacuum generator
uses compressed air from the front air tank to oscillate a diaphragm creating
vacuum creating approximately 15 inches of vacuum. The vacuum is then
stored in a reservoir. The vent control knob applies or removes vacuum to the
dash pots opening or closing the doors. The vacuum generator will operate
when the ignition is ON and the system is operating.
Electrical Systems - Chassis
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