66901 / 035-20393-001 Rev. C (1204)
10
Unitary Products Group
Comfort Alert
TM
Diagnostics —
The Comfort Alert
TM
diagnostics
module facilitates troubleshooting heat pump and air conditioning sys-
tem failures. This Comfort Alert
TM
module is designed only for single-
phase systems with scroll compressors that have internal overload pro-
tection. By monitoring and analyzing data from the compressor and the
thermostat demand, the module can detect the cause of electrical and
system related failures without any sensors. A flashing LED indicator
communicates the ALERT code and guides the service technician more
quickly and accurately to the root cause of a problem.
NOTE:
This module does not provide safety protection! The Comfort
Alert
TM
module is a monitoring device and cannot control or shut down
other devices.
LED Description (See Table 1)
POWER LED (Green):
indicates voltage is present at the power con-
nection of the module. ALERT LED (Yellow): communicates an abnor-
mal system condition through a unique flash code. The ALERT LED will
flash a number of times consecutively, pause and then repeat the pro-
cess. The number of consecutive flashes, defined as the Flash Code,
correlates to a particular abnormal condition. Detailed descriptions of
specific ALERT Flash Codes are shown in Table 6 of this manual.
TRIP LED (Red):
indicates there is a demand signal from the thermo-
stat but no current to the compressor is detected by the module. The
TRIP LED typically indicates the compressor protector is open or may
indicate missing supply power to the compressor.
The scroll compressor’s run (R), common (C) and start (S) wires are
routed through the holes in the Comfort Alert
TM
module marked “R,” “C”
and “S.”
24 VAC Power Wiring —
The Comfort Alert
TM
module requires a con-
stant nominal 24 VAC power supply. The wiring to the module’s R and C
terminals must be directly from the indoor unit or thermostat.
The Comfort Alert
TM
module requires a thermostat demand signal to
operate properly.
NOTE:
After the thermostat demand signal is connected, verify that 24
VAC across Y and C
when demand is present
.
TABLE 6:
Diagnostic Label
Status LED
Status LED Description
Status LED Troubleshooting Information
Green “POWER”
Module has power
Supply voltage is present at module terminals
Red “TRIP”
Thermostat demand signal Y1 is present,
but the compressor is not running
1. Compressor protector is open
2. Outdoor unit power disconnect is open
3. Compressor circuit breaker or fuse(s) is open
4. Broken wire or connector is not making contact
5. Low pressure switch is open
6. Compressor contactor has failed open
Yellow “ALERT”
Flash Code 2
System Pressure Trip
Low pressure switch fault
1. Low refrigerant charge
2. Evaportor blower is not running
3. Evaportor coil is frozen
4. Faulty metering device
5. Condenser coil is dirty
6. Liquid line restriction (filter drier blocked if present in system)
Yellow “ALERT”
Flash Code 3
Short Cycling
Compressor is running only briefly
1. High pressure switch fault
2. Condenser coil poor air circulation (dirty, blocked, damaged)
3. Condenser fan is not running
4. Return air duct has substantial leakage
5. Thermstat demand signal is intermittent
Yellow “ALERT”
Flash Code 4
Locked Rotor
1. Run capacitor has failed
2. Low line voltage (contact utility if voltage at disconnect is low)
3. Excessive liquid refrigerant in compressor
4. Compressor bearings are seized
Yellow “ALERT”
Flash Code 5
Open Circuit
1. Outdoor unit power disconnect is open
2. Compressor circuit breaker or fuse(s) is open
3. Compressor contactor has failed open
4. Low pressure switch is open
5. Open circuit in compressor supply wiring or connections
6. Unusually long compressor protector reset time due to exteme ambient
termperature
7. Compressor windings are damaged
Yellow “ALERT”
Flash Code 6
Open Start Circuit
Current only in run circuit
1. Run capacitor has failed
2. Open circuit in compressor start wiring or connections
3. Compressor start winding is damaged
Yellow “ALERT”
Flash Code 7
Open Run Circuit
Current only in start circuit
1. Open circuit in compressor run wiring or connections
2. Compressor run winding is damaged
Yellow “ALERT”
Flash Code 8
Welded Contactor
Compressor always runs
1. Compressor contactor has failed closed
2. Thermostat demand signal not connected to module
Yellow “ALERT”
Flash Code 9
Low Voltage
Control circuit < 17 VAC
1. Control circuit transformer is overloaded
2. Low line voltage (contact utility if voltage at disconnect is low)
