Expansion Valves

TM 5-4120-273-15

orator coil and forced into the conditioned air

3-51. Expansion Valves

space by the evaporator fan.

A one-half ton expansion valve controls the rate

b. Testing. Refer to paragraph 3-45b and test

of flow of liquid refrigerant into the evaporator

with halide torch for refrigerant leaks.

coil during the cooling cycle of operation (fig.

c. Inspection and Cleaning.

3-11, 3-12). Another one-half ton expansion (fig.

(1) Inspect coil for bent fins, cracks or

3-11, 3-12) valve functions when the unit is in the

breaks. Solder any cracks and straighten bent fins

bypass cycle of operation.

with coil comb or thin nose pliers.

(2) Clean coil with low pressure compressed

3-52. Filter-Drier

air.

The filter-drier prevents the accumulation of

moisture and contaminants within the refrigerant

3-56. Condenser Coil

tubing. The filter-drier must be replaced each time

a. General. The condenser coil, refer to figure

the system is exposed to the atmosphere.

3-4, is mounted on the bottom rear of the casing,

directly beneath the condenser fan. The coil must

3-53. Sight Glass

be removed from the air conditioner for repair or

a. General. The sight glass indicates the refrig-

replacement. The coil is made from copper tube

erant moisture content. A stortage of refrigerant

and aluminum fin and is of the fin-tube configura-

is indicated by flash gas in the sight glass (fig. 3-

tion.

14).

b. Testing. Refer to paragraph 3-45b and test

b. Inspection. Inspect for excessive moisture in

with halide torch for refrigerant leaks.

refrigerant. Excessive moisture is indicated by the

c. Inspection and Cleaning.

changing of the color code from green to yellow.

(1) Inspect coil for bent fins, cracks or

breaks. Solder any cracks. Straighten bent fins

with coil comb or thin nose pliers.

3-54. Liquid Receiver (fig. 3-6)

(2) Clean coil with low pressure compressed

Inspect for cracks or broken casing.

air.

3-55. Evaporator Coil (fig. 3-16)

3-57. Drain Tubes

a. General. The evaporator coil in mounted on

a. Removal. Refer to figure 3-6 and remove

the casing directly behind the discharge grille. The

drain tubes.

b. Inspection and Servicing.

coil must be removed from the air conditioner for

(1) Inspect tubes for obstructions and loose

repair or replacement. The mixture of fresh air

and n-circulated air is passed through the evap-

connections.

Figure 3-16. Evaporator coil, removal and installation.

3-20