Carrier 69NT20-531-300 manual Condenser FAN and Motor Assembly

6.10.2 Checking High Pressure Switch

WARNING

Do not use a nitrogen cylinder without a pressure regulator. Do not use oxygen in or near a refrigeration system as an explosion may occur.

NOTE

The high pressure switch is non-adjustable.

a. Remove switch as outlined in paragraph 6.10.1

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 6-9.)

c. Unsolder discharge line and remove the line to the receiver or water-cooled condenser.

d. Remove coil mounting hardware and remove the coil.

e. Install replacement coil and solder connections.

f.Leak-check the coil connections per paragraph para- graph 6.5. Evacuate the unit per paragraph 6.6 then charge the unit with refrigerant per paragraph 6.7.

6.12 CONDENSER FAN AND MOTOR ASSEMBLY

WARNING

Do not open condenser fan grille before turning power OFF and disconnecting power plug.

The condenser fan rotates counter-clockwise (viewed from front of unit), pulls air through the the condenser coil, and discharges horizontally through the front of the unit. To replace motor assembly:

1

2

3

4

5

6

1.Cylinder Valve and Gauge

2.Pressure Regulator

3.Nitrogen Cylinder

4.Pressure Gauge (0 to 36 kg/cm@ = 0 to 400 psig)

5.Bleed-Off Valve

6.1/4 inch Connection

a. Open condenser fan screen guard.

b. Loosen two square head set screws on fan. (Thread sealer has been applied to set screws at installation.) Disconnect wiring from motor junction box.

CAUTION

Take necessary steps (place plywood over coil or use sling on motor) to prevent motor from falling into condenser coil.

Figure 6-9 High Pressure Switch Testing

d. Set nitrogen pressure regulator at 26.4 kg/cm@ (375 psig) with bleed-off valve closed.

e. Close valve on cylinder and open bleed-off valve.

f.Open cylinder valve. Slowly close bleed-off valve to increase pressure on switch. The switch should open at a static pressure up to 25 kg/cm@ (350 psig). If a light is used, light will go out. If an ohmmeter is used, the meter will indicate open circuit.

g.Slowly open bleed-off valve to decrease the pressure. The switch should close at 18 kg/cm@ (250 psig).

6.11 CONDENSER COIL

The condenser consists of a series of parallel copper tubes expanded into copper fins. The condenser coil must be cleaned with fresh water or steam so the air flow is not restricted. To replace the coil, do the following:

WARNING

Do not open the condenser fan grille before turning power OFF and disconnecting power plug.

a. Using a refrigerant reclaim system, remove the refrigerant charge.

b. Remove the condenser coil guard.

c. Remove motor mounting hardware and replace the motor. It is recommended that new locknuts be used when replacing motor. Connect wiring per wiring diagram.

d. Install fan loosely on motor shaft (hub side in). DO NOT USE FORCE. If necessary, tap the hub only, not the hub nuts or bolts. Install venturi. Apply “Loctite H” to fan set screws. Adjust fan within venturi so that the outer edge of the fan is within 2.0 ± .07 mm (0.08” ¦ 0.03”) from the outside of the orifice open- ing. Spin fan by hand to check clearance.

e. Close and secure condenser fan screen guard.

f. Apply power to unit and check fan rotation. If fan motor rotates backward, reverse wire numbers 5 and 8.

6.13 FILTER-DRIER

On units equipped with a water-cooled condenser, if the sight glass appears to be flashing or bubbles are constantly moving through the sight glass when the suction modulation valve is fully open, the unit may have a low refrigerant charge or the filter-drier could be partially plugged.

a. To Check Filter-Drier

1.Test for a restricted or plugged filter-drier by feeling the liquid line inlet and outlet connections of the drier cartridge. If the outlet side feels cooler than the inlet side, then the filter-drier should be changed.

T-309 6-8