Refrigerant Piping.

TM 5-4120-355-14

c. lasting. Test for continuity with multimeter set on OHMS. Refer to wiring diagram figure 1-3 to establish points

of continuity.

d. Installation. Refer to figure 4-10 and install electrical heater thermostat.

4-40. Refrigerant Piping.

a. Inspection. Inspect refrigerant piping for kinking, holes, and unsatisfactory welding.

b. Testing.

(1) Halide torch leak detector. The preferred method of field testing for leaks in the refrigeration system is by

using a halide torch of any available tester. Operate the air conditioner, paragraph 2-2, and pass the explor-

ing tube slowly over the sweat fittings, mechanical couplings, and valves. If refrigerant is leaking from the sys-

tem, the flame of the torch will change from blue to green when the leak is small. If the leak is large, the

flame will be a deep blue with a reddish tip or the flame may be entirely extinguished.

(2) Soap solution method. Operate the air conditioner, paragraph 2-2, Brush all points of possible leakage

with soap solution. Watch for bubbles. Follow a definite sequence so that all joints will be thoroughly tested.

Wipe the solution from all joints and mark any spot where Ieakage occurs.

441. Liquid Line Solenoid Valve.

a. General. The liquid line solenoid valve is automatically actuated by the thermostat and controls the flow of

refrigerant to the evaporator coil.

b. Inspection. Inspect for cracked or broken casing and damaged or broken terminals, figure 4-7.

c. Testing. Test for continuity across coil with multimeter set on OHMS. Refer to wiring diagram figure 1-3 to

establish points of continuity.

442. Equalizer Solenoid Valve.

a. General. The equalizer solenoid valve is actuated by the on-off switch and serves to equalize system pressure

during shutdown.

b. Inspection. Inspect for cracked or broken casing and damaged or broken terminals, figure 4-10.

c. Testing. Test for continuity across coil with multimeter set on OHMS. Refer to wiring diagram figure 1-3 to es-

tablish points of continuity.

443. Access Fittings.

a. General. The two access fittings (suction line and discharge line) provide access to the refrigerant system, figure

4-7.

b. Inspection. Inspect for cracked casing or damaged threads.

444. Pressure Relief Valve.

a. General. Pressure relief valve (fig. 4-7) is located on a tee just below the filter-drier. The pressure relief valve pro-

tects the refrigerant system from excessive pressure.

b. Inspection. Inspect for cracked or broken casing.

445. Pressure Regulating Valve.

The evaporator pressure regulating valve, fig. 4-10 regulates refrigerant pressure in the evaporator to prevent coil

freeze UP. The valve is preset to establish a minimum pressure in the evaporator of 58 psig.

4-26