Finish Thompson BE-55C - Manual (Page 27)

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Possible Cause 5: Low Level Control Board Failure
Caution: Disconnect electrical power to the BE unit before performing tests on the
Low Level Control Board.
If the Low Level Control Board is defective or a false ground has occurred, the unit will continue running
after the waste coolant drops below the recommended low level. This will allow the unit to continue
heating until all or most of the liquid has evaporated. With power to the unit off, check continuity
between wires #18 and 26
 if there is no continuity, this part of the system is O.K.
 if
there is continuity, you will need to check the low level probe. Locate the Low Level Probe. It is
towards the bottom, right side of the process tank, it is inserted into a pipe, connected to the tank
(the top of the probe resembles a spark plug, there will be a white wire (#23) attached to the top of
it).
If there is continuity, remove the probe from the pipe, and thoroughly clean the probe and the inside
of the pipe. Residue build-up can form a “bridge” between the probe and the pipe. Check whether
the probe is straight. If the probe is slightly bent, it may touch the side of the pipe. Straighten if
necessary, reinstall the probe and recheck for continuity.
Possible Cause 6: Air or Water Solenoid is Defective
The air solenoid (SOL3) is “normally closed” and should open when the drain assist switch is
depressed, allowing air pressure to enter the tank (should be regulated at 10psi).
The water solenoid (SOL1) is “normally open” and should close when the drain assist switch is
depressed, preventing the pressurized air from coming out of the processed water hose.
 A simple way to check these solenoids is listen for a clicking noise at the solenoid when the switch
is depressed. Furthermore, to check the water solenoid, check to see if air is coming out of the
discharge hose (you would hear a “whooshing” sound), if you do, the valve is not closing and may
need cleaned or replaced.
PROBLEM: PRESSURE RELIEF VALVE KEEPS DISCHARGING
Possible Cause 1: Stuck/Faulty Divert Solenoid Valve.
Determine whether the Divert Valve is stuck between two positions. During normal operation, the
Distillate Piping is open and at atmospheric pressure during the process. Once the glycol process
begins, the Divert Valve switches positions to allow the Distillate Piping and the Process Tank to be
under up to 28” Hg. of vacuum.
 If the unit “belches” while filling the Process Tank or reads a partial vacuum during the water
process, the Divert Solenoid Valve is stuck between two positions. A stuck Divert Valve can allow
air to enter through the process Water Hose during the vacuum portion of the cycle.
Refer to the “Service Procedures: Divert Valve Repair or Replacement” section of this manual for
further instruction on servicing the Divert Valve.