Expansion Valves.

TM 5-4120-355-14

4-46. Expansion Valves.

a. General. A 1-ton expansion valve controls the rate of flow of liquid refrigerant into the evaporator coil during

the cooling cycle of operation (fig. 4-10). The one-half ton expansion valve functions when the unit is in the by pass

cycle of operation.

b . Inspection.

(1) Check for loose or leaking connections.

(2) Make sure the thermal bulb is securely fastened and is covered with rubber insulation.

4-47. Sight Glass.

a. General. The sight glass indicates the refrigerant moisture content. A shortage of refrigerant indicated by flash

gas in the sight glass (fig. 4-13).

b. Inspection. Inspect for excessive moisture in refrigerant. Excessive moisture is indicated by the changing of

the color code from green to yellow.

4-48. Liquid Receiver.

a. Inspection. Inspect for cracks or broken casing, figure 4-7

4-49. Evaporator Coil.

a. General. The evaporator coil is mounted on the casing, directly behind the discharge grille. The coil must be

removed from the air conditioner for repair or replacement. The mixture of fresh air and recirculated air is passed through

the evaporator coil and forced into the conditioned air space by the evaporator fan.

b. Testing. Refer to para 44- and test with halide torch for refrigerant leaks.

c. inspection and Cleaning.

(1) Inspect coil for bent fins, cracks, or breaks; solder any cracks. Straighten bent fins with coil comb or thin

nose pliers.

(2) Clean coil with coil comb or thin nose pliers.

d. Removal.

(1) Remove top penal and discharge grille, refer to para 4-15.

(2) Refer to figure 4-10 and remove evaporator coil.

e. Installation.

(1) install the evaporator coil, refer to figure 4-10.

(2) Install the top penal and discharge grille, refer to para 4-15.

4-50. Condenser Coil.

a. General. The condenser coil is mounted on the bottom rear of the casing, directly behind the condenser fan.

The coil must be removed from the air conditioner for repair or replacement. The coil is made from copper tube and

aluminum fin and is of fin-tube configuration.

4-27