Pressure Relief Valve - TM-5-4120-274-150051

TM 5-4120-274-15

the changing of the color code from green to yel-

3-49. Pressure Relief Valve

low.

a. General. Pressure relief valve (fig. 3-6) is

located on a tee just below the filter-drier. The

3-53. Liquid Receiver

pressure relief valve protects the refrigerant sys-

Inspect for cracks or broken casing.

tem from excessive pressure.

b. Inspection. Inspect for cracked or broken

casing.

3-54. Evaporator Coil (fig. 3-15).

a. General. The evaporator coil is mounted on

3-50. Pressure Regulating Valve

the casing, directly behind the discharge grille.

The coil must be removed from the air conditioner

The evaporator pressure regulating valve figures

for repair or replacement. The mixture of fresh

3-10, 311 regulates refrigerant pressure in the

air and re-circulated air is passed through the

evaporator to prevent coil freeze up. The valve

evaporator coil and forced into the conditioned

is preset to establish a minimum pressure in the

air space by the evaporator fan.

evaporator of 58 psig.

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

with halide torch for refrigerant leaks.

3-51. Expansion Valves

c. Inspection and Cleaning.

a. General A 1-ton expansion valve controls

(1) Inspect coil for bent fins, cracks or

the rate of flow of liquid refrigerant into the evap-

breaks, solder any cracks. Straighten bent fins

orator coil during the cooling cycle of operation

with coil comb or thin nose pliers.

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

(2) Clean coil with low pressure, compressed

(fig. 3-11, 3-12) valve functions when the unit

air.

is in tie bypass cycle of operation.

b. Inspection.

d. Removal.

(1) Check for loose or leaking connections.

(1) Remove top panel and discharge grille,

(2) Make sure the thermal bulb is securely

refer to paragraph 318.

fastened and is covered with rubber insulation.

(2) Refer to figure 3-15 and remove the

evaporator coil.

3-52. Sight Glass

e. Installation.

a. General. The sight glass indicates the refrig-

(1) Install the evaporator coil refer to fig-

erant is indicated by flash gas in sight glass (fig.

ure 3-15.

3-13).

(2) Install the top panel and discharge

b. Inspection. Inspect for excessive moisture

grille, refer to paragraph 3-18.

in refrigerant. Excessive moisture is indicated by

Figure 3-15. Evaporator removal and installation.

3-19