24 VAC Power Wiring
The diagnostic module requires a constant 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 module cannot
be powered by R and C terminals on the defrost board without
experiencing nuisance alerts.
Thermostat Demand Wiring
The diagnostic module requires a thermostat demand signal to
operate properly. The thermostat demand signal input, labeled Y
on the module, should always be connected to the compressor
contactor coil so that when the coil is energized, the demand
signal input is 24 VAC. When the coil is not energized, the
demand signal input should be less than 0.5 VAC.
Incorrectly Wired Module Troubleshooting
Incorrectly Wired Module Indication
Green LED is not on, module does not
Green LED intermittent, module powers up
only when the compressor runs.
Trip LED is on but the system and the
compressor check OK.
Trip LED and Alert LED are flashing together. Verify that the R and C terminals are connected. See "24 VAC Power Wiring" earlier in this
Alert Flash Code 3 (Compressor Short
Cycling) is displayed incorrectly.
Alert Flash Codes 5, 6 or 7 (Open Circuit,
Open Start Circuit or Open Run Circuit) are
Alert Flash Code 6 (Open Start Circuit) is
displayed for Code 7 (Open Run Circuit) or
Alert Flash Code 8 (Welded Contactor) is
Leaves and other large obstructions should be removed from
the heat pump surfaces without damaging the fin surface of
If you need further assistance, you can write to the below
address with any questions or concerns:
Home Cooling and Heating
14610 Breakers Drive
Jacksonville, FL 32258
Recommended Troubleshooting Action
Determine if both R and C module terminals are connected. See "24 VAC Power Wiring"
section for R and C wiring.
Determine if R and Y terminals are wired in reverse. See "24 VAC Power Wiring" earlier in
this section for R and C wiring.
Verify that the Y terminal is connected to the 24 VAC at the contactor coil.
section for R and C wiring.
Verify that the Y terminal is connect to the 24 VAC at the contactor coil.
Check that the compressor run and start wires are through the module's current sensing
holes. Verify that the Y terminal is connected to the 24 VAC at the contactor coil.
Check that the compressor run and start wires are routed through the correct module
Determine if the module's Y terminal is connected. Verify that the Y terminal is connected
to the 24 VAC at the contactor coil.
ASSISTANCE OR SERVICE
Incorrectly Wired Module Codes
Depending on the system configuration, some Alert flash codes
may not be active. The presence of safety switches affects how
the system alerts are displayed by the module.
Incorrectly wiring the diagnostic module will cause false LED
codes. The Incorrectly Wired Module Troubleshooting chart
describes LED operation when the module is incorrectly wired
and what troubleshooting action is required to correct the
Routinely clean or change the indoor air filter. Should the
indoor coil become dirty, thus restricting airflow, call a
qualified service person to clean the coil surface.
An annual inspection by a qualified person should be
performed to ensure continued high-quality performance.
Please include a daytime phone number in your correspondence.
To order accessories contact your Whirlpool
Home Cooling and