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6.9 HIGH PRESSURE SWITCH
6.9.1 Checking High Pressure Switch
WARNING
Do not use a nitrogen cylinder without a
pressure regulator.
NOTE
The high pressure switch is non-adjustable.
a. Remove switch as outlined in paragraph 6.9.2
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
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
2
=
0 to 400 psig)
5. Bleed-Off Valve
6. 1/4 inch Connection
Figure 6-15 High Pressure Switch Testing
d. Set nitrogen pressure regulator at 26.4kg/cm
(375psig) 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 25kg/cm
(350psig). 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 pres-
sure. The switch should close at 18kg/cm
(250psig).
6.9.2 Replacing High Pressure Switch
a. Turn unit start-stop switch OFF. Frontseat both suc-
tion and discharge service valves to isolate compres-
sor. Remove the refrigerant from the compressor.
b. Disconnect wiring from defective switch. The high
pressure switch is located on the center head and is
removed by turning counterclockwise (see
c. Install a new high pressure switch after verifying
switch settings (refer to paragraph 6.9.1).
d. Evacuate and dehydrate the compressor per
paragraph 6.6.
6.10 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 refrig-
erant charge.
b. Remove the condenser coil guard.
c. Unsolder lines 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.
6.11 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 condenser coil
and discharges horizontally through the front of the unit.
To replace motor assembly:
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).
c. 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.
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Страница 131: ...7 3 T 318 Based on Drawing 62 66058 Figure 7 2 SCHEMATIC DIAGRAM Units with 3 Phase Evaporator Motors...
Страница 133: ...7 5 T 318 6 Heater FCCH FCCH Figure 7 4 SCHEMATIC DIAGRAM Units with Normal Evaporator Fan Capability...
Страница 134: ...7 6 T 318 FCCH FCCH Figure 7 5 SCHEMATIC DIAGRAM Units with Single Evaporator Fan Capability...
Страница 136: ...7 8 T 318 To ST10 To TRX2 To QC1 To QC1 To QC1 To MC6 CONTROLLER Figure 7 7 SCHEMATIC DIAGRAM Emergency Bypass...
Страница 138: ...7 10 T 318 Based on Drawing 62 66058 Figure 7 9 UNIT WIRING DIAGRAM Units with 3 Phase Evaporator Motors Sheet 1 of 2...
Страница 139: ...7 11 T 318 Based on Drawing 62 66058 Figure 7 10 UNIT WIRING DIAGRAM Units with 3 Phase Evaporator Motors Sheet 2 of 2...
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