Table 30 continued: Lockout Errors
Display Information
Alert
Description
Possible Cause
Solution
EO2
Primary Limit / Fuse
Failure
The control board safety
fuse has blown or the
primary temperature limit
has opened indicating safe
operating temperatures
for this furnace have been
exceeded.
A. Improper circulating
airflow
1. Check filter / replace if
dirty .
2. Check for improperly
sized duct system.
3. Check for faulty blower
motor .
4. Check for faulty blower
motor wiring.
B. Primary limit switch
failure
1. Check for an open
primary limit switch at
ambient temperature .
C. Fuse is blown
1. Check and replace fuse
on the board.
2. Make sure fuse socket
is tight, crimp fuse
terminals if necessary.
D. Faulty primary limit
switch wiring
1. Check primary limit
wiring continuity from
the switch to the control
board .
EO3
Modulation Valve Failure
The control lost the
position feedback from
the modulating gas valve
actuator.
A. Faulty modulation valve
actuator wiring
1. Insure wiring is
connected per unit
wiring diagram.
2. Check for loose pins or
bad connections.
3. Check for frayed wiring
or shorts to ground.
B. Modulation valve
actuator failure
1. Insure actuator has 24
V power.
2. Insure actuator is
receiving valid drive
signal from the control
board (2 – 10 VDC).
3. Check for actuator
feedback to the control
board (2 – 10 VDC).
EO4
Air Sensor Failure
Pressure Sensor Reading
Low
The air sensor reading
is too low for operating
conditions or the air
pressure switch closed
when the sensor indicates
low flow.
The pressure switch MUST
be open prior to inducer
activation.
A. Faulty wiring or
connections
1. Check pressure switch
wiring.
2. Check inducer wiring.
3. Check for plugged or
disconnected vacuum
hoses.
B. Faulty pressure switch
1. Replace pressure
switch.
C. Faulty pressure sensor,
located on the board
1. Replace board.
EO5
Air Sensor Failure
Pressure Sensor Reading
High
The air sensor reading is
too high when the inducer
is off or the air pressure
switch open when the
sensor indicates high flow.
The pressure switch MUST
close to initiate an ignition
sequence.
A. Faulty wiring or hose
connections
1. Check pressure switch
wiring.
2. Check inducer wiring.
3. Check for broken or
disconnected vacuum
hoses.
B. Blocked or improper
venting
1. Check air inlet and
outlet for blockage.
2. Check venting
configuration for
excessive venting
length, improper sizing,
etc.
C. Faulty pressure switch
1. Replace pressure
switch.
Optional Gas Heat
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73
IM 1125-13 • REBEL ROOFTOPS
