MCi Crusader II 1989 Maintenance Manual page 479

Date
1-1-89
Page __
1_e_-9 _ _ _
MC-9 MAINTENANCE MANUAL
Another cause of inadequate cooling is a dirt-clogged
evaporator coil or filter. Dirt acts as insulation and is also a
restriction to air flow.
The refrigeration load -is not constant and is affected by
outside temperature, relative humidity, passenger load, the
number of stops. 1:1.tc. The compressor will load or unload
depending on such operating conditions. The following
information on the operating conditions is approximate and
will vary:
Oil Level in compressor ................. 1 h of sight glass
Freon Level in receiver ................. ½ of lower glass
Speed of engine - fast idle .. : ................... 900 rpm
MANUAL SWITCH CONTROLS
Temperature Rheostat - Located on panel to the left of the
driver. it controls the air temperature in the coach during
both heating and air conditioning.·
Passenger A/C Coach Heat- Located on the switch panel
to the left of the driver. In "A/C" position, the air condition-
ing system is energized and functions as required. In the
"Off" position, the conde~ser and evaporator fans are shut
off. In the "heating" position, the evaporator fans are at
operating speed and the air conditioning compressor is
unloaded.
FAST IDLE
The fast engine idle can only be used to power the air
;onditioning system when the coach is stationary and the
emergency parking brakes are applied. The feature con-
sists of a fast idle switch on the driver's switch panel, an air
valve in the engine compartment and an air cylinder
mounted on the engine governor.
Placing the Fast Idle switch ON energizes the air valve
which lets air pressure to the air cylinder, causing the
governor-operating lever to be moved to the fast idle posi-
tion. To eliminate the possibility of engine damage, the
accelerator cannot be operated when the fast idle switch is
closed.
DAILY CHECKS
1. Check oil level in compressor.
CAUTION:
It
is essential that only the cor•
rect lubricant be used, such as Texaco WF
68, WFI 132, or equivalent.
2. Check Freon level in receiver.
3. Check and clean condenser coil. Do not use caustic
soap.
4. Check and clean filter.
5. Check compressor and belts.
TEST EQUIPMENT
Specific air conditioning test equipment is recommended·
for routine servicing of the air conditioning system. It
includes the following:
Qty. Part No.
1 16C-2-92
1 16C-2-93
16C-2-94
Description
Air Conditioning Test Equipment Kit
Halide Leak Detector (Bemz-o-Matic
Model TX-12)
Freon 12, 35 lb. tank (15.9 kg)
3
16C-2-95
16C-2-96
Charging Hoses - (Yellow Jacket
Hoses) (HCL-36)
Pressure Gauge 0-400 lbs. with
R 12 Temperature Scales
Compound Gauge 0-30" Vac. 0-150
lbs. with R 12 Temperature Scales
Gauge Manifold with handwheels
Thermometer - (Mechanical) to
check Superheat 10° to +100°F
The above parts a re available from Universal Coach Parts
Inc .. Northlake, Illinois and in Canada from Motor Coach
16C-2-97
16C-2-98
16C-2-99.
Industries, Service Parts Division.
A/C SYSTEM MAINTENANCE PROCEDURES
AIR CONDITIONING SYSTEM SOLENOID VALVE
When the Passenger A/C-Heat control is switched on, the
system solenoid valve is actuated and allows refrigerant to
circulate within the air conditioning system. Turning the
switch off
will
close the valve. This valve is located in the
condenser compartment.
The valve can be opened or closed manually in case the
solenoid's electric operation of driver's switch operation is
suspect. Removal of a seal cap on the valve will expose a
3/16" square stem. To manually open the valve, place a
wrench on the stem and turn it 180 degrees(½ turn) coun-
terclockwise.
CAUTION: Turn only 180° counterclock-
wise. Do not backseat.
To manually close the valve. turn the stem½ turn clock-
wise until the stem is tight {seated).
NOTE: The manual stem must be in the
closed position before automatic solenoid
operation will take place.
PUMPING DOWN
Whenever it is necessary to "open" the refrigeration sys-
tem for service or repa,irs, the refrigerant must be removed
from that part of the system requiring service. Localizing
refrigerant into one part of the system (usually the receiver) .
is known as "pumping down." The procedure is as follows:
1. Close the outlet valve on the receiver. backseat the
suction valve, install a gauge and turn the valve forward
¼
turn, thus enabling visual check of the suction pressure.
2. Connect a jumper wire between horizontal studs 1 and
2 in remote control box
NOTE: This jumper will allow the com-
pressor clutch to remain engaged after
pressure drops below 15 psi (103.5 kPa).
3. Start the engine and operate the compressor until
pressure reads 1-2 psi (6.9-13.8 kPa), then disconnect the
jumper wire.
4. The pressure will probably rise. Install jumper wire
again and lower the pressure until it remains at 1 or 2 psi
(6.9-13.8 kPa). Close inlet valve to receiver tank. Stop
compressor.