Page 48
506212−01 11/10
POWER DEFROST MODE
K1
K2
K2
K3
K4
Operation Mode
ComfortSense®
Gas Furnace
Dedicated Heat Pump (XPG15)
INPUTS/OUT-
PUTS
"
Y1
W1
W2
O
G
E
L
Y1
Y2
W1
W2
G
O
Y1
W
IN
RL/
K229
O
Y1
OUT
W
OUT
Defrost Mode
Power Defrost
X
X
X
X
X
X
X
DEMAND DEFROST CONTROL INTERNAL RELAY CONTACT STATUS
1. K1 relay contact open to cycle OFF outdoor fan.
2. K2 relay contact close and output 24VAC to
RL
output to energize K229 field installed relay.
3. K2 relay contact close and energize reversing valve.
4. K3 relay contact close and energize compressor contactor.
5. K4 relay contact remain open.
6. K229 relay with normally closed contacts is now open and removes the
Y1
and
G
signals going from the room
thermostat to the furnace control. Indoor blower will cycle OFF.
DEFROST TERMINATION
Once a power defrost mode has been initiated, the next event will occur as explained on page 40.