Outside Air Thermostat - TM-5-4120-274-150050

TM 5-4120-274-15

d. Installation. Refer to figure 3-10, 3-11 and

install electric heater thermostat.

3-45. Refrigerant Piping

a. Inspection. Inspect refrigerant piping for

kinking, holes and unsatisfactory welding.

b. Testing.

(1) Halide torch leak detector. The pre-

ferred method of field testing for leaks in the

refrigeration system is by using a halide torch.

Operate the air conditioner (fig. 2-3) and pass the

exploring tube slowly over all sweat fittings, me-

chanical couplings, and valves. If refrigerant is

leaking from the system 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 (fig. 2-3). Brush all points of possi-

ble 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 leakage occurs.

Figures 3-14. Fan speed pressure switch removal and

3-46. Liquid Line Solenoid Valve

installation.

a. General. The liquid line solenoid valve is

automatically actuated by the thermostat and con-

3-43. Outside Air Thermostat

trols the flow of refrigerant to the evaporator

a. General. The outside air thermostat is

coil.

mounted to the rear housing of the air condition-

b. Inspection. Inspect for cracked or broken

er. It prevents the compressor from being started

casing and damaged or broken terminals.

when the outside temperature is below 50F. This

c. Testing. Test for continuity across coil with

prevents the unit from being operated at a time

multimeter set on OHMS. Refer to wiring dia-

when low condensing and suction pressures will

gram figure 1-5 to establish points of continuity.

hamper system operation.

b. Removal. Remove outside air thermostat as

illustrate on figure 3-13.

3-47. Equalizer Solenoid Valve

c. Testing. Test the thermostat for continuity

a. General. The equalizer solenoid valve is ac-

with a multimeter set on OHMS. Refer to the

tuated by the on-off switch and serves to equal-

wiring diagram figure 1-5 for the points to estab-

ize system pressures during shutdown.

lish continuity.

b. Inspection. Inspect for cracked or broken

d. Installation. Refer to figure 313 and install

casing and damaged or broken terminals.

outside air thermostat.

c. Testing. Test for continuity across coil with

multimeter set on OHMS. Refer to wiring diagram

3-44. Electric Heater Thermostat

figure 1-5 to establish points of continuity.

a. General. The electric heater thermostat

(fig. 3-11) protects the heater elements from

3-48. Access Fittings

overheating.

a. General. The two access fittings (suction

b. Removal. Refer to figure 310, 3-11 and re-

line and discharge line) provide access to the re-

move electrical heater thermostat.

frigerant system, figure 3-6.

c. Testing. Test for continuity with multimeter

b. Inspection. Inspect for cracked casing or

set on OHMS. Refer to wiring diagram figure

damaged threads.

1-5 to establish points of continuity.

3-18