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Upright Portable Hot Oil TCUs Chapter 6: Troubleshooting 37
Problem Possible cause Corrective action
Loss of fluid in process.
Check all lines/connections/
fittings.
Vent valve open.
Allow vent timer to run out; or,
check valve operation when unit
is cold by opening the fill port.
Faulty/dirty solenoid valve;
usually detected when there is a
steady stream or trickle of water
out of the drain line.
Switch to Manual Cool mode
several times to flush valve. If
the leak continues, disconnect
the power to the unit, turn off
the water supply, and clean or
replace the solenoid.
Unit does not heat properly/can
not achieve set point.
Degraded fluid. Drain and replace fluid.
Defective heater contactor.
Visual inspection of coil and
contacts. Repair/replace
defective contactors.
Defective immersion heater.
Check resistance on all three (3)
legs of heater with an ohmmeter.
If not all equal, contact factory
for replacement heater.
Heater burnout.
Check heater tank for scorched/
discolored paint. Check
resistance on all three (3) legs of
heater with an ohmmeter.
Replace heater as needed.
Controller heater output open.
Check the heater output with an
ohmmeter to ground. It should
read in the mega-ohm range.
Infinite or zero readings indicate
a defective output.
Unit does not heat.
Clogged Y strainer. Clean Y strainer.
Water supply to unit is turned
OFF.
Open water supply.
Water drain is plugged or
excessive back pressure in drain
line.
Clear drain line or eliminate
back pressure condition.
Heat exchanger tubes plugged
by lime deposits.
Remove tube bundles; clean/
replace as required.
Unit overheats/unable to cool.
Faulty solenoid valve.
Test solenoid valve by switching
to Manual Cool mode and listen
for valve operation. Replace if
faulty.