S89E,F DIRECT SPARK IGNITION CONTROL MODULE
68-0066—4
8
IMPORTANT
1. The following service procedures are provided as a
general guide. Follow appliance manufacturer ser-
vice instructions, if available.
2. All meter readings must be taken within the trial for
ignition period. Once the ignition period ends, the
system must be reset by setting the thermostat down
for at least 45 seconds before continuing.
3. If any component does not function properly, make
sure it is correctly installed and wired before
replacing it.
4. The ignition module cannot be repaired. If it
malfunctions, it must be replaced.
5. Only trained, experienced service technicians should
service direct spark ignition systems.
Before beginning troubleshooting, review the normal
operating sequence of the S89. See the Operation section.
Then follow the steps in Fig. 5 to identify the source of the
problem. Some steps are explained in greater detail below.
Besides standard hand tools, you will need the following to
complete the troubleshooting:
1.
Honeywell W136 Test Meter or equivalent.
2.
Test lead: a length of ignition cable or other heavily
insulated wire with both ends stripped 1/2 in. (13 mm).
Check Ignition System Grounding
Nuisance shutdowns are often caused by a poor or erratic
ground.
A common ground is required for the module, igniter, flame
sensor and main burner.
1.
Check for good metal-to-metal contact between the
igniter bracket and the main burner.
2.
Check the ground lead from the GND (Burner) terminal
on the module to the igniter bracket. Make sure
connections are clean and tight. If the wire is damaged
or deteriorated, replace it with no. 14 to 18 gauge,
moisture-resistant, thermoplastic insulated wire with a
221°F (105°C) minimum rating. Use a shield if
necessary to protect the ground wire from radiant heat.
Check Spark Ignition Circuit
The S89 spark generator relay switches 120 Vac to the
remote-mounted spark generator, which, in turn, powers the
spark igniter at the burner. Check as follows:
1.
Shut off gas supply to the gas control.
2.
Disconnect the ignition cable at the spark generator
stud terminal.
3.
Set the thermostat to call for heat.
4.
Reset the S89 by removing power to the module for 45
seconds.
WARNING
Electrical Shock Hazard.
Can cause severe injury, death, or property
damage.
In the next step,
do not touch
either the stripped end of
the test lead or the stud terminal.
5.
Restore power. Before the S89 locks out, touch one end
of the test lead firmly to the S89 GND terminal. Do not
remove the existing ground lead.
6.
Slowly move the other end of the test lead toward the
stud terminal on the spark generator until sparking
stops.
7.
Slowly pull the wire away from the stud terminal and
note the size of the gap when sparking stops.
8.
Follow instructions in Table 3.
Table 3. Spark Ignition Troubleshooting.
Check Flame Sensor and Igniter
1.
Make sure burner flame is capable of providing a good
rectification signal. See Fig. 7.
2.
Make sure about 3/4 to 1 in. (19 to 25 mm) of the flame
sensor is continuously immersed in the flame for best
flame signal. See Fig. 7. Bend the bracket or flame
sensor, or relocate the sensor as necessary. Do
not
relocate the igniter.
3.
Make sure flame does not touch sensor or ignitor
ceramic insulator and that insulators are below he
flame. Excessive heat (over 1000°F [538°C]) will cause
short to ground. Move sensor to cooler location or shield
insulators if excessive heat is suspected. Do
not
relocate the igniter.
4.
Check for cracked igniter or sensor ceramic insulator,
which can cause short to ground, and replace unit if
necessary.
5.
Make sure electrical connections are clean and tight.
6.
Replace damaged wire with moisture-resistant no. 18
wire rated for continuous duty up to 221°F (105°C).
If the Gap Was:
Then:
1/8 in. (3 mm) or more
Generator output voltage is okay.
Less than 1/8 in. (3 mm)
or no spark
Check for 120 Vac at the spark
generator terminals. If okay,
replace the spark generator.