MCi Crusader II 1989 Maintenance Manual page 473

Date 1-1-89,
Page -__ ,_
5 -_ 3 _ _
MC-9 MAINTENANCE MANUAL
If the heating system is to be drained without draining the
engine cooling system, close gate valves in engine com-
partment and drain radiator cores. A manual vent plug is
provided in the top of the main heater core and at the top of
the driver's heater core for bleeding air while refilling. The
vent plugs allow air to enter during draining.
OPERATION
Controls for coach heating system are located at the
driver's switch panel. The temperature control selects the
temperature range desired and the system automatically
maintains the pre-set limits. Blower motors for coach heat-
ing, driver's heater and defroster are controlled by switches
on the driver's switch panel.
MAIN HEATER WATER VALVE
(ELECTRICALLY .ACTUATED)
Figure 16-2A. Electrically Actuated Main Heater Water Valve
Used Prior To Unit 39263.
Prior to unit 41089, the flow of hot water to the main heater
core is controlled by an electric water valve mounted in the
right front baggage compartment
Valves from two different manufacturers are present on the
coach el:> built prior to unit 41089. One make was used prior
to
unit 39263 and another was used from unit 39263 through unit
41088. These two valves are interchangeable as complete
assemblies. Refer to TMC/MCI Service Bulletin No. 2224 for
information on replacing the earlier valve with the later vaive.
NOTE: The following information applies
specifically to the earlier valve but is
generally applicable to the later one.
The valve is designed so that the pilot valve within the
.1ssembly opens and closes a port which directs pressure to
either the top or bottom of the valve diaphragm, thus opening
or closing the valve.
A delay action is built into the water valve through the means
of an orifice in the valve body and a modulating cup on the
diaphragm assembly. When the coach is operating with no
current to the water valve solenoid, intet water pressure is
directed to the upper side of the diaphragm, thus forcing it open.
The pilot valve is normally open, relieving any build-up of
pressure under the diaphragm. When the solenoid is energized
the pilot valve closes, water pressure builds up through the
orifice to the underside of the diaphragm and keeps the valve in
closed position.
Figure 16-28. Electrically Actuated Main Heater Water Valve
Used On Units 39263 Through 41088.
MAINTENANCE
The main heater water valve requires a minimum amount of
maintenance. The valve should be free of any sediment or dirt
which might interfere with its operation. The diaphragm (8)
(figure 16-2C) should be replaced every year before the heat-
ing season begins. No other maintenance is needed unless a
malf4nction occurs.
OVERHAUL
In the event of a malfunction. remove the water valve from
the system.
CAUTION: Do not allow any liquid to
reach the solenoid coil. After removing the
valve from the system, carefully drain the
remaining liquid from the inlet and outlet
openings.
DISASSEMBLY
Refer to figure 16-2C.
Remove the terminal nuts, lockwashers. and washers from
the valve.
Remove the screw (17) and lockwasher (16) from the coil
and container assembly (1).
Remove the valve seat assembly (3) from the coil and con-
tainer assembly (1) by turning it counterclockwise with a
wrench.