Component Maintenance Manual
12037 N Highway 99
Seminole, OK 74868
Phone (405) 382-0731
Fax (405) 382-0737
http://www.enviro-ok.com
SUBTASK 21-00-23-82-002
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.
12.2.5 Allow system to stabilize, recheck the evaporator outlet temperatures and repeat adjustment
procedure if required. Evaporator outlet temperatures should be within 1-3° of each other.
NOTE: Proper evaporator balancing should not result in a change of the compressor suction pressure. Verify
system pressures are typical values as shown in table 5.
12.2.6 If the evaporator’s outlet temperature is equal and the suction pressure is typical, then
servicing is complete. Shut system off and replace all shrouds, enclosures, ducting, as
required and remove charging/measurement equipment. If not, repeat adjustment
procedure until temperatures are equal and suction pressure is typical.
SUBTASK 21-00-23-82-003
12.3 Motor Insulation Resistance Check:
12.3.1 After the inspection of the commutator, a quick check of the motor insulation resistance
should be performed. This check may be done with or without the brushes installed, but the
power leads must be removed from the motor during this procedure.
12.3.2 Gain access to the Compressor Condenser Module (refer to the aircraft maintenance
manual for removal of access panels and other hardware that might need to be removed)
12.3.3 Verify that power is removed from aircraft. If it is not practical to remove aircraft power,
technician must pull and collar applicable circuit breakers.
12.3.4 With OHM meter positive lead connected to the motor positive terminal and the other lead
connected to motor case (grnd), measure and record resistance. Resistance value must be
equal to or greater than 10,000 OHM’s. If less, the motor should be replaced.
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