Midco J121-DS - Manual (Page 11)

If the Electronic control is changed, the replacement must be identical as to the
make and model number, or must be an authorized substitute.
WARNING: Explosion hazard. Do not use this device if it gets wet. It can
malfunction and cause serious injury or death. Replace any device that has
been wet.
11
Consumer Instructions
FIGURE 5 Ignitor and Flame Sensor Assembly
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.
I. MOTOR WILL NOT RUN
A. Confirm 120V between strip terminals:
1. L2 & L1 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.
II. MOTOR RUNS CONTINUOUSLY, BUT NO FLAME- HOUSING COOL
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.
Part 2
Service
Continued
Trouble Shooting