TM 9-4120-388-14
5-12. CHARGING THE REFRIGERATION SYSTEM - Continued.
f.
Close the low pressure (suction) charging manifold valve. Never introduce liquid refrigerant into the low pressure
(suction) service valve.
Position the refrigerant-22 drum so that lquid will be used for charging. (Some drums must be inverted and
g.
some are equipped with a selector valve).
h.
Using accurate scales, measure and record the weight of the refrigerant-22 drum.
i.
Open the refrigerant-22 drum valve.
Open the high pressure service valve on the air conditioner. Allow liquid refrigerant to enter the system until
j
the drum weight has decreased by 4 pounds (1.8 kg) or until system pressure has equalized.
k.
Close the refrigerant drum valve and the high pressure (discharge) manifold valve.
l.
Connect air conditioner to a remote control module assembly.
m.
Connect power.
Press and release both pressure switch reset buttons.
n.
Turn air conditioner on and operate in the COOL mode with the Temperature control thermostat set at a maxi-
o.
mum DECREASE position.
if the 4 pound (1.8 kg) full charge was obtained, skip steps q through s. if the system pressure equalized prior
p.
to obtaining a full charge of 4 pounds (1.8 kg), proceed with step q.
Switch the refrigerant drum to the gas only position.
q.
r.
Be sure that the refrigerant drum has been switched to the gas position and open the refrigerant drum valve, the
low (suction) pressure charging manifold valve, and the low (suction) pressure service valve on the air conditioner.
Monitor the weight of the refrigerant drum as the air conditioner compressor pulls additional refrigerant gas into
s.
the system until the full 4 pound (1.8 kg) charge is obtained. When the system is fully charged, immediately
dose the air conditioner low pressure service valve and the refrigerant drum valve.
Do not skip the next step. Failure to wait could give an erroneous reading.
Run the air conditioner in COOL mode (with Temperature control thermostat in full DECREASE position) for
t.
15 minutes.
After 15 minutes, observe the sight glass on back of condenser section.
u.
(1) Green center means the refrigerant moisture content is acceptable.
(2) Yellow center means there is too much moisture in the system. It must be discharged, evacuated, and
charged again.
(3) Milky while or bubbly liquid means the system has a low charge.
(4) Clear bubble-free liquid around the center means the system is fully charged.
v.
if charge is low, add gas refrigerant.
(1) Be sure that drum is switched to gas position. Open the drum valve and the air conditioner low pressure
service valve.
(2) Continue to charge until sight glass is dear and bubble-free.
(3) Close the air conditioner low pressure service valve and refrigerant drum valve.
w.
Check air conditioner for proper cooling. There should be at least a 15F temperature difference between evap-
orator discharge air and the inlet air. Turn the mode selector switch to OFF.
x.
Assure that the high and low pressure air conditioner service valves are closed and remove the charging man-
ifold hoses from the air conditioner service valves.
5-25
