Forced defrost Forced defrost (short the defrost pins)

What the display is showing

Test function that starts a defrost cycle by hand. A full defrost runs only if the coil is at 32 F / 0 C and the outdoor air is under 50 F / 10 C; otherwise only an abbreviated 30-second defrost happens. Quiet Shift-2 delays are included when that mode is on. The HK32EA003/008 defrost boards use a similar speed-up jumper (J1): short for 5 seconds then release; with the defrost thermostat open a short defrost of about 30 seconds results, with it closed a full cycle runs.

Applies to: Carrier single-stage communicating heat pump; HK32EA003/008 defrost boards

What to do

1. Short the two-pin FORCED DEFROST header for 5 seconds, then release.
2. On HK32EA003/008 boards, short the speed-up pins (J1) with a screwdriver for 5 seconds and release.
3. On the Infinity single-stage communicating heat pump the same can be commanded from the user interface.

Other codes on the same units

• 53 Outdoor air temperature sensor fault
• 55 Outdoor coil temperature sensor fault
• 56 OAT / coil thermistor out of range
• 73 Contactor shorted
• 83 Low pressure lockout (4 hours)
• 84 High pressure lockout (4 hours)
• COMM LED Green COMM LED on - communicating
• ON Amber STATUS LED on solid - standby