Component Maintenance Manual
12037 N Highway 99
Seminole, OK 74868
Phone (405) 382-0731
Fax (405) 382-0737
http://www.enviro-ok.com
• Verify that system leak check and refrigerant charging has been performed and system is
operating at typical values as outlined in table 5.
Table 5 Typical Operating Values
12.1.3 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)
12.1.4 Remove all shrouds, covers or enclosures which prevent access to the evaporator
expansion valve adjustment knob.
12.1.5 Remove expansion valve protective cap.
12.1.6 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 7.
12.1.7 Verify the blower speed switch is in the high position.
12.1.8 Verify R-134A manifold gauges and hoses are connected to the compressor service valves
and system is operating normally.
12.1.9 Close cabin and cargo doors and allow system to operate for 5 minutes.
12.1.10 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.
12.1.11 If the suction pressure is above the typical values outlined Table 5, 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.
12.1.12 If suction pressure is lower than typical values outlined Table 5, the expansion valve must
be turned CW in accordance with the same procedure discussed in previous paragraph.
12.1.13 Allow system to operate for 5-10 minutes after expansion valve adjustment to verify setting.
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