Honeywell F90A1050 - Page 18

F90A,B SELF-CONTAINED COMMERCIAL ELECTRONIC AIR CLEANER
68-0103-6 Revised 11-07
17
Fig. 20. F90 electrical troubleshooting procedure.
START
LED ON/FAN ON
NO
YES
YES
YES
NO
DAMAGED
"ON" LED OFF/FAN OFF
"ON" LED ON/FAN OFF
"ON" LED OFF/FAN ON
NO
NO
NO
YES
NO
YES
NO
YES
NO
YES
YES
NO
NO
YES
YES
YES
FAN 
OFF
FAN 
ON
YES
YES
CELL 
SHORTED
INFINITE RESISTANCE
NO
YES
YES
ELECTRONIC COMPONENTS ON POWER SUPPLY BOARDS ARE NOT FIELD REPLACEABLE. ATTEMPTED SERVICE WILL DAMAGE 
BOARDS . IF TROUBLESHOOTING INDICATES A POWER SUPPLY PROBLEM, REPLACE THE ENTIRE POWER SUPPLY ASSEMBLY.
TO USE THIS CHART:

1. FOLLOW THE STEPS IN EXACT SEQUENTIAL ORDER. 
2. EACH TIME YOU ISOLATE AND FIX A PROBLEM, GO BACK TO START.
3. REPEAT ALL THE STEPS UNTIL THE AIR CLEANER CHECKS OUT OK.
NO
NO
MAKE SURE CELLS 
ARE CLEAN, DRY, 
PROPERLY INSTALLED.
CLOSE COVER OR
DEFEAT INTERLOCK.
TURN AIR CLEANER 
ON. CHECK FAN 
OPERATION AT LO, 
MED, HI SPEEDS.
OBSERVR "ON'' LED.
PUSH TEST BUTTON. 
LISTEN FOR 
SNAPPING SOUND.
HOLD DOWN TEST 
BUTTON. IS 
"CHECK" LED LIT?
RELEASE TEST 
BUTTON. IS 
"CHECK" LED LIT?
IS "WASH" LED LIT?
TURN OFF AIR 
CLEANER. SHORT 
IONIZER TO FRAME 
WITH TEST LEAD. 
TURN ON AIR 
CLEANER. IS 
"WASH" LED LIT?
CLEAN CELLS, 
WIPING IONIZER 
WIRES. INSPECT 
CELLS FOR 
DAMAGED IONIZER 
CONTACTS.
REPLACE OR 
REPAIR CELLS.
REMOVE CELLS. IS 
"WASH" LED LIT?
AIR CLEANER OK.
REPAIR OR REPLACE 
CELL(S)
WITH OHMMETER, 
CHECK FOR SHORT 
BETWEEN:
- CELL FRAME AND
COLLECTOR 
TERMINAL.
- CELL FRAME AND
IONIZER TERMINAL.
IS "CHECK" LED LIT?
CHECK INPUT 
VOLTAGE TO LED.
REPLACE LED.
REPLACE POWER 
SUPPLY AND LED 
DRIVER BOARD.
INSPECT CELLS FOR:
- BENT COLLECTOR 
PLATES
- BROKEN IONIZER 
WIRES
- DIRT ON 
INSULATORS
- DAMAGED IONIZER
OR COLLECTOR 
CONTACT TABS
REPLACE CELLS
NO
CELLS OK.
REPLACE SWITCH.
CHECK INPUT VOLTAGE 
TO INTERLOCK SWITCH.
TURN AIR CLEANER OFF. OPEN COVER. 
DEFEAT INTERLOCK. CHECK FOR INPUT 
VOLTAGE TO SWITCH.
CHECK WIRING BACK 
THROUGH POWER CORD 
AND OUTLET TO CIRCUIT 
BREAKER OR FUSE.
CORRECT WIRING 
OR FUSING.
ADJUST/REPAIR/
REPLACE 
INTERLOCK 
SWITCH.
TURN AIR CLEANER OFF. OPEN COVER. 
REMOVE ACCESS PANEL. DEFEAT INTERLOCK. 
TURN AIR CLEANER ON. JUMPER SWITCH 
CONTACTS FOR EACH SPEED IN TURN.
REPLACE 
SWITCH.
JUMPER ORANGE 
WIRE TO WIRE FROM 
SPEED CONTROL 
MODULE TO 
FAN MOTOR
HOLD TEST BUTTON 
DOWN; DOES "CHECK" 
LED LIGHT?
CHECK FOR 
VOLTAGE 
TO "ON" LED.
REPLACE POWER 
SUPPLY AND LED 
DRIVER BOARD.
REPLACE LED.
REPLACE 
POWER 
SUPPLY.
TURN UNIT OFF. OPEN COVER. REMOVE 
ACCESS PANEL. DEFEAT INTERLOCK. TURN 
AIR CLEANER ON. CHECK FOR CORRECT 
INPUT VOLTAGE TO POWER SUPPLY: CHECK 
BOARD TERMINALS P1 AND P2.
PUSH TEST BUTTON. LISTEN FOR SNAPPING 
SOUND.
CHECK WIRING BACK THROUGH SWITCH, 
INTERLOCK, POWER CORD, 
OUTLET, AND CIRCUIT BREAKER.
CORRECT WIRING.
M1525B
TURN OFF POWER. MAKE SURE FAN 
MOTOR ROTATES FREELY. REPLACE 
FAN MOTOR IF NECESSARY.
REPLACE SPEED 
CONTROL MODULE
FAN 
ON
FAN 
OFF
TURN OFF POWER. 
MAKE SURE FAN 
MOTOR ROTATES 
FREELY. REPLACE 
FAN MOTOR IF 
NECESSARY.
F90A
F90B
1
1
1
RISK OF ELECTRIC SHOCK
THESE SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL ONLY. TO REDUCE RISK 
OF ELECTRIC SHOCK, DO NOT PERFORM ANY SERVICING OTHER THAN CONTAINED IN THE OPERATING 
INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO SO.
WARNING