Safety And Handling Of 134A And Pag Oil; A/C Heater; Diagnosis Of Electric Water Valve - Monaco DIPLOMAT 2004 Owner's Manual

DIPLOMAT 2004
9 •348

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.
ELECTRICAL SYSTEMS - CHASSIS