EXPANSION VALVE (PRIMARY) INSPECTION AND TEST.

TM 5-4120-369-14

4-40.

General. If the air conditioning unit is not cooling properly, inspect and test the

expansion valve for defects.

Inspection,

( 1 ) Refer to paragraph 4-8 and remove top covers.

( 2 ) Refer to figure 4-26 and check that the required length of the expansion valve's

sensing bulb is fully in the suction line bulb well.

( 3 ) Refer to figure 4-26 and examine the flow restrictor capillary tubes carefuIly.

They should be very COld and evenly frosted. Unfrosted tubes are blocked and should be-

replaced.

(4) If the capillary tube is cold and frosted, the valve is blocked or the valve's

power assembly is ruptured, The test for the power assembly is listed in the following paragraph.

Test the power assembly by removing the valve's sensing bulb from the

Test.

suction bulb well (figure 4-26). Hold the sensing bulb firmly in both hands for two or three

minutes. The warmth from holding the bulb should put enough pressure on the bellows to

start the refrigerant flowing into the system. If cooling does not commence, the expansion

valve is defective and should be replaced. Report all defects to Direct Support maintenance.

4-41.

COMPRESSOR

REFRIGERANT UNDER PRESSURE

is used in this equipment Organizational personnel

are not authorized to open the pressurized system.

HIGH VOLTAGE

is used in the opertion of this equipment

DEATH ON CONTACT

or severe injury may result if personnel fail to

observe safety precautions. Always disconnect

the air conditioner from power source before per-

forming maintenance on this equipment. If power

must remain on for troubleshooting, exercise

extreme care to avoid contact with any electrical

component, fan, fan motor, etc. Do not operate

the air conditioner without louvers, top controls,

and guards in place and tightly secured.

General. The compressor is a hermetically sealed unit and is not repairable. An

inoperative compressor is usually due to a mechanical failure causing the compressor to freeze,

a control failure, or motor burnout. Compressor replacement is required in all cases of

mechanical or motor burnout. If the motor is defective, report to Direct Support maintenance.

Test.

(1) Refer to paragraph 4-18 and remove the top covers.

(2) Disconnect receptacle connector.

(3) Refer to wiring diagram (FO-1) and test for continuity using a multimeter. Lack

of continuity indicates an open winding. Report to Direct Support Maintenance.

(4) Place one contact of the multimeter against the compressor housing and the other

against the motor terminals, one at a time. If a circuit is indicated, the motor is grounded.

Report to Direct Support maintenance.

4-48