Comfort Alert Diagnostic Module - Carrier Gemini 38AU Series Installation, Start-Up And Service Instructions Manual

of the check valve core without having to recover the entire sys-
tem refrigerant charge. Apply compressor refrigerant oil to the
check valve core's bottom o-ring. Install the fitting body with 96
±10 in.-lbs (1085 ±23 N-cm) of torque; do not overtighten.
SEAT
.47
5/8" HEX
CORE
(Part No. EC39EZ067)
WASHER
O-RING
1/2" HEX
This surface provides a metal to metal seal when
torqued into the seat. Appropriate handling is
required to not scratch or dent the surface.
Fig. 36 — CoreMax
HOT GAS BYPASS VALVE ADJUSTMENTS
Refer to Fig. 30 for a unit piping schematic with factory option
Hot Gas Bypass control.
The suction pressure regulating valve is located between the
unit's compressor discharge line and the desuperheating tank. A
suction pressure tube is connected between the regulating valves
and the unit suction line. This valve is factory set to begin to
open as suction pressure drops below 109 psig (752 kPa). This
valve can be adjusted by removing the cover bolt on the valve to
expose the Allen key socket. One turn of this stem provides a 5
psig (34 kPa) change in valve opening setting. CW turn reduces
the opening setting. CCW turn increases the opening setting.
MAXIMUM CCW adjustment is one turn.
The factory setting is designed to provide a longer run time
during first stage cooling operation by beginning to open at ap-
proximately 36°F (2°C) evaporator saturated suction tempera-
ture as space load approaches satisfaction. This extended run
time will provide additional dehumidification effect.

Comfort Alert Diagnostic Module

The Comfort Alert Diagnostic Module (CADM) monitors and an-
alyzes data from the Copeland Scroll three-phase compressor and
the thermostat demand. The CADM also provides a 3-minute anti-
recycle time delay to compressor cycling. Each compressor has a
separate CADM module.
The CADM detects causes for electrical and system related fail-
ures without any sensors. Flashing LEDs communicate the Alert
codes to guide service technicians in accurately and quickly trou-
bleshooting the system and determining root cause for the failure.
Inputs to the CADM include 24-vac power, thermostat Y1 or
Y2, compressor contactor coil (common side) and compressor
power leads (from the compressor contactor). See Table 19.
1. CoreMax is a registered trademark of Fastest, Inc.
1/2-20 UNF RH
0.596
30°
45°
DEPRESSOR PER ARI 720
+.01/-.035
FROM FACE OF BODY
7/16-20 UNF RH
1 Access Port Assembly
Table 19 — Comfort Alert Diagnostic Module Inputs
INPUT
Control Power
Demand*
Control Common
Cooling
Contractor Coil
Line A
Line B
Line C
* Only applies to 38AUZ(D,E).
Control of the compressor contactor coil is through a normally-
closed (power on the module) contact between terminals P and C.
Communications of status and alert conditions is through three
LEDs located on the top edge of the module housing (see
Fig. 37): POWER (green), ALERT (yellow), and TRIP (red).
The POWER LED indicates the presence of control power to the
CADM.
The ALERT LED indicates an abnormal condition exists in the
system through a flash code. The ALERT LED will blink a num-
ber of times consecutively, pause and the repeat the process. The
number of blinks, defined in Table 20, correlates to a particular ab-
normal condition; troubleshooting tips are provided for each Alert
code. Reset of the ALERT may be automatic or manual. If the
fault condition causing the Alert is self-corrected, the Alert code
will be removed and the CADM will automatically reset and al-
low the system to restart normally. Manual reset requires that main
power to the 38AU unit be recycled after the cause for the Alert
condition has been detected and corrected.
POWER
(GRN)
POWER
ALERT
(YEL)
ALERT
TRIP
TRIP
(RED)
Fig. 37 — CADM Housing/LED Locations
The TRIP LED indicates either a time-delay period is currently
active (RED LED is blinking) or the module has locked out the
compressor (RED LED is on steady). A lockout condition will oc-
cur when the CADM detects a thermostat demand at input Y but
there is no power at the compressor line terminals T1 or T2 or T3.
This lockout can occur due to a safety switch (LPS or HPS) open-
ing and de-energizing the compressor contactor, the compressor-
motor internal overload opens, or other internal power interruption
has occurred. Reset of the TRIP LED requires that unit main pow-
er be recycled after the loss of power to the compressor condition
has been detected and corrected.
Simultaneous blinking of YELLOW and RED LEDs indicates
control power input to the CADM is low. Check control circuit
transformer and wiring.
TROUBLESHOOTING THE CADM WIRING
Flashing LEDs also indicate wiring problems to the CADM. See
Tables 20 and 21 for discussion of additional LED flash codes and
troubleshooting instructions.
33
TERMINAL VOLTAGE
R 24-v
Y2 24-v
C 24-v
Y 24-v
P 24-v
T1 Line
T2 Line
T3 Line
Comfort Alert
™
Commercial Diagnostics
Green LED - 24VAC Power
Yellow LED - Flash Code
2 System Pressure Trip
3 Short Cycling
4 Locked Rotor
5 Open Circuit
T1
6 Missing Phase
7 Reverse Phase
8 Welded Contactor
9 Low Voltage
Red LED - Protector Open
or no compressor power
T2
Active Protection
PROT breaks 24VAC common
leg of compressor contactor coil
Reset codes and PROT lockout
by removing 24VAC to module
For Two-Stage Applications:
T3
DC SOL operating range: 4-18VAC
Compressor second stage is
energized when YA & Y2 are 24VAC
and Alert and Trip LEDs are off
EMERSON ™
Climate Technologies