DIRECT SUPPORT MAINTENANCE
AIR CONDITIONER, HORIZONTAL, COMPACT
REFRIGERANT PRESSURE CHECK
Goggles, WP 0000 00, Item 2
Gloves, WP 0000 00, Item 2
Install service manifold
Refrigeration Unit Service Tool Kit, WP 0000 00, Item
1. Check that the unit HIGH and LOW pressure charging valves are open and all four service manifold valves are
2. Both gages should read the same. Check the reading with the appropriate column in Table 1. If the system is
partially charged, the pressure should be approximately equal to that shown in the table for the appropriate ambient
temperature. If the pressure is considerable less than the reading shown in Table 1, the system does not contain
enough refrigerant to continue the pressure check; proceed directly to leak testing (See WP 0069 00).
3. Turn the air conditioner on and operate in COOL mode with the TEMPERATURE SELECTOR at the fullest cooler
setting for five minutes.
4. Allow gages to stabilize and take readings of the two gages.
If the discharge and suction pressures are at (or near) the same valve, a pressure equalizer solenoid valve L2 or compressor
failure is indicated.
If discharge pressure is low and suction pressure is normal, a low refrigerant is indicated (Table 2).
b) If discharge pressure is normal and the suction pressure ids either high or low, failure or maladjustment of
the pressure regulator valve is indicated (Table 2).
c) If ice forms on the evaporator coil, or evaporator coil does not cool during operation, failure or malfunction
of the evaporator expansion valve is indicated.
d) If the discharge pressure valve is high and suction pressure is normal, a malfunction of quench the valve is
e) If the discharge pressure is above 540 psi, the pressure relief valve malfunction is also indicated.
5. When pressure tests are completed, turn the unit off and proceed with any maintenance action indicated.