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Malfunction
7. Discharge pressure too high,
8. Suction and discharge pressure low.
9. High suction pressure with low dis-
charge pressure.
10. System losing cooling capacity.
11. Sight glass indicates CAUTION or
WET.
Table 5–1. — Continued
Probable cause
Expansion valves defective or out
of adjustment.
Compressor defective.
Insufficient volume of air passing
through condenser coil.
Refrigerant overcharged.
Defective solenoid valve.
Incorrectly set or defective expan-
sion valves.
Lack of refrigerant.
Insufficient airflow across evapora-
Corrective action
Replace or adjust valves as re-
quired (para 5-17 or 5-18).
Replace compressor (para 5-23).
Service condenser coil and screen
(para 3-8).
Remove small amount of refriger-
ant.
Replace (para 5-14).
Adjust or replace (para 5–17).
Check refrigerant level in sight
glass. Test for leaks and charge
system (para 6-5. )
Check evaporator discharge and
return air grilles, air filter, mist
eliminator and evaporator coil
for dirt or other obstructions.
Service (para
3-6, 3-7, and
3-8 ).
Replace compressor (para 5-23).
a. Check suction and discharge pres-
sures (table 5–2 and para 6-6).
tor coil.
Compressor defective.
a. Suction or discharge pressure not
correct.
b. Ice on coil.
I
, b. Check pressure regulating valve.
Moisture in refrigerant system.
Perform leak test (para 6–5), replace
dehydrator (para 5-21), evacuate,
and charge system (para 6-5).
Table 5-2. Normal Operating Pressures
95° F RETURN AIR TO UNIT
Outdoor Ambient Temperature
50° F
75” F
100° F
110° F
125° F
Gage Pressures:
Suction
5 6 - 6 0
56—65
65—75
70-80
75—90
Discharge
135—155
185—205
275—295
375—380
400-420
80° F RETURN AIR TO UNIT
Outdoor Ambient Temperature
50° F
75 0 F
100° F
125° F
Gage Pressures:
Suction
minimum 56
minimum 56
56-65
65-75
Discharge
130-150
180-200
270-290
290-410
Section V. REMOVAL AND INSTALLATION OF MAJOR
COMPONENTS AND AUXILIARIES
5-9. Evaporator Coil
b. Installation.
(1) I n s t a l l t h e e v a p o r a t o r c o i l i n r e v e r s e
a. Removal.
order of removal.
(1) Discharge the refrigerant system (para
(2) Pressure test, evacuate, and recharge
6-3).
the refrigerant system (para 6-5).
(2) Refer to figure 3-4 and remove the dis-
charge grille and top access cover.
5-10. Condenser Coil
(3) Refer to figure 3-5 and remove the mist
eliminator.
a. Removal..
(4) Remove
(5) Refer to
orator coil.
the condenser fan (para 3-24).
(1) Discharge the refrigerant system (para
figure 5-1 and remove the evap- 6-3
(2) Remove the condenser fan (para 3-24).
5-3
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