Lennox LCH036 Installation Instructions Manual page 38

Cooling Operation - 036, 048, 060
This is a summary of cooling operation. Refer to the
sequence of operation provided in the Engineering
Handbook or Service Manual for more detail.
Note - During a dehumidification demand the blower
operates at the highest speed. Free cooling is locked-out
during reheat operation. Refer to hot gas reheat start-up
and operation section for details.
A-Two-Stage Thermostat
1-Economizer With Outdoor Air Suitable
Y1 Demand -
Compressors Off
Blower Cooling Low
Dampers modulate
Y2 Demand -
Compressors Off
Blower Cooling High
Dampers Modulate
Note - If dampers are at maximum open for three
minutes, compressor is energized at high speed and
blower stays on cooling high.
2-No Economizer or Outdoor Air Not Suitable
Y1 Demand -
Compressor Low
Blower Cooling Low
Dampers Minimum Position
Y2 Demand -
Compressor High
Blower Cooling High
Dampers Minimum Position
B-Three-Stage Thermostat OR Room Sensor
1-Economizer With Outdoor Air Suitable
Y1 Demand -
Compressors Off
Blower Cooling Low
Dampers modulate
Y2 Demand -
Compressors Off
Blower Cooling High
Dampers Modulate
Note - If dampers are at maximum open for three minutes,
compressor 1 is energized and blower stays on cooling high.
Y3 Demand -
Compressors 1 and 2 On
Blower Cooling High
Dampers Maximum Open
Cooling Operation - 072
This is a summary of cooling operation. Refer to the
sequence of operation provided in the Engineering
Handbook or Service Manual for more detail.
Note - During a dehumidification demand the blower
operates at the highest speed. Free cooling is locked-out
during reheat operation. Refer to hot gas reheat start-up
and operation section for details.
A-Two-Stage Thermostat
1-Economizer With Outdoor Air Suitable
Y1 Demand -
Compressors Off
Blower Cooling On
Dampers modulate
Note - If dampers are at maximum open for three
minutes, compressor is energized.
Y2 Demand -
Compressors On
Blower Cooling On
Dampers Modulate
2-No Economizer or Outdoor Air Not Suitable
Y1 Demand -
Compressor 1 On
Blower Cooling On
Dampers Minimum Position
Page 38
LGH/LCH036, 048, 060, 072