Figure 7.15 High Pressure Switch Testing - Carrier 69NT40-541-505 Operation And Service Manual

Table of Contents

a. Checking the Oil Level in the Compressor

1. Turn unit on and operate in cooling mode for at

least 20 minutes.

2. Check the front oil sight glass on the compres-

sor to ensure that no foaming of the oil is pres-

ent after 20 minutes of operation. If the oil is

foaming excessively after 20 minutes of opera-

tion, check the refrigerant system for flood-back

of liquid refrigerant. Correct this situation before

performing step 3.

3. Turn unit off to check the oil level. The correct oil

level range should be between the bottom to

one-eighth level of the sight glass. If the level is

above one-eighth, oil must be removed from the

compressor. To remove oil from the compressor,

follow step d in this section. If the level is below

the bottom of the sight glass, add oil to the com-

pressor following step b below.

b. Adding Oil with Compressor in System

1. The recommended method is to add oil using an oil

pump at the oil fill valve (see item 10,

2. In an emergency where an oil pump is not avail-

able, oil may be drawn into the compressor

through the suction service valve.

Connect the suction connection of the

gauge manifold to compressor suction ser-

vice valve port and immerse the common

connection of the gauge manifold in a con-

tainer of refrigeration oil. Extreme care must

be taken to ensure the manifold common

connection remains immersed in oil at all

times. Otherwise air and moisture will be

drawn into compressor.

Crack the suction service valve and gauge

valve to vent a small amount of refrigerant

through the common connection and the oil

to purge the lines of air. Close the gauge

manifold valve.

With the unit running, frontseat the suction

service valve and induce a vacuum in the

compressor crankcase. SLOWLY crack the

suction gauge manifold valve and oil will

flow through the suction service valve into

the compressor. Add oil as necessary.

c. Adding Oil to Service Replacement Compressor

Service replacement compressors are shipped without

oil. If oil is present in crankcase, test the oil to ensure it

is the correct oil and that moisture level is acceptable.

When adding oil to a service replacement compressor

add three liters (6.3 pints) using an oil pump at the oil fill

valve (see item 10,

mended to allow for return of any oil that may be in the

refrigerant system. Install compressor and check oil level

after it is placed in operation (refer to

T-368

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Figure

7.5). This quantity is recom-

Section

7.8.6).

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d. Removing Oil from the Compressor

1. If the oil level is above one-eighth sight glass,

excess oil must be removed from the compressor.

2. Close (frontseat) suction service valve and

pump unit down to 0 to .1 bar (0 to 2 psig).

3. Turn the unit off.

4. Frontseat discharge service valve and remove

the remaining refrigerant.

5. Loosen the oil drain plug on the bottom plate of the

compressor and drain the proper amount of oil from

the compressor to obtain the correct level.

6. Tighten the oil drain plug.

7. Backseat the suction and discharge service

valves.

8. Repeat step a to ensure proper oil level.

7.9

HIGH PRESSURE SWITCH

7.9.1

Checking High Pressure Switch

7.5).

Do not use a nitrogen cylinder without a

pressure regulator.

The high pressure switch is non-adjustable.

a. Remove switch as outlined in

b. Connect ohmmeter or continuity light across switch

terminals. Ohm meter will indicate no resistance or

continuity light will be illuminated if the switch

closed after relieving compressor pressure.

c. Connect hose to a cylinder of dry nitrogen, see

Figure

7.15.