Note: 24VAC power wiring is not required for 2 wire Comfort Alert, which is
powered by the demand (Y terminal). Even if the 24VAC power supply is
available it should not be connected. Refer to Figure 7.
Thermostat Demand Wiring
Comfort Alert 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 24VAC. When thermostat demand is not present, Y should be less than 0.5VAC.
NOTE: Factory installed modules may have different thermostat demand signal
wiring. Follow manufacturer's wiring instructions when replacing
module.
NOTE: After the thermostat demand signal is connected, verify R and C are
phased properly by measuring 24VAC across Y and C when demand is
present (except 543-0010-01, 943-0010-01).
Figure 6: Air Conditioning Schematic 543-0010-00, 943-0010-00
Solid Line shows field
installed wiring.
Dashed line shows thermostat
demand wiring in system without
HTCO, LPCO.
Comfort Alert
Diagnostics Module
Y
543-0010-00
R
C
HTCO High Temperature Cut Out Switch
HPCO High Pressure Cutout Switch
LPCO Low Pressure Cut Out Switch
LPCO
HPCO
C
Indoor Unit
Terminal Block
C
Schematic Abbreviation Description
CC Compressor Contactor
5
HTCO
R
Y1
R
Y1
Single Stage Indoor Thermostat
