TM 9-4120-395-14&P
5-11. REFRIGERANT PRESSURE CHECK - Continued.
NOTE
Both gages should read the same. Check the reading with the appropriate column in Table 5---2. if the system is even
partially charged, the pressure should be approximately equal to that shown in the table for the appropriate ambient
temperature. If the pressure is considerably less than shown in the table perform a leak test per para 5-8.
g.
Turn the thermostat system switch to (COOL with the thermostat cooling lever at the lowest setting and allow
the system to stabilize (about 3 minutes).
h.
Check the gages.
If the discharge and suction pressures are at, or near, the same value, a reversing valve malfunction or an internal
compressor failure is indicated. See para 5-19 and 5 -20.
discharge pressure is low and suction pressure is normal, a low refrigerant charge Indicates(: See: para 5-10.
If discharge pressure is normal and suction pressure is either high or low, failure of the ;check valve is Indicated. See
discharge pressure is high and suction pressure is normal', a malfunction of a fan (see para 4-37 and 4-4t). refrigerant
i.
Turn the thermostats system switch to OFF.
j.
Close both service valves on unit.
k.
Remove gages or service manifold hoses from service valves.
1. Install the valve stem .and hose connection protective caps.
m. Proceed with ;any required maintenance action.
5-19