(1) Circuit Breaker. The circuit breaker is designed to trip whenever an electrical overload or short circuit exists
in the compressor circuit. The circuit breaker itself is located in the junction box, but it is reset by means of a pushpull
flexible cable. (See figure 2-1). When it is suspected that the circuit breaker has tripped, pull then push the operating knob to
re-establish current to the air conditioner. If the circuit breaker cannot be reset, or if it trips as soon as it is reset, report the
trouble to Unit maintenance.
(2) High-pressure Cutout Switch. The high-pressure cutout switch is mounted in the upper section of the rear
surface of the air conditioner. A manual reset button and instruction plate provide for resetting the switch after it has tripped,
Press and release the button to reset the switch. If ineffective, report the trouble to Unit maintenance. (See figure 2-l).
(3) low-presswe Cutout Switch. The low-pressure cutout switch is located next to the high-pressure cutout
switch, but trips when refrigerant pressure drops below a preset minimum. Press and release the button to reset the switch. If
ineffective, report the trouble to Unit maintenance. (See figure 2- 1).
Only one indicator is incorporated in the air conditioner: the sight-glass liquid indicator. This circular window into the re-
frigerant liquid line shows the condition of the refrigerant. and should be inspected periodically, as directed in Section II. A
color comparison plate is mounted below the sight glass on the upper part of the rear casing. It shows green, chartreuse and
yellow bands to aid in evaluating the dryness of the refrigerant. If chartreuse or yellow colors are indicated, the refrigerant
contains moisture. If the sight glass shows a milky or bubbly appearance, the refrigerant volume is low. Both conditions
Section II. PREVENTIVE MAINTENANCE CHECKS AND SERVICES
Preventive maintenance checks and services are required to keep the air conditioner operating efficiently and to prevent
damage caused by neglect. Table 2-1 contains the listing of periodic checks and services required.
a. Before You Operate. Always keep in mind the CAUTIONS and WARNINGS. Perform your before PMCS.
b. While You Operate. Always keep in mind the CAUTIONS and WARNINGS. Perform your during PMCS.
c. After You Operate. Be sure to perform your after PMCS.
d. If Your Equipment Fails To Operate. Troubleshoot with proper equipment. Report any deficiencies using the
proper DA Form 2404 or refer to DA PAM 738-750.
Table 2-1. Operator Preventive Maintenance Checks and Services
Not Fully Mission Capable
Item To Be
Grilles are damaged.
Check all louvers and grilles for
unobstructed openings or damage.
Sight-glass broken or indi-
Check sight-glass for damage,
cates low refrigerant level
bubbles, milkiness, or yellow color.
Check for obstruction, dirt or dam-