Midco J83-DS - Manual (Page 10)

TROUBLE CHART
Make sure the thermostat and operating controls are calling for heat. Defective wiring or loose
connections can simulate the component defects outlined below. Check associated wiring
before replacing a component.
ELECTRICAL AND FLAME CHECKS MUST BE MADE IN THE ORDER LISTED.
A. Confirm 120V between strip terminals:
1. L1 & L2 no voltage - Fused disconnect off or Fuse open.
2. L2 & 3 no voltage - Optional on/off and/or safety controls open.
3. L2 & 4 no voltage - Burner Switch or Timer open and/or Remote Switch or Timer
open.
4. L2 & Thermal Switch terminal 1 (black wire).
a. None - Thermal Switch is defective.
b. Yes - Motor is defective.
A. Confirm that Main Manual Shut-Off Valve is open.
B. Check for 120V between strip terminals 4 and L2.
1. Yes - turn Burner Switch or Timer off for a minimum, of 30 seconds to RESET
Electronic Control.
2. No voltage, Thermal Switch is defective.
C. Check for 24V* between strip terminals 6 to 10. No voltage, transformer is defective.
D. Check for 24V* between strip terminals 5 and 10. No voltage, motor interlock switch
is defective.
E. Check for 24V* between Electronic Control 24 (PWR) terminal and strip terminal 10. 24V -
yellow wire from strip terminal 10 is defective.
F. Check for 24V* between Electronic Control 24 (GND) terminal and strip terminal 10. No
voltage, red wire from terminal strip 5 is defective.
G. Turn burner control off for a minimum of 30 seconds to RESET Electronic Control for each
of the following steps.
CAUTION: Tests are valid only during the 6 second trial for ignition.
1. Check for 24V* between Electronic Control Valve terminal and strip terminal 10. No
voltage, Electronic Control or Fuse is defective.
2. Check for 24V* between strip terminals 7 and 10. No voltage, blue wire from strip
terminal 7 is defective.
3. Check for ignition spark (spark length approximately 1/8"):
a. Between Electronic Control HI VOLTAGE terminal and earth ground. No
spark, Electronic Control or Fuse is defective.
b. Between electrode wire and Spark Electrode. No Spark, Electrode wire is
defective.
c. Check for spark between Spark Electrode and ground barrier. See Figure 5.
If ignitor tip is not visible with burner mounted, but spark can be heard, contin-
ue with Step G4. If spark cannot be heard, refer to Section VIII Ignitor and
Regulator Assembly for spark test.
4. Connect manometer to Ignitor Gas Pressures Test Tap and, during 6 second trial for
ignition period, check gas pressure.
a. No pressure, confirm that pressure of at least 4" W.C. is available at inlet of
automatic gas valve (connect manometer to valve upstream tap) and repeat
Step G4. If still no ignitor gas pressure, valve is defective.
b. Ignitor gas pressure 3" to 4" W.C., continue with Step G5.
c.
Adjust the ignitor regulator to 3.5" W.C. while gas is flowing.
5. Open charging door, make sure any Door Open interlock is bypassed, and repeat trial
for ignition.
a. With flame on, close charging door and check combustion chamber pressure,
burner peep hole can be used for access to obtain approximate reading.
Make sure sensing tube extends into the combustion chamber at least 6".
Pressure should be between 0" and minus 0.5" W.C. If pressure is on the
high negative side of the range, increase the ignitor gas pressure to 4" or 5"
W.C.
b. No flame, clean and test ignitor assembly per Section VIII Ignitor and
Regulator Assembly.
10
Trouble Chart
I Motor Will Not Run
II Motor Runs
Continuously, but
No Flame-Housing
Cool