The control stores the 10 most recent fault codes in memory.
The codes are stored even when power is removed from the control and will remain in memory until they are manually cleared from the control.
All codes are time stamped and stored in order of occurrence.
The control stores only one identical fault code during the same series of events. For example, if two or more low temperature cutout faults occur sequentially without another fault occurring in between the low temperature cutout faults, the control only stores the low temperature cutout fault once.
The stored faults can be displayed by pressing the PUSH BUTTON for two to six seconds, without a call for compressor operation.

Status Code Display
LED	Segment 1	Segment 2	Description
Off			No power to control
2s on 2s Off			Normal operation - No call for compressor
0.1s On 0.1s Off	d	5,4,3,2,1	COOLING Short-cycle delay timer
0.1s On 0.1s Off	d	5,4,3,2,1	HEATING Short-cycle delay timer
On	C	1	COOLING 1st Stg Compressor Operation
On	C	2	COOLING 2nd Stg Compressor Operation
On	H	1	HEATING 1st Stg Compressor Operation
On	H	2	HEATING 2nd Stg Compressor Operation
On	A	1	Aux Heat 1 (below BP)
On	A	2	Aux Heat 2 (below BP)
On	d	r	COOLING Demand Response (Utility input)
On	d	r	HEATING Demand Response (Utility Input)
On	E	1	Emergency Heat Stg 1
On	E	2	Emergency Heat Stg 2
On	o	r	Oil Return
On	d	d	Demand Defrost
On	d	c	Calibration Defrost
On	t	d	Time & Temperature Defrost
On	F	d	Forced Defrost

Operational Fault Codes
LED	Segment 1	Segment 2	Description	Control Response
On	0	0	Control Failure	None
On	0	1	High-pressure switch (not in lockout yet)	None
2 flash	0	2	2 High-pressure faults in 6 hours	Soft Lockout
3 flash	0	2	4 High-pressure faults in 12 hours	Hard Lockout
2 flash	0	3	2 DEFROST High-pressure faults in 6 hours	Soft Lock
3 flash	0	3	4 DEFROST High-pressure faults in 12 hours	Hard Lockout
2 flash	0	4	Low-pressure switch fault	Soft Lockout
3 flash	0	4	4 Low-pressure faults in 12 hours	Hard Lockout
On	0	5	LTCO Active	None
On	0	6	Low Voltage < 19.2VAC	None
On	0	7	Low Voltage < 16VAC	None
On	0	8	Pipe Freeze Protection	None
On	0	9	Outdoor Sensor shorted in Cooling	ODF operates at Max
On	0	9	Outdoor Sensor shorted in Heating	None
2 flash	0	9	Outdoor Sensor shorted in Heating	Soft Lockout
On	1	0	Outdoor Sensor Open in Cooling	ODF operates at Max
On	1	0	Outdoor Sensor Open in Heating	None
2 flash	1	0	Outdoor Sensor Open in Heating	Soft Lockout
2 flash	1	1	Coil Sensor Shorted	Soft Lockout
2 flash	1	2	Coil Sensor Open	Soft Lockout
2 flash	1	3	Discharge Sensor Shorted	Soft Lockout
2 flash	1	4	Discharge Sensor Open	Soft Lockout
On	1	5	Discharge Temp > 263 F	None
2 flash	1	5	Discharge Temp > 263 F (3 times)	Soft Lockout
3 flash	1	5	Discharge Temp > 263 F (12 times)	Hard Lockout
On	1	6	Discharge Temp < 90 F	None
2 flash	1	6	Discharge Temp < 90 F (3 times)	Soft Lockout
3 flash	1	6	Discharge Temp < 90 F (12 times)	Hard Lockout
2 flash	1	7	Bonnet Sensor Shorted	Soft Lockout

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Article ID: 717

Last updated: 31 Mar, 2023

Revision: 5

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YZT Status Codes / Fault Codes

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