High Pressure Switch; Replacing High Pressure Switch; Checking High Pressure Switch; 7.10 Condenser Coil - Carrier 69NT40-541-001 Operation And Service

7.9

HIGH PRESSURE SWITCH

7.9.1

Replacing High Pressure Switch

a. Turn unit start-stop switch OFF. Remove the refrigerant from the system.
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
d. Evacuate and dehydrate the compressor per
7.9.2

Checking High Pressure Switch

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.
a. Remove switch as outlined in
b. Connect ohmmeter or continuity light across switch terminals. Ohmmeter will indicate no resistance or con-
tinuity light will be illuminated if the switch closed after relieving compressor pressure.
c. Connect hose to a cylinder of dry nitrogen. (See
d. Set nitrogen pressure regulator at 26.4 kg/cm² (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/cm² (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 pres sure. The switch should close at 18 kg/cm² (250 psig).

7.10 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:
Do not open the condenser fan grille before turning power OFF and disconnecting power plug.
Figure
Section
WARNING
!
The high pressure switch is non-adjustable.
Section 7.9.1

Figure 7.16 High Pressure Switch Testing

1
4
5
2
3
6
WARNING
!
3.3)
7.6.
NOTE
Figure 7.16)
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
7–17
Section 7.9.2)
T-316