5
SERVICE
!
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF position.
There may be more than 1 disconnect switch. Lock out and
tag switch with a suitable warning label.
Outdoor Fan
A reinforced wire mount holds the outdoor fan assembly in
position. See Fig. 7 for proper mounting position.
538B Unit Size, in. (mm)
018,024
030,036
048,060
0.433 (11.00)
0
0
A07401
Fig. 7
---
Condenser Fan Mounting Positions
High--Pressure Relief Valve
The high--pressure relief valve is located in the compressor. The
relief valve opens at a pressure differential of approximately 550 to
625
±
50 psig between suction (low side) and discharge (high side)
to allow pressure equalization.
Internal Current and Temperature Sensitive Overload
The control resets automatically when internal compressor motor
temperature drops to a safe level (overloads may require up to 45
minutes to reset). When an internal overload is suspected of being
open, check by using an ohmmeter or continuity tester.
Pumpdown Procedure
The system may be pumped down in order to make repairs on the
low side without losing complete refrigerant charge.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Never open system to atmosphere while it is under a vacuum.
When system must be opened for service, recover refrigerant, break
vacuum with dry nitrogen before opening system.
1. Attach pressure gage to suction service valve gage port.
2. Frontseat the liquid/mixed phase line valve.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
The unit coils hold only the factorydesignated amount of
refrigerant. Additional refrigerant may cause units to relieve
pressure through the compressor internal pressure relief
valve (indicated by a sudden rise of suction pressure) before
suction pressure reaches 20 psig. If this occurs, shut off unit
immediately then frontseat the suction valve and remove
and recover excess refrigerant following accepted practices
3. Start unit and run until suction pressure reaches 20 psig.
4. Shut unit off and frontseat suction valve.
5. De--pressurize low side of unit and recover refrigerant fol-
lowing accepted practices.
High--Pressure Switch
The high--pressure switch, located on discharge line, protects
against high discharge pressures caused by such events as
overcharge, condenser--fan motor failure, system restriction, etc. It
opens on pressure rise at about 650
±
10 psig. If system pressures
go above this setting during abnormal conditions, the switch
opens.
!
WARNING
PERSONAL INJURY HAZARD
Failure to follow this warning could result in personal
injury or death.
DO NOT
attempt to
simulate
these system
abnormalities -- high pressures pose a serious safety
hazard.
The high--pressure switch is checked with an ohmmeter. If system
pressure is below 625 psig switch shows continuity.
Crankcase Heater
The crankcase heater prevents refrigerant migration and
compressor oil dilution during shutdown when compressor is not
operating. If the crankcase heater is de--energized for more than 6
hours, both compressor service valves must be closed.
The crankcase heater is powered by the high--voltage power of the
unit. It is connected across the line side of the contactor and is
thermostatically controlled.
!
WARNING
PERSONAL INJURY HAZARD
Failure to follow this warning could result in personal injury
or death.
Use extreme caution when troubleshooting this device as
line voltage is continually present.
To troubleshoot:
1. Apply voltmeter across crankcase heater leads to see if heat-
er voltage is on. Do not touch heater. Carefully feel area
around crankcase heater; if warm, crankcase heater is func-
tioning.
2. With power off and heater leads disconnected, check across
leads with ohmmeter. Do not look for a specific resistance
reading. Check for resistance or an open circuit, and change
heater if an open circuit is detected.
538B
