TM 9-4120-401-14
Table 4-2. UNIT TROUBLESHOOTING - continued
MALFUNCTION
TEST OR INSPECTION
C O R R E C T I V E ACTION
REDUCED COOLING CAPACITY.
Step 1. Check that all doors, windows, and other openings in the room or enclosure are tightly closed.
Tightly close all openings.
Step 2. Check position of potentiometer TEMPERATURE control.
Set control at maximum COOL; then, if condition improves, adjust properly.
Step 3. Check that the louvers in the conditioned air intake and discharge grilles are properly adjusted.
(Must be open.).
Adjust louvers properly,
Step 4. Check to be sure that excessive hot, outside air is not being introduced through the fresh air
damper.
Fully close damper; then, if condition improves, adjust properly.
Step 5. Check to be sure condenser air intake and discharge are not obstructed.
Remove obstructions.
Step 6. With unit operating in COOL mode, check rendition of refrigerant in sight glass,
(1) If color is yellow or a light hue of chartreuse, or if numerous bubbles appear, turn air
conditioner OFF/RESET, and notify supervisor.
(2) If color is green or a dark hue of chartreuse, but has a milky appearance, or more than
an occasional bubble appears, thoroughly clean the condenser intake screen,
condenser fan guard, condenser coil, and entire condenser section to remove all
obstructions.
Step 7. Check airflow out of conditioned air (evaporator) discharge grille. If air flow volume is low:
(1) Adjust conditioned air (evaporator) intake grille louvers
(2) Clean and service, or replace conditioned air filter element. (See paragraph 4-18.)
Clean or replace as indicated.
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