Status Code 11
NO PREVIOUS CODE—STORED STATUS CODES ARE ERASED AFTER 48 HR OR WHENEVER POWER SOURCE (115-VAC
OR 24-VAC) IS INTERRUPTED. RUN SYSTEM THROUGH A HEATING OR COOLING CYCLE TO CHECK SYSTEM.
Status Code 12
BLOWER ON AFTER POWER UP—BLOWER WILL RUN FOR 90 SEC WHEN FURNACE POWER IS INTERRUPTED AND LATER
RESTORED DURING A CALL FOR HEAT (R-W/W1 CLOSED). IF THIS STATUS CODE REPEATS EVERY COUPLE OF MINUTES,
IT IS PROBABLY CAUSED BY A DIRECT SHORT IN PRESSURE SWITCH CIRCUITS, GAS VALVE GV, WIRING TO GAS VALVE
GV, OR HUMIDIFIER COIL.
STEP
ACTION
YES
NO
GO TO
1.
Remove blower door and disconnect W/W1 thermostat lead from 2-stage fur-
nace control.
—
—
2
2.
Depress door switch. Use piece of tape to hold switch closed.
—
—
3
3.
Set thermostat to call for heat and set thermostat fan control to AUTO position if
equipped. Reconnect W/W1 thermostat lead to 2-stage furnace control.
—
—
4
4.
Does furnace keep repeating the following cycle?
Induced draft motor IDM runs, induced draft motor IDM stops, blower motor
BLWM runs for 90 sec while RED LED status light flashes status code 12.
5
20
—
5.
Do you have less than 17 vac across R and C
OM
-24V on 2-stage furnace con-
trol?
6
14
—
6.
Do you have less than 90 vac across PR1 and PR2 on 2-stage furnace control?
7
10
—
7.
Make sure wire gage between main fuse box and furnace complies with wire
size specification in Installation, Start-Up, and Operating Instructions.
—
—
8
8.
Fix problem.
—
—
9
9.
Go to page number indicated in Index for CLEANUP AND START-UP IN-
STRUCTIONS.
—
—
INDEX
10.
Disconnect R thermostat lead.
—
—
11
11.
Do you have less than 19 vac across R and C
OM
-24V on 2-stage furnace con-
trol?
12
13
—
12.
Replace transformer.
—
—
9
13.
The thermostat and/or thermostat wires are loading down transformer. Replace
thermostat or repair thermostat wires.
—
—
9
14.
Does hot surface ignitor HSI come on during cycle?
15
19
—
15.
Disconnect humidifier lead from HUM terminal on 2-stage furnace control.
—
—
16
16.
Does furnace still alternately cycle induced draft motor IDM and blower motor
BLWM as described in Step 4.
18
17
—
17.
There is a direct short in wiring to humidifier solenoid coil, diode bridge (if
used), or humidifier solenoid coil.
—
—
8
18.
There is a short in gas valve GV or wiring to gas valve GV. Refer to Appendix
G to check gas valve GV.
—
—
8
19.
There is a direct short in YELLOW wire from low-heat pressure switch LPS.
—
—
8
20.
While unit is operating in low heat, jumper R and W2 thermostat terminals.
—
—
21
21.
Does furnace abruptly shut down with no inducer post-purge and then run
blower motor BLWM for 90 sec while RED LED status light flashes status code
12.
22
26
—
22.
Disconnect BROWN wire to gas valve GV.
—
—
23
23.
Does furnace still abruptly shut down as described in Step 21?
25
24
—
24.
Replace gas valve.
—
—
9
25.
There is a direct short to ground in GRAY or BROWN wires connected to high-
heat pressure switch HPS.
—
—
8
26.
Power to furnace was probably interrupted, or line voltage was too low during a
call for heat. This is normal operation. Go to page number indicated in Index for
CLEANUP AND START-UP INSTRUCTIONS.
—
—
INDEX
—12—
