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
0018 00
N OT E
In order to use this procedure, temperature of ambient air must be at least 70F (21C).
1.
Start engine and run engine at approximately 1,000 rpm. Move control knob on air conditioner to position of MAXI-
MUM so cooling is at a maximum in order to stabilize system, put fan switch in HIGH position and operate system for a
minimum of 10 minutes (TM 5-3805-290-10).
2.
Check for restrictions present in refrigerant lines from compressor to inline dryer. Refrigerant lines and components that
are high pressure and high temperature come from outlet side of compressor. Lines go to inlet side of orifice tube. Outlet
side will be warm during normal operation. Heavy frost or a decrease in temperature in a line or in a component on high
pressure side may be an indication of a restriction or blockage.
a.
If there is no evidence of a restriction in condenser coil, inline dryer, or refrigerant lines from compressor to inline
dryer, use procedure in step 3.
b.
If there is a restriction in condenser coil, inline dryer, or refrigerant lines from compressor to inline dryer, perform
the following procedures:
(1)
Recover refrigerant (WP 0191 00).
(2)
Remove restriction or replace component (WP 0193 00 thru WP 0195 00).
(3)
Evacuate system (WP 0191 00).
(4)
Charge system with correct amount of refrigerant (WP 0191 00).
(5)
Perform a leak test. Refer to Refrigerant Leakage Test in this work package.
(6)
Perform a performance check. Refer to Performance Checks for Air Conditioning System in this work
package.
(7)
If problem still exists go to step 4.
3.
Low system charge is indicated. Perform a leak test.
N OT E
If system is very low on refrigerant, a partial charge may be needed before you perform a leak test.
a.
Recover remaining refrigerant (WP 0191 00).
b.
Repair all leaks.
c.
Evacuate system (WP 0191 00).
d.
Charge system with correct amount of refrigerant. Measure refrigerant by weight (WP 0191 00).
e.
Perform a performance check. Refer to Performance Checks for Air Conditioning System in this work package.
f.
If problem still exists, go to step 4.
4.
Feel low pressure line and feel high pressure line at compressor. In order to indicate normal systems operation, high
pressure line to condenser coil must be warm, while low pressure line to evaporator coil must be cool.
a.
High pressure line and low pressure line at compressor have a minimal temperature difference between two lines.
Use procedure in step 5.
b.
If there is a definite temperature difference between high pressure line and low pressure line at compressor, system
is operating correctly. High pressure line will be warm. Low pressure line will be cool. Use procedure in step 6.
