Bryant 333B-AV-036060-AA-JA Troubleshooting Manual page 8

START HERE—IF A PROBLEM EXISTS, THE SERVICE TECHNICIAN SHOULD ALWAYS BEGIN TROUBLESHOOTING HERE.
SPECIAL NOTE: ALL VOLTMETERS ARE NOT THE SAME; YOUR VOLTAGE READINGS WILL VARY. THIS APPLIES TO THE
ENTIRE CONTENT OF THIS TROUBLESHOOTING MANUAL. THEY ARE NOT ABSOLUTE VALUES. CORRECT 115-VAC
VOLTAGE, CURRENT, AND POWER MEASUREMENTS CANNOT BE MADE ON ICM FURNACES UNLESS USING A TRUE RMS
METER.
STEP
Remove control door first. DO NOT REMOVE BLOWER DOOR! Removing
blower door interrupts power (115-vac or 24-vac) and erases previous status
1.
codes stored in memory.
Is RED LED status light on?
2. Is RED LED status light blinking rapidly without a pause?
3. Go to page number indicated in Index for RAPID FLASHING LED.
Is RED LED status light blinking ON/OFF slowly with a combination of short and
4.
long flashes?
Determine status code. The status code is a 2 digit number with the first digit
5. determined by the number of short flashes and the second digit by the number
of long flashes.
6. Go to page number indicated in Index for section covering the status code.
To retrieve previous codes, no thermostat inputs to control must be present and
all time delays must have expired. Disconnect 1 of the RED main limit wires 1
to 4 sec until RED LED status light goes out, then reconnect it and read status
code. To recover additional codes repeat this procedure. The 2-stage furnace
7.
control is capable of retaining 5 previous status codes.
NOTE: DO NOT leave RED wire disconnected for longer than 4 sec as control
will assume an over-temperature condition exists and will respond with indoor
blower operation.
Was there a previous status code other than code 11?
8. NOTE: Status codes are erased after 48 hr or whenever power (115-vac or 24-
vac) is interrupted.
Go to page number indicated in Index for section covering the first previous sta-
9.
tus code.
10. Does problem appear to be low cooling airflow?
Go to page number indicated in Index for section covering IMPROPER COOL-
11.
ING AIRFLOW.
Set thermostat to call for heat and set thermostat fan control to AUTO position if
12.
equipped.
13. Does furnace respond to the call for heat?
Observe operation of furnace for 20 minutes or until RED LED status light starts
14.
blinking.
Does RED LED status light blink ON/OFF slowly with a combination of short
15.
and long flashes?
Is temperature rise below range specified on rating plate when unit is operating
in high heat?
16. NOTE: If temperature rise is above range specified on rating plate, refer to
Start-Up and Adjustment section in Installation, Start-Up, and Operating Instruc-
tions.
Go to page number indicated in Index for section covering HIGH HEAT TEM-
17.
PERATURE RISE TOO LOW (COLD BLOW).
Go to page number indicated in Index for CLEANUP AND START-UP IN-
18.
STRUCTIONS.
19. Make sure power is being supplied to furnace.
Check fuses, breakers, or manual disconnects to be sure they are correctly set.
20.
If not, reset them and go back to Step 1.
Remove blower door and depress door switch. Use a piece of tape to hold
21.
switch closed.
22. Do you have 115 vac across L1 and L2?
Turn power off. Check continuity of power leads and door switch. If necessary
23.
repair power leads and/or replace door switch.
24. Do you have 24 vac across SEC-1 and SEC-2?
25. Replace 2-stage furnace control.
26. Do you have 115 vac across PR1 and PR2?
Replace transformer. If transformer fails again, replace transformer and 2-stage
27.
furnace control.
28. Do you have 24 vac across W/W1 and C
You have a defective thermostat or a break in wiring between thermostat and
29.
furnace. Fix problem.
ACTION
-24V on 2-stage furnace control?
OM
—8—
YES NO GO TO
2 19 —
3 4 —
— — INDEX
5 7 —
— — 6
— — INDEX
— — 8
9 10 —
— — INDEX
11 12 —
— — INDEX
— — 13
14 28 —
— — 15
5 16 —
17 18 —
— — INDEX
— — INDEX
— — 20
— — 21
— — 22
24 23 —
— — 18
25 26 —
— — 18
27 25 —
— — 18
25 29 —
— — 18