V" Blower And Vsp1 Blower Control Board; Heating Mode Checkout - Lennox G21Q3-40 Unit Information

YES
VSP1
1
1
DS3 DS2 DS1
J73
ACC
L1
TB2
ACC N
120VAC?
CHECK VOLTAGE ON TB2 FROM ACC TO N ON TERMINAL
BLOCK INSIDE CONTROL BOX−SHOULD READ "120" VOLTS AC

V" BLOWER AND VSP1 BLOWER CONTROL BOARD

HEATING MODE CHECKOUT

START HERE
DOES UNIT OPERATE?
CHECK OUT ELECTRONICALLY CONTROLLED BLOWER MOTOR AND
SEE SECTION VIII NEW UNIT START UP
IS 24VAC ACROSS
PIN 8 AND 1
OF VSP1?
12 9 6
IS 24VAC ACROSS J73
PIN 7 AND 1
3
OF VSP1?
1
IS 24VAC ACROSS J73
J73
PIN 3 AND 1
OF VSP1?
IS 24VAC ACROSS R AND C ?
PLACE JUMPER ACROSS R AND W1.
WAIT 75 SECONDS FOR PREPURGE AND FAN ON DELAY.
IS BLOWER ON LOW SPEED
AND IS DS1 LIT?
NO
YES
IS THE ACCESSORY
RELAY PULLED IN?
CONTINUED ON FOLLOWING PAGE
Page 63
NO
VSP1
NO
YES
PRIMARY LIMIT S10 IS NC
ALLOW UNIT TO COOL
NO
IF LIMIT REMAINS OPEN
REPLACE LIMIT
YES
NO
YES
NO
YES
DS3 DS2 DS1
BREAK AND RE
MAKE
JUMPER (R TO W1).
IS 24VAC ACROSS J73
IF UNIT DOES NOT OPERATE
YES
THE GAS VALVE OR IGNI
NO
TION CONTROL ARE NOT
OPERATING PROPERLY
CHECK UNIT WIRING FROM
VSP1 TO TB2 AND IF CORRECT,
YES
CHECK:
1−UNIT POWER
2−INTERLOCK SWITCH
3−TRANSFORMER
4−TRANSFORMER FUSE
5−UNIT WIRING
REPLACE VSP1
CHECK WIRING BETWEEN TB1 AND VSP1
REPAIR IF NECESSARY
S78 IS A NC LIMIT
IS 24VAC ACROSS
ALLOW UNIT TO COOL
J73
IF LIMIT REMAINS
PIN 11 AND 1
OPEN REPLACE
NO
OF VSP1?
YES
PIN 10 AND 1
REPLACE VSP1
NO
OF VSP1?
YES
REPLACE VSP1.
LIMIT