Page 21
31-5000724 Rev. 0
Operating Sequence
System Demand
System Response
System
Condition
Step
Thermostat Demand
Relative Humidity
Compressor
Blower
CFM
(COOL)
Comments
1st
Stage
2nd
Stage
O
G
Status
D
NO CALL FOR DEHUMIDIFICATION
Normal Operation
- Y1
1
On
On
On
Acceptable
24
VAC
Low
70%
Compressor and indoor
blower follow thermostat
demand
Normal Operation
- Y2
2
On
On
On
On
Acceptable
24
VAC
High
100%
ROOM THERMOSTAT CALLS FOR FIRST STAGE COOLING
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24
VAC
Low
70%
Thermostat energizes
2nd Stage and de-
energizes D on a call for
de-humidification
Dehumidification
Call
2
On
On
On
On
Demand
0
VAC
High
70%
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24
VAC
Low
70%
Dehumidification mode
begins when humidity is
greater than set point.
Maximum overcool from
cooling setpoint is 2°F.
Dehumidification
Call
2
On
On
On
On
Demand
0
VAC
High
70%
Dehumidification
Call ONLY
1
On
On
On
On
Demand
0
VAC
High
70%
Thermostat will keep
outdoor unit energized
after cooling temperature
setpoint has been
reached in order to
maintain room humidity
setpoint. Maximum
overcool from cooling
setpoint is 2°F.
ROOM THERMOSTAT CALLS FOR FIRST AND SECOND STAGE COOLING
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
On
On
On
Acceptable
24
VAC
High
100%
Thermostat energizes
2nd Stage and de-
energizes D on a call for
de-humidification
Dehumidification
Call
2
On
On
On
On
Demand
0
VAC
High
70%
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24
VAC
Low
70%*\
Dehumidification mode
begins when humidity is
greater than set point.
Maximum overcool from
cooling setpoint is 2°F.
Dehumidification
Call
2
On
On
On
On
Demand
0
VAC
High
70%
Dehumidification
Call ONLY
1
On
On
On
On
Demand
0
VAC
High
70%
Thermostat will keep
outdoor unit energized
after cooling temperature
setpoint has been
reached in order to
maintain room humidity
setpoint. Maximum
overcool from cooling
setpoint is 2°F.
•
On-board links at indoor unit with a two stage outdoor unit
•
Cut factory link from Y1 to Y2 or cut W915 (Y1 to Y2) on integrated control
•
With Condensing unit - Cut W914 (R to OS) on integrated control
•
With Heat Pump - Cut W914 (R to DS) and W951 (R to O) on integrated control
Table 14. Cooling Operating Sequence
NF97DM and Two Stage Outdoor Unit
