EXPANSION VALVE. - TM-5-4120-364-130066

TM 5-4120-364-13

f. Open the system discharge valve about 2 turns and allow pressure to

equalize.

Start unit and run until 13 pounds 18 ounces o f r e f r i g e r a n t R - 1 2 i s a d d e d .

h. Backseat suction service valve.

i . Close refrigerant cylinder valve and remove c h a r g i n g l i n e f o m v a l v e .

EXPANSION VALVE.

4-11.

a . I n s p e c t . I n s p e c t the expansion valve l o c a t e d i n a b r a c k e t o n the side of

t h e evaporator coil for damage which would impair s e r v i c e a b i l i t y .

b. A d j u s t

CAUTION

N e v e r adjust the expansion valve unless ab-

s o l u t e l y n e c e s s a r y . W h e n adjusting the ex-

p a n s i o n valve allow at least 20 minutes be-

t w e e n each adjustment. Insure t h a t a l l p a n e l s

are in place.

( 1 ) Tape the bulb of a thermometer to the suction line near the sensing

e l e m e n t of the expansion valve.

( 2 ) Install a pressure g a g e t o i n d i c a t e s u e t i o n p r e s s u r e .

( 3 ) Operate the unit on cool for approximately 30 minutes t o

stabilize

thermometer reading.

(4)

Check thermometer and pressure gage. To the suction pressure, add

e s t i m a t e d suet

ion line loss (2 psi). Convert this refrigerant R-12 suction pressure

t o temperature

and subtract from temperature indication of suet ion line. The super-

h e a t should be

10 degrees.

( 5 ) Remove seal cap on side of expansion valve and turn adjusting screw.

T u r n i n g adjusting screw to the left increases f l o w and lowers superheat. Turning

a d j u s t i n g screw to the right decreases flow and raises superheat. Four complete

turns will raise or lowr superheat by approximately 2 degrees.

c. R e p l a c e . T h e e x p a n s i o n v a l v e m a y b e r e m o v e d f r o m t h e d i s t r i b u t o r w h i c h

i s an integral part of the evaporator coil. To remove and replace the expansion

valve, see figure 44.

4-12.

EVAPORATOR COIL ASSEMBLY .

a . General.

T h e evaporator coil assembly may be removed from its section

without disassembly of other sections of the unit. Normally, the expansion valve,

distributor, suction header and equalizer line are removed as a part of the evapor-

ator coil assembly. (See figure 4-5).

4-10