11
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.
NOTE
: Crankcase heaters are only available on 38HDR030--060
units.
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.
Service Valves
The service valves in the outdoor unit come from the factory
frontseated. This means the refrigerant charge is isolated from the
line--set connection ports. To prevent damage to the valve, use a
wet cloth or other accepted heat sink material on the valve before
brazing.
The service valve cannot be field repaired, therefore, only a
complete valve or valve stem seal and service port caps are
available for replacement.
Refrigerant Charging
!
WARNING
PERSONAL INJURY AND/OR EQUIPMENT
DAMAGE HAZARD
Failure to follow this warning could result in personal
injury and/or equipment damage.
Wear safety glasses and gloves when handling
refrigerant. Do not overcharge system -- this can cause
compressor flooding.
!
WARNING
PERSONAL INJURY AND/OR EQUIPMENT
DAMAGE HAZARD
Failure to follow this warning could result in personal
injury and/or equipment damage.
Service valves must be fully backseated to close service
port. There is no Schrader valve at the service port, and
failure to backseat the valve could result in loss of
system charge or personal injury.
NOTE
:
Do not vent or de--pressurize unit refrigerant to
atmosphere. Remove and recover refrigerant following accepted
practices.
All units are shipped with the refrigerant charge listed on the
nameplate.
Refer to Table 3 and consider the following when working with
Puron
r
refrigerant:
S
Puron refrigerant cylinders are rose colored.
S
Recovery cylinder service pressure rating must be 400
psig, DOT (Department of Transportation) 4BA400 or
DOT BW400.
S
Puron systems should be charged with liquid refrigerant.
Use a commercial type metering device in the manifold
hose when charging into suction line with compressor op-
erating.
S
Manifold sets should be 700 psig high side and 180 psig
low side with 550 psig low--side retard.
S
Use hoses with 700 psig service pressure rating.
S
Puron refrigerant, as with other HFCs, is only compatible
with POE oils.
S
Vacuum pumps will not remove moisture from oil.
S
Polyol Ester oils absorb moisture rapidly. Do not expose
oil to atmosphere.
S
Polyol Ester oils may cause damage to certain plastics and
roofing materials.
S
Wrap all filter driers and service valves with wet cloth when
brazing.
S
Factory approved, liquid--line filter drier is required on ev-
ery unit.
S
Do not use a TXV (thermostatic expansion valve) de-
signed for use with R--22 refrigerant. Refer to separate in-
door unit installation instructions for more details.
S
If using a suction line drier, do not leave in place for more
than 72 hours.
38H
D
R
