Finish Thompson BE-15/15C - Manual (Page 24)

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PROBLEM: UNIT KEEPS RUNNING AFTER THE ON/OFF SWITCH IS OFF.
Electrical shock hazard present.
Electrical servicing should be performed by a qualified electrician.
Possible Cause 1: Improper electrical hook-up.
Verify that the power supply leads are correct from the main circuit. If the colors of the wire leads are
misinterpreted, “hot” leads or “neutral” leads can be connected incorrectly causing power to be fed back
through the electrical system of the unit.
 For a three-wire 208-240 VAC system, the black and white wires should be “hot” (L1 and L2) and
the green should be “ground” (G). No “neutral” should be present.
 For a four-wire 208-240 VAC system, the black or red wires should be “hot” (L1 and L2), the white
wire should be “neutral” (N), and the green should be “ground” (G).
Check main power supply and wiring to the unit.
 E92 or older units require a 4-wire (L1, L2, Neutral, and Ground) 240 VAC, single-phase electrical
supply. If a neutral wire is not available, connect the Ground to the “G” and the “N” position of the
terminal strip in the BE’s circuit box.
 F92 and newer units require a 3-wire (L1, L2, and Ground) 240 VAC, single-phase electrical supply.
No neutral wire should be used or connected to the terminal strip in the BE’s circuit box.
If the power supply and wiring to the unit is as above and correct, proceed to Possible Cause 2.
Possible Cause 2 & 3: Contactor stuck in engaged position or On/off Switch is faulty.
Determine whether a Contactor is mechanically stuck or fused into the engaged position. Contactors are
located in the Circuit Box inside the BE unit. This can occur if the unit is subject to over-voltage or a surge.
Even if there is only 240 volts between the “hot” leads to the Contactor, uneven loads or miswiring in the
main electrical system can cause an imbalance of potential from “hot” to “neutral” or “ground”. One of the
“hot” leads may have a much higher voltage than the other and can exceed the rating of the Contactor.
 E92 or older units use two Contactors—one controls the fan and pump motors, and the other controls the
Heater Band. Determine whether there is 120 volts to the coil of each Contactor (between wires #13 and
#18). If there is no voltage and the Contactor is engaged, replace the Contactor. This can be verified by
disconnecting power to the BE unit and checking whether the contacts are still physically engaged. If
there is voltage, the problem lies elsewhere such as a faulty On/off Switch.
 F92 and newer units use one Contactor to control the fan motor, pump motor, and Heater Band.
Determine whether there is 240 volts to the coil of the Contactor (between wires #13 and #18). If there is
no voltage and the Contactor is engaged, replace the Contactor. This can be verified by disconnecting
power to the BE unit and checking whether the contacts are still physically engaged (the gray button
should spring left then return when pushed). If there is voltage, the problem lies elsewhere such as a
faulty On/off Switch.
WARNING: