Finish Thompson BE-55C - Manual (Page 26)

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Possible Cause 3: Clogged Drain Valve
Check for residues or debris blocking the drain valve. This can occur if there were solids or sediment
sucked into the unit with the waste coolant. This can also occur if residue is processed more than once
(which is not recommended) or if residues are continuously remixed into the waste coolant.
1. Place a drain pan (capable of handling hot liquids) under the drain valve and open the valve.
 Insert and rotate a stiff wire (like a coat hanger) into the drain valve to attempt to break the clog
free. Use extreme caution, the residues may break loose and rush out. It may be necessary to
remove the drain valve and insert the wire directly into the process tank.
2. Another way that has been proven to be successful is to close all valves and depress the Fill Switch
until a vacuum level of -10” Hg. is reached. Open and close the drain valve rapidly to allow
incoming air to pass through blockage. Fill process tank with 5 gallons of water to dilute residue to
drain.
 If blockage does not relieve, remove heater tube assembly and clean out the tank and piping
manually (call factory for further instructions).
 After the clog has been cleared, perform a “detergent flush” as outlined in the “Maintenance: Semi-
annually” section of this manual.
Possible Cause 4: Low Level Control Probe is shorted to ground
If the Low Level Control Probe has shorted to ground, the unit will continue running after the residues of
the waste coolant have dropped below the recommended low level. This will allow the unit to continue
heating until all or most of the liquid has evaporated. Check the Low Level Control Probe and it’s wiring
for shorts to ground.
 If the Low Level Control Boards LED is not lit, proceed to Possible Cause 5.
 If the Process Tank is empty, and the LED is lit, there is a short to ground with the Low Level Probe
or its wiring.
1. 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).
2. Remove wire #23 from the probe and check the LED on the Low Level Control Board. If the LED
goes out, then the probe itself is making contact to ground. This can be confirmed by checking
continuity between the terminal on the top of the probe and the pipe.
3. 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.