Lennox SL280UHNV Installation Instructions Manual page 56

Troubleshooting: Cooling Sequence of Operation
CALL FOR COOLING
1ST STAGE COOLING
REQUEST RECEIVED
WAIT FOR COMPRESSOR TIMED
OFF DELAY TO EXPIRE
ENERGIZE 1ST STAGE
COOLING CONTACTOR
(COMPRESSOR & FAN)
INDOOR BLOWER 2
SECOND ON DELAY
ENERGIZE INDOOR BLOWER
(LOW COOLING MODE)
ENERGIZE 2ND STAGE
COOLING CONTACTOR
(COMPRESSOR & FAN)
COOLING REQUEST
DE−ENERGIZE 2ND
(COMPRESSOR & FAN)
COOLING REQUEST
DE−ENERGIZE 1ST
(COMPRESSOR & FAN)
DE−ENERGIZE INDOOR
1
1
2
MAINTAIN INDOOR
BLOWER
(LOW COOLING MODE)
1
2ND STAGE
NO
COOLING
REQUEST?
YES YES
ENERGIZE INDOOR BLOWER
(HIGH COOLING MODE)
2ND STAGE
MAINTAIN INDOOR BLOWER
YES
(HIGH COOLING MODE)
STILL ACTIVE?
NO
STAGE COOLING
CONTACTOR
1ST STAGE
ENERGIZE AND MAINTAIN
YES
INDOOR BLOWER AT
STILL ACTIVE?
(LOW COOLING MODE)
NO
STAGE COOLING
CONTACTOR
1
CONTROL WILL NOT RESPOND TO A 2ND STAGE COOLING REQUEST UNLESS A 1ST STAGE
COOLING REQUEST IS ACTIVE.
INDOOR BLOWER LOW COOLING MODE AND HIGH COOLING MODE HAVE SPECIFIC ON, OFF
2
AND SPEED RAMPING PROFILES. THE SPECIFIC PROFILE IS SELECTED USING THE
2
BLOWER
DIP SWITCHES ON THE CONROL.
1
YES
YES
1ST STAGE
COOLING REQUEST
STILL ACTIVE?
2
NO
Page 56