The principles of operation of these functions are
OPERATING CONTROLS
described separately. Each of the descriptions is written
The operating controls are mounted on the control
with the assumption that the engine is operating and
panel (fig. 11-20). The thermostats, pressure controls,
functioning normally.
and switches are mounted inside the housing near the
Cool Mode (Air Conditioning)
devices they control. The functions of the controls and
indicators are listed in table 11-3.
Moving the selector switch to the AIR CON-
DITION position starts the refrigeration cycle. As you
MODES OF OPERATION
learned earlier, the refrigeration cycle is based upon the
The air-conditioner can ventilate, cool, or
principle that liquid refrigerant becomes cold as its
dehumidify the area to be conditioned, as determined
pressure is reduced, absorbs heat as it expands to a
by the setting of the selector switch. (See figure 11-20.)
vapor, becomes a warm gas when compressed, and
Table 11-3.--A/M32C-17 Controls and Indicators
Nomenclature
Function/Indication
Normal Position
Range/Setting
1. Outlet air temperature
Indicates outlet air temperature
As desired
2. Clutch indicator light
Light ON indicates clutch en-
ON-OFF
gaged
3. Outlet air pressure
Indicates outlet air pressure
1 to 4.5 psi
4. Compressor suction pres- Indicates compressor suction
48 to 65 psi
sure
5. Compressor discharge pres- Indicates compressor head pres-
100 to 365 psi
sure
sure
6. Panel light switch
Illuminates control panel
ON-OFF
7. Fuel level gauge
Indicates fuel level in large tank
FULL to EMPTY
8. Fuel warning light
Indicates large fuel tank is empty;
ON-OFF
small fuel tank is low
9. Engine coolant
Indicates engine temperature
About 180F
10. Starter switch
Rotates engine to start
Momentary ON
11. Throttle
Controls engine speed (rpm)
(See Tachometer)
550 rpm (idle)
12. Tachometer and
Indicates engine speed (rpm) and
operating-time meter
elapsed operating time
2000 rpm (normal)
13. Fuel shutoff
Cuts off fuel supply to engine
ON-OFF
14. Oil pressure gauge
Indicates engine oil pressure
30 to 60 psi
15. Voltmeter
Indicates operation of alternator
Variable
and battery condition
16. Selector switch
Selects operating modes
As desired
Place in UP
17. Emergency stop switch Stops unit in emergency situations
position to stop
(not on units with HKQ without allowing for engine cool-
unit
serial numbers)
ing or refrigeration pump down
11-21
