Emerson 543-0033-02 - Installation Wiring - Thermostat Demand; Thermostat Demand Wiring

5
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
Dashed line shows thermostat
Comfort Alert
LPCO HTCO
HPCO
Indoor Unit
HTCO High T emperatu re Cut Out Switch
HPCO High Pressure Cutout Switch
LPCO Low Pressure Cut Out Switch
Schematic Abbreviation Description
CC Compr esso r Cont a ctor
Single Stage Indoor Thermostat
inst alled w iring.
demand wiring in system without
HTCO, LPCO.
Diagnostics Module
543-0010-00
Terminal Block
Y
R
C
CRY1
CRY1