is reached. The normally closed compressor bypass valve is actuated open by the refrigeration valve and reroutes a
portion of the compressor discharge back on the compressor inlet. The refrigeration de-icing system prevents freeze-ups
due to ice formation on the evaporator core. The filter-drier provides filtered and dried refrigerant to the compressor to
cool the compressor motor and to lubricate the compressor bearings. The refrigerant level sight glass provides a means
for determining sufficient refrigerant in the system.
Access to the cooled air system is obtained by removing the condenser air inlet panels,
refrigeration compressors compartment access door, and opening the return air inlet door.
DO NOT break refrigerant lines or fittings for any purpose. Refer all maintenance and service
problems that require opening of refrigerant lines to direct support maintenance.
3-67. Recirculating Air and Fan Shroud Assembly (fig. 3-23)
Remove wiring harness connector from recirculating air fan. Remove three attaching bolts and washers
from fan shroud assembly and remove fan from power unit.
Remove 56 attaching bolts and washers from shroud assembly, separate from evaporator and remove
from power unit.
Installation. Install replacement recirculating air fan and fan shroud assembly in reverse order of removal
procedure. Reconnect wiring harness connector to fan.
3-68. Condenser Cooling Fan, Fan Mounting Plate and Shock Mount (Fig. 3-23)
Remove wiring harness connector from fan. Remove four attaching bolts, eight washers, and nuts.
Remove fan and fan mounting plate from power unit.
Remove four attaching bolts, eight washers, and four nuts from fan mounting plate and remove fan from
Remove two attaching bolts, four washers, and two nuts from shock mount and remove shock mount from
Install replacement fan, mounting plate, and shock mount in reverse order of removal procedure.
Connect wiring harness connector to fan.
For the condensers to perform their functions at peak efficiency it may be necessary to remove
dust, dirt, etc. from between the coil fins. Coil fins should be cleaned as required by flushing with
water or air pressure. Flush or blow out in opposite direction of normal air flow. Care should be
used so as not to damage coil surfaces.
Section XIII. HEATED AIR SYSTEM
The heated air system uses two independent control and mixing systems connected to a single source of heated air.
Each system uses hot compressed air from the gas turbine engine through the bleed load control valve. Each system is
capable of being operated independently, to provide one half of the total heat requirement, or together, to provide all the
total heat requirement. Each heated air system consists of a common compressed air source, a common bleed load
control valve, a common air pressure regulator, a common load control thermostat, a flow-control valve, an air mixing
chamber, two recirculating fans and connecting ducting, tubing and fittings. Compressed, heated air is bled from the gas
turbine engine turbine section through the bleed-air load control valve. The bleed load control valve remains closed at all
times unless bleed air for heating is required, at which time the valve is opened to supply heated compressed air. The
air pressure regulator supplies air to the load control valve to actuate the butter-fly valve. The load control thermostat
modulates the load control valve to prevent operation of the engine at power levels that would result in excessive
exhaust gas temperatures. The flow control valve permits the flow of hot bleed air from the load control valve to enter