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IS 24VAC ACROSS
J73
PIN 11 AND 1
OF VSP1?
V" BLOWER AND VSP1 BLOWER CONTROL BOARD
HEATING MODE CHECKOUT
NO
DOES UNIT OPERATE?
YES
NO
YES
YES
CHECK VOLTAGE ON TB2 FROM ACC TO N ON TERMINAL
BLOCK INSIDE CONTROL BOX−SHOULD READ "120" VOLTS AC
CHECK UNIT WIRING FROM
VSP1 TO TB2 AND IF CORRECT,
REPLACE VSP1.
DS3 DS2 DS1
PLACE JUMPER ACROSS R AND W1.
WAIT 75 SECONDS FOR PREPURGE AND FANON DELAY.
CHECK OUT ELECTRONICALLY CONTROLLED BLOWER MOTOR AND
VSP1
SEE SECTION VIIINEW UNIT STARTUP
IS 24VAC ACROSS R AND C ?
YES
IS 24VAC ACROSS
PIN 8 AND 1
OF VSP1?
NO
CHECK:
1−UNIT POWER
2−INTERLOCK SWITCH
3−TRANSFORMER
4−TRANSFORMER FUSE
5−UNIT WIRING
IS 24VAC ACROSS J73
PIN 7 AND 1
OF VSP1?
NO
PRIMARY LIMIT S10 IS NC
ALLOW UNIT TO COOL
IF LIMIT REMAINS OPEN
REPLACE LIMIT
YES
IS 24VAC ACROSS J73
PIN 3 AND 1
OF VSP1?
NO REPLACE VSP1
YES
NO
CHECK WIRING BETWEEN TB1 AND VSP1
REPAIR IF NECESSARY
YES
IS 24VAC ACROSS J73
PIN 10 AND 1
OF VSP1?
NO
REPLACE VSP1
YES
IS BLOWER ON LOW SPEED
AND IS DS1 LIT?
BREAK AND RE
MAKE
JUMPER (R TO W1).
YES
NO
S78 IS A NC LIMIT
ALLOW UNIT TO COOL
IF LIMIT REMAINS
OPEN REPLACE
LIMIT
YES
IF UNIT DOES NOT OPERATE
THE GAS VALVE OR IGNI
TION CONTROL ARE NOT
OPERATING PROPERLY
IS THE ACCESSORY
RELAY PULLED IN?
CONTINUED ON FOLLOWING PAGE
TB2
ACC N
120VAC?
DS3 DS2 DS1
L1
ACC
NO
1
3
6912
J73
J73
1
START HERE
1
VSP1
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