Defrost speed-up pins Speed up the defrost timer for testing

What the display is showing

Test function on the defrost control: shorting the speed-up pins (J1) shortens the timing. On Quiet Shift-2 boards, hold the short about 5 seconds and release; with the defrost thermostat open you only see a short defrost, with it closed a full cycle runs. The same pins appear on the heat pump defrost boards described in the split-system service manual.

Applies to: N4H4/R4H4/WCH4/NXH5 heat pumps; older split heat pump defrost boards

What to do

1. Put the unit in heating and let the coil frost (defrost thermostat must be closed for a full cycle).
2. Short the J1 speed-up pins with a flat screwdriver for about 5 seconds, then release as soon as the reversing valve changes position.
3. The unit stays in defrost for the remaining cycle time or until the defrost thermostat reopens.
4. After the test reconnect anything you disconnected.

Models that show this code

5 models in KeepRite N4H4/R4H4/WCH4/NXH5 Heat Pump

Other codes on the same units

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