Carrier 38AUD*12 Series, Installation, Start-Up And Service Instructions Manual, Page: 68 / 80

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Table 10 – 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 re-
ceive its power from another device that will interrupt the 24VAC
power supply. See the 38AUD Wiring Diagrams (Fig. 18 and
Fig. 19).
Green LED Intermittent,
module powers up only
when compressor runs
Determine if R and Y terminals are wired in reverse. Verify mod-
ule’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 38AUD wiring dia-
gram (see Fig. 18 and Fig. 19). Verify voltage at contactor coil
falls below 0.5VAC when off. Verify 24VAQC 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 *
(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.
Crankcase Heater — The heater prevents refrigerant
migration and compressor oil dilution during shutdown
whenever compressor is not operating. The heater is wired
to cycle with the compressor; the heater is off when
compressor is running, and on when compressor is off.
The crankcase heater will operate as long as the power
circuit is energized.
Compressor Protection
COMPRESSOR OVERTEMPERATURE 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 main
disconnect must be on to energize the crankcase heater.
IMPORTANT: Never open any switch or disconnect
that energizes the crankcase heater unless unit is
being serviced or is to be shut down for a prolonged
period. After a prolonged shutdown on a service job,
energize the crankcase heater for 24 hours before
starting the compressor.
ADVANCED SCROLL TEMPERATURE PROTECTION
(ASTP) — See “Advanced Scroll Temperature Protection
(ASTP)” on page 18.
Low-Pressure Switch —
The 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.
Lubrication
FAN MOTORS have sealed bearings. No provisions are
made for lubrication.
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 system has been in operation.
38A
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