T-340
7–10
Figure 7.6 High Pressure Switch Testing
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
- - - - -
4. Set nitrogen pressure regulator at 26.4 kg/cm
2
(375 psig) with bleed-off valve closed.
5. Close valve on cylinder and open bleed-off valve.
6. 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
2
(350 psig). If a light is used, the light will go out. If an ohmmeter is used,
the meter will indicate open circuit.
7. Slowly open bleed-off valve to decrease the pressure. The switch should close at 18 kg/cm
2
(250 psig).
7.9.2
Replacing High Pressure Switch
1. Remove the refrigerant charge.
2. Disconnect wiring from defective switch. The high pressure switch is located on the discharge connection or
line and is removed by turning counterclockwise.
3. Install a new high pressure switch after verifying switch settings.
4. Evacuate, dehydrate and recharge the system.
5. Start the unit, verify refrigeration charge and oil level.
7.10 Condenser Coil
The condenser coil 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 the power plug.
1. Using a refrigerant reclaim system, remove the refrigerant charge.
2. Remove the condenser coil guard.
3. Unsolder the lines and remove the line to the receiver or water-cooled condenser.
4. Remove the coil mounting hardware and remove the coil from the unit.
5. Install the replacement coil and solder connections.
6. Leak-check the coil connections (see
).
7. Evacuate the unit then charge the unit with refrigerant.
