Instruction manual

82
21 GAS HEATING LOCKOUT – Turn off
power and wait 5 minutes to retry. Check for: - Stuck closed gas valve relay on control. - Miswire or short to gas valve wire.
22 ABNORMAL FLAME-PROVING SIGNAL
Flame is proved while gas valve is de- energized. Inducer will run until fault is cleared. Check for: - Stuck o
p
en or leak
yg
as valve.
23 PRESSURE SWITCH DID NOT OPEN –
Check for:
- Obstructed pressure tube. - Pressure switch stuck closed.
24 SECONDARY VOLTAGE FUSE IS OPEN
Check for: - Short circuit in secondary voltage (24V)
wiring including thermostat leads. Disconnect thermostat leads to isolate short circuit.
32 LOW-HEAT PRESSURE SWITCH DID
NOT CLOSE OR REOPENED – If open longer than 5 minutes, inducer shuts off for 15 minutes before retry. If opens during blower on-delay period, blower will come on for the selected blower off-delay. Check for: -Properventsizing. - Air leak between vestibule and blower
compartment.
- Low inlet gas pressure (if LGPS used). -Restrictedvent. - Disconnected or obstructed pressure
tubing.
- Defective or miswired pressure switches
-Excessivewind. - Plugged condensate drain. - Water in vent piping, possible sagging
pipe.
- Defective inducer motor. - Low inducer voltage (115V)
33 LIMIT CIRCUIT FAULT – Indicates the
limit or a flame rollout switch is open or the furnace is operating in high-heat only mode due to 2 successive low-heat limit trips. Blower will run for 4 min. or until open switch remakes whichever is longer. If open longer than 3 min., code changes to lockout #13. If open less than 3 min. status code #33 continues to flash until blower shuts off. Flame rollout switch requires manual reset. Check for: - Loose blower wheel.
- Defective switch or connections.
- Improper low- or high-heat gas input
adjustment.
- Improper limit switch or no limit gasket. - Dirty filter or restricted duct system.
34 IGNITION PROVING FAILURE – If flame is
not sensed during the trial for ignition period, the control will repeat the ignition sequence 3 more times before lockout #14 occurs. If flame signal is lost during the blower on-delay period, blower will come on for the selected blower off-delay. Check the following items first before proceeding to the next step. - Gas valve turned off.
- Manual shut-off valve.
- GREEN/YELLOW wire MUST be
connected to furnace sheet metal.
- Flame sensor must not be grounded. To determine whether the problem is in the gas valve, igniter, or flame sensor the system can be operated in component test mode. To check the igniter remove the R thermostat connection from the control, reset power, and put setup switch SW1-6 in the ON position to start the component test. Does the igniter glow orange/white by the end of the 15 second warm-up period?
Unplug igniter harness from control and repeat component test by turning setup switch SW1-6 OFF and then back ON. Check for 115V between pin 3 and NEUTRAL-L2 on the control. Was 115V present for the 15 second period?
Check connections and retry. If current is near typical value (4.0-6.0 nominal) and burners will not stay on, repeat check in high-heat. If burners will still not stay on replace control. If burners operate in high-heat then switch to low- heat, check manifold pressure. If OK, check burner carryover and flame sensor location.
Clean flame sensor with fine steel wool and recheck current. Nominal current is 4.0 to 6.0 microamps. Is current near typical value? Replace electrode. Will main burners ignite and stay on? Replace furnace control. Fixed.
NO YES
YES YES
NO NO
15 BLOWER MOTOR LOCKOUT – Indicates
the blower failed to reach 250 RPM or the blower failed to communicate within 30 seconds after being turned ON in two successive heating cycles. Control will auto-reset after 3 hours. See code 41.
45 CONTROL CIRCUITRY
LOCKOUT Auto-reset after 1 hour lockout due to:
- Flame circuit failure.
- Gas valve relay stuck
open.
- Software check error. Reset power to clear lockout. Replace control if code repeats.
Replace furnace control. Check for continuity in the harness and igniter. Replace defective component.
Reconnect the R thermostat lead and set thermostat to call for heat. Connect voltmeter across gas valve connections. Does gas valve receive 24V? Does gas valve open and allow gas to flow? Do the main burners ignite? Do the main burners stay on?
Allowblowertocomeonand repeat test to check for intermittent operation. Check that all gas valves are turned on. Replace valve. Check connections. If OK, replace control. Check for: - Inadequate flame carryover
or rough ignition.
- Low inlet gas pressure. - Proper firing rate.
Repeat call for heat and check flame sensor current during trial for ignition period. Is the DC microamps below 0.5?
YES
YES
YES YES
YES NO NO
NO
NO NO NO
43 LOW-HEAT PRESSURE SWITCH OPEN
WHILE HIGH-HEAT PRESSURE SWITCH IS CLOSED - Check for: - Low-heat pressure switch stuck open. - Disconnected or obstructed pressure
tube.
- Miswiredpressureswitches.
- Low inlet gas pressure (if LGPS used). - Plugged condensate drain. - Water in vent piping, possible sagging
pipe.
25 INVALID MODEL SELECTION OR
SETUP ERROR – If status code 25 only flashes 4 times on power-up the control is missing its model plug PL4 and is defaulting to the model selection stored in memory. If status code 25 flashes continuously it could indicate any of the following: - Model plug PL4 is missing and there is
no valid model stored in permanent memory. This will happen if you forget to install the model plug PL4 on a service replacement control.
- Thermostat call with SW1-1 ON. - Thermostat call with SW1-6 ON. -SW1-1andSW1-6bothON. - Two different furnace models twinned. - Service replacement control is incorrect.
Need non-modulating board with software version V17 or later.
31 HIGH-HEAT PRESSURE SWITCH OR
RELAY DID NOT CLOSE OR REOPENED - Check for: - Control relay may be defective. - Gas valve is miswired. - See status code 32.
A113325B
Troubleshooting Guide (Continued)
986TA