Reznor SCE Unit Installation Manual - Manual (Page 35)

Form RZ-NA I-SCE, Mfg #207697 Rev 7, Page 35
If the main gas valve fails to open with a normal full size pilot flame established, check for the
following:
a) If voltage between black and brown leads on the main gas valve is 20 to 32 VAC and there is
no main gas flow with the built-in manual valve in FULL OPEN position, the main valve is
defective.
b) If there is no voltage between black and brown leads on the main gas valve, check for
disconnected or shorted flame sensor lead or flame sensor probe.
When the above conditions are normal and the main gas flow is still off, the ignition controller is
probably defective. Do not attempt to service the ignition controller; it does not contain any
replaceable components.
37. Troubleshooting
Reference: If the furnace is equipped with electronic modulation Option AG39 or AG40,
consult the troubleshooting chart, FIGURE 28, page 28.
(continued on page 36)
T op
V iew
Side
V iew
FIGURE 35 - Pilot
Assembly Spark Gap
33. Cleaning
the Heat
Exchanger
To clean the inner surfaces of the heat exchanger, remove the burner rack assembly (See Para-
graph 29.) permitting access to the inside of the heat exchanger tubes.
Clean the tubes using a 1/2" diameter furnace brush. A mirror and flashlight are helpful in examin-
ing the narrow section of each tube. Remove any accumulated dust and soot.
34. Venter Motor Power venter motors are permanently lubricated. No oiling is required.
35. Air Circulation
System
Check blower pulley and motor pulley to be sure they are secured to the shaft. Check belt
condition and belt tension (See Paragraph 17).
36. Limit Control
Check
With the heater on, completely block off the distribution air. The limit control should open within
a few minutes, shutting off gas supply to the main burners.
TROUBLE PROBABLE CAUSE REMEDY
1. No power to the furnace. 1. Turn on power, check supply fuses or circuit breaker.
2. No 24-volt power to venter relay. 2. Turn up thermostat, check control transformer output. Check for loose or
improper wire connections.
3. Venter relay defective. 3. Replace.
4. Defective motor or capacitor. 4. Replace defective part.
1. Manual valve not open. 1. Open manual valve.
2. Air in gas line. 2. Bleed gas line.
3. Dirt in pilot orifice. 3. Remove and clean with compressed air or solvent.
4. Gas pressure too high or too low. 4. Adjust supply pressure. (See Paragraph 10).
5. Kinked pilot tubing. 5. Replace tubing.
6. Pilot valve does not open. 6. If 24 volt is available at the valve, replace valve.
7. No spark: 7.
a) Loose wire connections a) Be certain all wires connections are solid.
b) Transformer failure. b) Be certain 24 volts is available.
c) Incorrect spark gap. c) Maintain spark gap at .100".
d) Spark cable shorted to ground. d) Replace worn or grounded spark cable.
e) Spark electrode shorted to ground. e) Replace pilot if ceramic spark electrode is cracked or grounded.
f) Drafts affecting pilot. f) Make sure all panels are in place and tightly secured to prevent drafts at pilot.
g) Ignition control not grounded. g) Make certain ignition control is grounded to furnace chassis.
h) Faulty ignition controller. h) If 24 volt is available to the ignition controller and all other causes have been
eliminated, replace ignition control.
8. Optional lockout device interrupting control circuit
by above causes. 8. Reset lockout by interrupting control at thermostat.
9. Faulty combustion air proving switch. 9. Replace combustion air proving switch.
Venter motor will not
start
Pilot will not light --
Venter operating