Lennox A98USMV Installation Instructions Manual page 71

Troubleshooting: Cooling Sequence of Operation
508364-01
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.
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
Issue 2346
NO
Page 71 of 74