TM 5-3805-291-23-1
AIR CONDITIONING SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
0018 00
PERFORMANCE CHECKS FOR AIR CONDITIONING SYSTEM
0018 00
N OT E
A performance check of AC sysem must be made with a manifold gage set. Manifold gage set
t
must be connected to diagnostic connectors on compressor.
Before you conduct a perormance check, refer to Visual Inspection in this work package.
f
1.
Use refrigerant reclaimer as manifold gage set.
N OT E
Most system failures are caused by improper refrigerant charge. Refrigerant charge should be measured
by weight only. Do not use gage pressure when you charge system with refrigerant.
2.
Start engine and operate engine at 1,000 rpm. Move temperature control knob to maximum cool position. Put fan switch
in HIGH position on AIR CONDITIONING side. In order to stabilize system, operate system for a minimum of 10 min-
utes. Operate engine at 1,000 rpm (TM 5-3805-291-10).
a.
During normal operation of AC system 70F (21C) weather, discharge (high pressure test fitting) pressure will be
120 to 190 psi (820 to 1,300 kPa). Pressure will be 10 to 20 psi (70 to 130 kPa). Refer to Table 1 for temperature
range. Outside temperature and humidity will have an effect on pressures. If outside temperature is high, discharge
pressure will be high.
b.
If very hot weather, suction and discharge pressures will be high. In cooler weather, suction (low pressure test fit-
ting) and discharge pressure will be normal or pressure can be lower.
If suction and discharge pressures are not within normal operating range, refer to Troubleshooting, Table 8 (WP
c.
