Components; Compressor Assembly - MD Helicopters MD Explorer Servicing And Maintenance

1. Air Conditioning System
The air conditioning system supplies ventila­
tion, temperature, and humidity control to the
cabin.
Configuration - There are two configura­
tions of the air conditioning system. They are
identified in this manual as the early configu­
ration (EARLY CONFIG) and current
configuration (CURRENT CONFIG). Those
areas in which a configuration is not specified
are the same for both configurations.
EARLY CONFIG - This configuration has
two condenser fans and one condenser. The
fans and condenser are under the floor in the
baggage compartment.
The receiver dehydrator is on the right side of
the transmission deck. This configuration is in
use by aircraft with the PW206A/E engine.
CURRENT CONFIG - This configuration has
no condenser fans and two condensers. The
condensers are attached to the oil coolers.
The receiver dehydrator is on the left side of
the transmission deck. This configuration is in
use by aircraft with the PW207E engine.
A. Components
The air conditioning system contains the
components that follow:
Utility Control Panel - The five position
rotary-switch AC/VENT controls the vent fan
and air conditioning. The COOL HIGH
switch position supplies air conditioning at a
high volume. The COOL LOW switch position
supplies air conditioning at a low volume.
Compressor Assembly - Compresses the air
conditioning refrigerant. The compressor
changes the refrigerant from a low pressure
and temperature gas to a high pressure and
temperature gas.
Lines and Tubing - Transfer the refrigerant
through the air conditioning system.
MD Helicopters, Inc.
Rotorcraft Maintenance Manual
AIR CONDITIONING SYSTEM
DESCRIPTION AND OPERATION
Condenser Fans (EARLY CONFIG) -
The two fans provide ambient airflow across
the condenser.
Cooling Blowers (CURRENT CONFIG) -
The two blowers provide ambient airflow
across the condensers.
Condenser - Changes high-pressure refriger­
ant gas into high-pressure refrigerant liquid.
Receiver Dehydrator - Removes moisture
from the refrigerant liquid.
High Pressure Switch - De-energizes the
compressor in a high pressure condition.
Prevents damage to the air conditioning
system.
Low Pressure Switch - De-energizes the
compressor in a low pressure condition.
Prevents damage to the air conditioning
system.
Thermostatic Switch - Prevents the
evaporator from too much refrigeration or an
icing condition.
Thermal Expansion Valve - Controls the air
conditioning system refrigerant that is put into
the evaporator.
Evaporator - Supplies the cabin with fresh or
recirculated air.
Evaporator Fan - Pushes air through the
evaporator.
Three Way Valve-Duct Assembly - Controls
the flow of recirculated or external air to the
air conditioning system.
Three Way Valve Control Cable - Controls
the position of the three way valve.
B. Compressor Assembly
The compressor is on the right engine accesso­
ry gearbox.
The compressor is a shaft driven unit. The
internal drive shaft is controlled by a clutch.
The internal drive shaft will break away from
the gearbox if the compressor seizes. This
prevents damage to the engine.
21-50-00
CSP−900RMM−2
Page 1
Revision 8