Inspecting Compressor Oil Level.

TM 5-4110-217-14

h Disconnect charging line from suction valve

6-6. Purging Refrigeration System.

and replace bonnet and nut

When the refrigeration system is opened for

Turn suction service valve clockwise until

servicing, there is a possibility of air entering the system

suction pressure gauge registers. j Return unit to normal

Before closing the system, that portion opened must be

operation.

purged to eliminate air.

a. Purging System when Unit has Lost Complete

Charge.

6-4. Inspecting Compressor Oil Level.

(1) Test for and repair leak.

Refrigeration oil In the unit travels through a sealed

(2) Attach charging line from drum of R-12 to

system and cannot escape It should be necessary to add

charging port of suction service valve.

oil only after repair of the refrigeration system. To

(3) Remove expansion valve outlet flare nut.

inspect compressor oil level, proceed as follows:

(4) Fully close suction service valve.

a Operate unit with 70 F air passing through

(5) Partly open valve on charging drum and

evaporator coil for twenty-five minutes

let gas enter system Refrigerant will travel through

b With unit running, inspect oil level through sight

compressor, discharge line, condenser, receiver, liquid

glass at side of compressor If oil can be seen in glass, oil

line, and expansion valve. Let gas pass through system

level is correct, if oil cannot be seen, oil must be added.

for ten seconds.

(6) Open compressor suction service valve 3

6-5. Adding Compressor Oil.

or 4 turns and close compressor discharge valve

(7) Partly open valve on charging drum and

To add compressor oil, proceed as follows

let gas pass through system for ten seconds The

a. Pump down compressor by closing suction

refrigerant will travel through the crankcase pressure

service valve Turn switch to "ON" momentarily until

regulating valve, heat exchanger, and evaporator

suction pressure gauge registers between 0- and 1-

(8) Replace expansion valve outlet flare nut.

pound per square inch Snap switch to "OFF" position.

(9) Return all service valves to normal

b. Close compressor discharge valve.

operating position.

c. Remove compressor oil filler plug and permit

(10) Charge system with refrigerant (para 6-3)

gas to escape through filler plug opening Never open

b. Purging Low Side of System. When unit has

compressor when suction pressure gauge registers a

been pumped down in order to service a part on the low

vacuum

side, and there is refrigerant in the receiver tank proceed

d. Add oil through filler plug opening until level is

as follows

at center of the compressor sight glass.

(1) Close discharge service valve fully

e. Crack suction service valve and purge

clockwise Remove cap from discharge service valve tee

compressor

(2) Open receiver outlet valve and let gas

f. Replace compressor filler plug

escape through discharge service port for 10 seconds

g. Fully open suction service valve and turn stem

Replace cap on port.

clockwise until suction pressure gauge registers.

(3) Open discharge service valve to normal

h. Fully open discharge service valve and then

position Open receiver outlet valve slightly and build

turn valve stem clockwise one- fourth of a turn

pressure to 3 to 5 pounds Check for leaks

Return unit to normal operation.

(4) Reset valves on unit for normal operation

6-5.1

Discharging Refrigeration System.

6-7. Detecting Moisture.

NOTE

Excessive water vapor may enter the refrigeration

In accordance with Environmental

system At the low temperatures developed in the system,

Protection

Agency

regulations,

this vapor condenses and may freeze the expansion

refrigerants can-not be discharged into

valve in an open or closed position The operating

the atmosphere A refrigerant recovery

characteristics of a unit with a frozen expansion valve are

& recycling unit must be used

given below

whenever discharging the refrigerant

a Valve Frozen Shut If expansion valve is frozen

system

Operation

the

shut, the following operating characteristics may be

recovery/recycling unit must be by

observed

AUTHORIZED PERSONNEL ONLY

(1) Unit

operates

continuously,

box

temperature remains high

Connect and operate a recovery/recycling unit In

(2) Suction pressure remains abnormally low

accordance with the manufacturer's instructions.

Chance 5 6-2