TM 5-3805-290-23-1
AIR CONDITIONING SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
0018 00
REFRIGERANT QUICK-CHECK PROCEDURE FOR R-134A EXPANSION
VALVE AND ORIFICE TUBE SYSTEMS - CONTINUED
0018 00
N OT E
If outlet is warmer than inlet, system may not contain enough refrigerant.
(1)
Recover refrigerant (WP 0191 00).
(2)
Evacuate system (WP 0191 00).
(3)
Charge system with correct amount of refrigerant. Measure refrigerant by weight (WP 0191 00).
(4)
Perform a leak test. Refer to Refrigerant Leakage Test in this work package.
(5)
Perform a performance check. Refer to Performance Checks for Air Conditioning System in this work
package.
PERFORMANCE CHECKS FOR AIR CONDITIONING SYSTEM
0018 00
N OT E
A performance check of AC system must be made with a manifold gage set. Manifold gage set must be con-
nected to diagnostic connectors on compressor.
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 5-3805-290-10).
a.
During normal operation of AC system in 70F (21C) temperature, discharge (high pressure test fitting) pressure
will be 120 to 190 psi (820 to 1,300 kPa), suction (low pressure test fitting) 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.
In very hot weather, suction and discharge pressures will be high. In cooler weather, suction and discharge pressure
will be normal or pressure can be lower.
c.
