Technical data

28
PROBLEMS POSSIBLE CAUSES YOU SOULD TRY THIS
8
The 20-minute push-button
or the 20/40/60-minute
push-button timer does
not work OR its indicator
light does not stay on.
• The switch may be defective.
9
The defrost cycle does not
work (the fresh air duct
is frozen OR the fresh air
distributed is very cold).
• Ice deposit may be hindering the
damper operation.
• The damper rod or the port damper
itself may be broken.
• The damper actuator may be
defective.
• The circuit board may be defective.
• The thermistor may be defective.
• Remove the ice.
• Inspect these parts and replace if necessary.
• Plug in the unit and select “MIN” or “MAX”. Press the door
switch and see if the port damper opens. If it doesn’t open,
feed 120V directly to the damper actuator. If the port damper
still does not open, replace the damper actuator.
• Unplug the unit. Unplug the defrost sensor wire (see J4
on electrical diagrams, Section 8). Plug the unit back in.
Select “MIN” and make sure the unit is adjusted for low
speed operation (turn all dehumidistats high speed and the
damper at the fresh air intake port should close (defrost
mode). If this does not happen, then replace the circuit
board.
• If the defrost mode works well after having disconnecting
the thermistor disconnecting the thermistor wire (above
test), this means the thermistor is probably defective. You
should replace it.
• Unplug the unit.
Disconnect the
main control
and the optional
control(s) (if need
be). Jump the OL
and OC terminals.
Plug the unit. If
the unit switches
to high speed,
replace the switch
• HVI, “Installation Manual for Heat Recovery Ventilators”, 1987 edition
• ASHRAE 1984 Systems Handbook, chapter 11, “Air Distribution Design for Small Heating and Cooling Systems”
12. TROUBLESHOOTING (CONT'D)
VE0081
OL
OC
OL
OC
13. REFERENCES
R 2000