36
Compressor Protection
COMPRESSOR OVER-TEMPERATURE PROTECTION (IP)
A thermostat installed on the compressor motor winding reacts
to excessively high winding temperatures and shuts off the
compressor.
CRANKCASE HEATER
The heater minimizes absorption of liquid refrigerant by oil in the
crankcase during brief or extended shutdown periods. The heater
is wired to cycle with the compressor; the heater is off when com-
pressor is running, and on when compressor is off.
The crankcase heater will operate as long as the power circuit is
energized. The main disconnect must be on to energize the crank-
case heater.
ADVANCED SCROLL TEMPERATURE PROTECTION
(ASTP)
See “Advanced Scroll Temperature Protection (ASTP)” on
page 20.
LOW-PRESSURE SWITCH
The 38AU low-pressure switch is stem-mounted on the suction
line. Switches are all fixed, non-adjustable type.
HIGH-PRESSURE SWITCH
The high-pressure switch is stem mounted on the discharge line.
The switch is a fixed, non-adjustable type.
OUTDOOR FANS
Each fan is supported by a formed-wire mount bolted to the fan
deck and covered with a wire guard. Fan motors have permanently
lubricated bearings.
1. Shut off unit power supply. Install lockout tag.
2. Remove outdoor fan assembly (grille, motor, and fan).
3. Loosen fan hub setscrews.
4. Adjust fan height as shown in Fig. 38.
5. Tighten setscrews to 84 in.-lb (949 N-cm).
6. Replace outdoor fan assembly.
Fig. 38 — Outdoor Fan Blade Position
LUBRICATION
Fan Motors
The fan motors have sealed bearings. No provisions are made for
lubrication.
Compressor
The compressor has its own oil supply. Loss of oil due to a leak in
the system should be the only reason for adding oil after the sys-
tem has been in operation.
Routine Cleaning of Round-Tube Plate Fin
(RTPF) Coils
Periodic cleaning with Totaline
®
environmentally balanced coil
cleaner is essential to extend the life of RTPF coils. This cleaner is
available from Carrier Replacement parts division as part number
P902-0301 for a one gallon container, and part number P902-0305
for a 5 gallon container. It is recommended that all RTPF coils be
cleaned with the Totaline environmentally balanced coil cleaner as
described below.
Coil cleaning should be part of the unit’s regularly scheduled
maintenance procedures to ensure long life of the coil. Failure to
clean the coils may result in reduced durability in the environment.
Avoid the use of:
• coil brighteners
• acid cleaning prior to painting
• high pressure washers
• poor quality water for cleaning
Totaline environmentally sound coil cleaner is non-flammable,
hypoallergenic, non-bacterial, and a USDA accepted biodegrad-
able agent that will not harm the coil or surrounding components
such as electrical wiring, painted metal surfaces, or insulation. Use
of non-recommended coil cleaners is strongly discouraged since
coil and unit durability could be affected.
Table 20 — CADM Troubleshooting
MISWIRED MODULE INDICATION RECOMMENDED TROUBLESHOOTING ACTION
Green LED is not on,
module does not power up
Determine if both R and C module terminals are connected. Verify voltage in present at module’s R and C
terminals.
NOTE: The CADM requires a constant nominal 24VAC power supply. The wiring to the module’s R and C
terminals must be directly from the control transformer. The module cannot receive its power from another
device that will interrupt the 24VAC power supply. See Appendix B Wiring Diagrams.
Green LED Intermittent,
module powers up only
when compressor runs
Determine if R and Y terminals are wired in reverse. Verify module’s R and C terminals have a constant
source. See “NOTE” above for details on R and C wiring.
TRIP LED is on but system
and compressor check OK
Verify Y terminal is wired properly per the 38AU wiring diagram (see Appendix B Wiring Diagrams). Verify
voltage at contactor coil falls below 0.5VAC when off. Verify 24VAC is present across Y and C when
thermostat demand signal is present. If not, R and C are reverse wired.
TRIP LED and ALERT LED
flashing together
Verify R and C terminals are supplied with 19-28VAC.
ALERT Flash Code 3
(Compressor Short Cycling)
displayed incorrectly
Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at contactor coil falls below
0.5VAC when off.
ALERT Flash Code 5 or 6
(Open Circuit, Missing Phase)
displayed incorrectly
Check that compressor T1 and T3 wires are through module’s current sensing holes. Verify Y terminal is
connected to 24VAC at contactor coil. Verify voltage at contactor coil falls below 0.5VAC when off.
Alert Flash Code 8
(Welded Contactor)
displayed incorrectly
Determine if module’s Y terminal is connected. Verify Y terminal is connected to 24VAC at contactor coil.
Verify 24VAC is present across Y and C when thermostat demand signal is present. If not, R and C are
reverse wired. Verify voltage at contactor coil falls below 0.5VAC when off.
IMPORTANT: Never open any switch or disconnect that ener-
gizes the crankcase heater unless unit is being serviced or is to
be shut down for a prolonged period. After a prolonged shut-
down on a service job, energize the crankcase heater for 24
hours before starting the compressor.
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