American Dryer Corp. MLG-460 - Manual (Page 69)

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4b) To check “Interlock 2” (Heater Doors), verify that there is a 110 VAC signal on TB-41, on the Main
Electrical Panel, when PLC (Programmable Logic Controller) output #4 is on.
NOTE: The heater door interlock switches are double-pole double-throw (DPDT). These switches
affect different circuits.
• If there is 110 VAC at the panel go to paragraph #5b below.
• If there is not a signal, check circuit back to the burner door switches. Refer to the ML-460
Solenoid Junction Box Wiring Diagram for connection information.
5b) A quick way to check the load and unload door switches is to close the unload door (2-Door models)
and toggle the load door’s “wobble arm,” and monitor INPUT #6 of the PLC (Programmable Logic
Controller). Likewise, for 2-door models, close the load door and toggle the Unload door’s “wobble
arm,” also monitor INPUT #7 of the PLC.
NOTE: The rotary arm switches mentioned are double-pole double-throw (DPDT), where the PLC
(Programmable Logic Controller) signal and “door” switch effect different circuits.
• If input #6 L.E.D. (light emitting diode) of the (Programmable Logic Controller) goes on and off,
the signal is “good.” Go to Section #5 on page 69 and page 70.
• If input #6 L.E.D. of the PLC doesn’t react, then perform the following
• Power down the dryer.
• Close the Load and Unload doors.
• Check for continuity between TB1-70 and TB1-7 on the Main Electrical Panel
Refer to the dryer Main Panel Wiring Diagram.
• If no continuity, refer to the dryer Tumbler Junction Box Wiring diagram for detail information
for door switch wiring.
6b) To check interlock 3 (PRS1 and PRS2), Gas pressure Hi/Lo switch:
• Power down the dryer.
• Check for continuity between TB1-18 and TB1-19.
• If no continuity, refer to the dryer Solenoid Junction Box wiring diagram for detail information
for PRS1 and PRS2 wiring.
4. “HEATER FAULT” Message
PLC (Programmable Logic Controller) MESSAGE - “HEATER FAULT”
a) PROBABLE CAUSES;
1a) Fuse 6.