Power off unit totally - 240V & 24V
- Pull unit disconnect.
- Disconnect high voltage power to air handler
Record positions and colors of original wiring.
Remove old defrost control board.
- Phillips screws in corners.
Install replacement board, utilizing original screws.
Set the Defrost Curve Selection Jumper to the proper position.
- For any new setting to take effect 24V power must be removed and reapplied.
Re-attach wiring and power-up the unit - 240V & 24V.

DEFROST CURVE SELECTION

When the control board is replaced, the jumper MUST be placed in a numbered position or the unit will not function. Select the proper jumper position.

Position #1 is recommended for reciprocating compressors.
Position #2 is recommended for R410a scroll compressors.
Do not use Position #3 or 4 unless instructed to do so by technical support.

If the jumper is missing or left in the P position, the replacement control will not energize the compressor.

When the jumper position is changed, the control will not act upon the jumper changes until the thermostat calls are de-energized or power (24VAC) to the control is cycled.

The control will display the active defrost curve using the X/L terminal when the heat pump is operating in a defrost cycle that has been forced using the TEST input. For instance, the X/L output will be energized with two flashes when defrost curve 2 is active.

COMPRESSOR DELAY

When Defrost Jumper Position #2 is selected the compressor is shut down for 30 seconds entering and exiting defrost mode.

The delay is present in a normal defrost but IS NOT present when the TEST pins are shorted to initiate a defrost cycle.

Use Position #2 for R410a units.