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CALIBRATION SEQUENCE
Sequence
CALIBRATION
K1 – Outdoor Fan (Normally Closed)
K2 – Reversing valve & RL output
K3 – Compressor Y1 out
K4 – W out
ASCD – Anti
−
short Cycle Delay
Did Defrost Terminate on Time
without Coil Temperature
greater than 35
F for 4 minutes.
With coil temperature less than 35
F, a power defrost occurs
30 minutes after power
−
up or after cooling operation. A
power defrost also occurs at return from heat pump Inactive
condition. (K1, K2, K3 = ON and K4 = OFF)
Control does not calibrate and
returns to 30
−
minute mode for
another power defrost and
calibration attempt
(K1, K2, K3 = ON and K4 = OFF)
Yes
Calibration attempted between
10 and 20 minutes following
power defrost termination
No
Was coil
temperature stable
during calibration
attempt?
Board enters power defrost after 45
minutes of accumulated
compressor run
−
time with coil
temperature less than 35
F
(K1, K2, K3 = ON and K4 = OFF)
No
Demand Mode
i = 0
Yes
Criteria to initiate
Natural Defrost Met?
NO
Initiate First Natural Defrost.
K1, K2, K3, K4 = OFF and i = 1. Set T1
(Duration 150 seconds)
Yes
Criteria to
initiate Natural
Defrost Met?
Does I = 3, T2 less
than 30 minutes, or
T2 <0.7T1?
Enter HP
Inactive / Display
Code
K3 = OFF and
K1, K2, K4 = ON
Yes
Yes
Initiate Second Natural Defrost.
K1, K2, K3, K4 = OFF and i = 1.
Set T2
(Duration 150 seconds)
No
Criteria to initiate
Natural Defrost Met?
Resume Heat Pump
Heating.
K1, K2, K4 = OFF and
K3 = ON
No
Resume Heat
Pump Heating.
K1, K2, K4 = OFF
and
K3 = ON
No
Does i = 3,
T3 less than 30
minutes, or T3
<0.7 T2?
Calibration
Sequence
A
i − Number of natural defrosts
DEFROST CONTROL (ON
−
BOARD RELAYS)
Yes
Figure 28. Calibration Sequence
