Pilatus PC-12, Manual

Page: 59 / 69

Component Maintenance Manual
EFFECTIVITY: ALL 21-00-22
Page 11002
JULY 21, 2011
12.1.4 Gain access to the Evaporator Coil Assembly (refer to the aircraft maintenance manual for
removal of access panels and other hardware that might need to be removed)
12.1.5 Remove all shrouds, covers or enclosures which prevent access to the evaporator
expansion valve adjustment knob.
12.1.6 Remove expansion valve protective cap.
12.1.7 Verify that inlet to evaporator coil and blower ducting are free of any contamination or
restrictions which could alter air flow. If components are dirty, refer to Cleaning, Section 6.
12.1.8 Verify the blower speed switch is in the high position.
12.1.9 Verify R12 manifold gauges and hoses are connected to the compressor service valves and
system is operating normally.
12.1.10 Close cabin and cargo doors and allow system to operate for 5 minutes.
12.1.11 Record compressor suction and discharge pressures and evaporator air inlet and outlet
temperatures.
NOTE : Typical temperature difference of evaporator inlet and outlet air is 25±5°F.
12.1.12 If the suction pressure is above the typical values outlined Table 4, the expansion valve
must be turned CCW in ½ revolution increments. Wait 2-5 minutes for valve to stabilize,
until desired value is obtained, or outlet temperature is the lowest possible.
12.1.13 If suction pressure is lower than typical values outlined Table 4, the expansion valve must
be turned CW in accordance with the same procedure discussed in previous paragraph.
12.1.14 Allow system to operate for 5-10 minutes after expansion valve adjustment to verify setting.
SUBTASK 21-00-22-82-002
12.2 Balancing Multiple Evaporators:
12.2.1 If system contains multiple evaporator modules, balancing of evaporators must be
accomplished for refrigerant flow between evaporators to achieve equal evaporator air
outlet temperatures. If system does not contain multiple evaporators, shut system off and
replace all shrouds, enclosures, ducting, as required and remove charging/measurement
equipment.
12.2.2 Gain access to all system evaporator’s. Measure and record outlet air temperatures.
12.2.3 Adjust the expansion valve on the evaporator with the highest outlet air temperature ¼
revolution in a CW direction. This will increase the refrigerant flow and reduce the outlet air
temperature.
12.2.4 Adjust the remaining evaporator(s) with a lower outlet air temperature ¼ revolution CCW.