Lennox XP21 Series Installation Instructions Manual page 36

MULTI−FUNCTION TEST PINS (E33)
Placing the jumper on the field test pins (E33) using a specific sequence allows the technician to:
S
Clear short cycle lockout
S
Clear five−strike fault lockout
S
Cycle the unit in and out of defrost mode
S
Manually place the unit in defrost mode to clear the coil
When Y1 is energized and 24V power is being applied to the heat pump control (A175), a test cycle can be initiated by placing a jumper on the heat
pump control's TEST pins for 2 to 5 seconds. If the jumper remains on the TEST pins (E33) for longer than five seconds, the heat pump control will
ignore the jumpered TEST pins and revert to normal operation.
The heat pump control will initiate one test event each time a jumper is placed on the TEST pins. For each TEST the jumper must be
removed for at least one second and then reapplied.
Place a jumper on TEST pins for
longer than one second but less
than two seconds.
Clears any short cycle lockout and
five strike fault lockout function, if
applicable. No other functions will be
executed and unit will continue in the
mode it was operating.
If in COOLING Mode
No further test mode operation will be
executed until the jumper is removed
from the TEST pins and reapplied.
NOTE Heat pump control cannot be force into
defrost mode when the ambient temperature input
from the RT13 sensor is above 65ºF (18ºC).
NOTE If ambient or coil fault is detected, the board
will not execute the TEST mode.
506601−01
Y1 Active
Clears any short cycle lockout and
five strike fault lockout function, if
applicable.
ACTIVE
If in DEFROST Mode
The unit will terminate defrost and
enter HEAT MODE un−calibrated
with defrost timer set for a maximum
34 minute test.
Figure 28. Heat Pump Control's Multi−Function Test Pins (E33)
Place a jumper on TEST pins for
more than two seconds.
O Line Status
If jumper on TEST pins remains in
place for more than five seconds.
The unit will return to HEAT MODE
un−calibrated with defrost timer set
for 34 minutes.
Page 36
INACTIVE
If in HEATING Mode
If no ambient or coil sensor fault
exist, unit will go into DEFROST
MODE.
If ambient or coil faults exist (open or
shorted), unit will remain in HEAT
MODE.
If jumper on TEST pins is removed
before a maximum of five seconds.
The unit will remain in DEFROST
MODE until termination on time or
temperature.