Page 20 of 24
506468-01
Issue 1946
LED Status
Fault Description
Troubleshooting Information
ALERT
(Yellow)
Flash Code 4
Locked Rotor
1. Run capacitor has failed
2. Low line voltage (contact utility if voltage at disconnect is low)
• Check wiring connections
3. Excessive liquid refrigerant in compressor
4. Compressor bearing are seized
5. Measure compressor oil level
ALERT
(Yellow)
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
• Check compressor contactor wiring and connectors
• Check for compressor contactor failure (burned, pitted, or open)
• Check wiring and connectors between supply and compressor
• Check for low pilot voltage at compressor contactor coil
4. High pressure switch is open and requires manual reset
5. Open circuit in compressor supply wiring or connections
6. Unusually long compressor protector reset time due to extreme ambient temperature
7. Compressor windings are damaged
• Check compressor motor winding resistance
ALERT
(Yellow)
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
• Check wiring and connectors between supply and the compressor S terminal
3. Compressor start winding is damaged
• Check compressor motor winding resistance
ALERT
(Yellow)
Flash Code 7
Open Run Circuit
Current only in start circuit
1. Open circuit in compressor run wiring or connections
• Check wiring and connectors between supply and the compressor R terminal
2. Compressor run winding is damaged
• Check compressor motor winding resistance
ALERT
(Yellow)
Flash Code 8
Welded Contactor
Compressor always runs
1. Compressor contactor has failed closed
2. Thermostat demand signal not connected to module
ALERT
(Yellow)
Flash Code 9
Low Voltage
Control circuit less than 17VAC
1. Control circuit transformer is overloaded
2. Low line voltage (contact utility if voltage at disconnect is low)
• Check wiring conditions
Table 7. Diagnostic Module Codes
Mis-wired Module Troubleshooting
Mis-wired 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 is present at module’s R and C
terminals. Review 24VAC Power Wiring section on Page 19 for R and C wiring.
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.
Review 24VAC Power Wiring section on Page 19 for R and C wiring.
TRIP LED is on, but system and
compressor check OK.
Verify Y terminal is connected to 24VAC at contactor coil. Verify voltage at contactor coils falls below 0.5VAC
when off.
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, 6, or 7
(open circuit, open start circuit,
or open run circuit) displayed
incorrectly.
Check that compressor run and start 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 6 (open start
circuit) displayed for Code 7 (open
run circuit) or vice versa.
Check that compressor run and start wires are routed through the correct module sensing holes.
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
24 VAC is present across Y and C when the thermostat demand signal is present. If not, R and C are reverse
wired. Verify voltage at contactor coil falls below 0.5VAC when off. Review Thermostat Demand Wiring for Y and
C wiring.
Table 8. Mis-wired Module Troubleshooting
