Troubleshooting: Cooling Sequence Of Operation - Lennox G71MPP Installation Instructions Manual

Troubleshooting: Cooling Sequence of Operation

CALL FOR COOLING
5
1st Stage Cooling
Request Received
Energize 1st Stage
Cooling Contactor
(Compressor & Fan)
Indoor Blower On
After 2−second delay
Energize Indoor Blower
(Per Ramping Profile)
1
2nd Stage
Cooling
Request?
YES YES
Energize 2nd Stage
Energize Indoor Blower
Cooling Contactor
(High Cooling mode)
(Compressor & Fan)
2nd Stage
Cooling Request
Still Active?
NO
De−Energize 2nd
Stage Cooling
Contactor
(Compressor & Fan)
1st Stage
Cooling Request
Still Active?
NO
De−Energize 1st
Stage Cooling
Contactor
(Compressor & Fan)
De−Energize Indoor Blower
Per Ramping Profile
2nd stage cooling operation requires a 2−stage thermostat, a 2−stage cooling system and
1
on−board link W915 must be be cut. The control will not respond to a 2nd stage cooling
request unless a 1st stage cooling request is active
Indoor blower cooling mode and high cooling mode have a specific ON, OFF and speed
2
ramping profiles. The specific profile is selected using the DIP switches on the control.
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1
2
YES
1st Stage
NO Cooling Request
Still Active?
2
Maintain Indoor Blower
YES
(High Cooling mode)
Energize and
Maintain Indoor Blower at
YES
Low Cooling mode
2
NO