SEQUENCE OF OPERATION
PAGE 24
ENGLISH
Defrost Operation
Defrost cycle will initiate if any of three conditions are met:
Te = Defrost temperature sensor
Tao = Outdoor ambient temperature sensor
Tes = Condensation point temperature
1) Tes >= 23°F, and Te ≤ 23°F
2) 5°F ≤ Tes < 23°F, and Te ≤ Tes
3) Tes < 5°F and Te ≤ 5°F
Tes = C X Tao-a
Tao < 32°F, C = .08
Tao > or = 32°F, C = .06
a = 6
To enter the defrost mode, the compressor must have ac
-
cumulated 10 minutes of run time, and 45 minutes of accumu
-
lated run time since the last defrost cycle.
When the defrost cycle begins, the following conditions take
place:
1. The compressor will stop for 1 minute
2. The outdoor fan will continue to operate at high speed.
3. After 50 seconds, the 4-way valve will shift to the cool mode
position.
4. 5 seconds later the outdoor fan will stop.
5. After 1 minute, the compressor will start.
The outdoor unit will now defrost. The defrost cycle runs con-
tinuously for approximately 10 minutes.
The system will exit the defrost cycle if any of the following
conditions are met:
1. The condenser maintains a temperature above 45°F for 80
seconds.
2. The condenser maintains a temperature above 54°F for 5
seconds.
Upon exiting the defrost cycle, the following conditions will
take place:
1. The compressor will stop.
2. The outdoor fan will operate at high speed.
3. 50 seconds later the 4-way valve will shift to the heat mode
position.
4. 60 seconds later the compressor will start. The system
resumes normal operation.
The system resumes normal operation.
Protection Functions
Compressor High Temperature
The compressor discharge pipe sensor (exhaust temp) senses
the temperature of the refrigerant exiting the compres-
sor. The sensed temperature received from the sensor by
the control circuitry will cause the compressor frequency to
increase or decrease. (see chart below). If a temperature of
>= 230°F is sensed for 20 seconds, an exhaust overheating
protection error code will be indicated at the outdoor unit.
Abnormal stop
Decreasing the frequency rapidly (1HZ/1 second)
TTC (°F)
230
°F
212
°F
209
°F
199
°F
194
°F
Decreasing the frequency slowly (1HZ/10 seconds)
The frequency doesn’t change
Increasing the frequency (1HZ/10 seconds)
Increasing the frequency (1HZ/1 second)
Overheating Protection for Indoor Unit
A sensor monitors coil temperature in both heating and cool
-
ing modes, and causes the compressor to speed up, slow
down, or stop, according to the chart below.
Overheating Protection for Indoor Unit
Model
Increasing
Slowly
Holds Value
Decreasing
Slowly
Decreasing
Rapidly
Compressor
Stops
24K
40°C/104°F 52°C/126°F 57°C/135°F 60°C/140°F 63°C/145°F
30K
40°C/104°F 52°C/126°F 57°C/135°F 60°C/140°F 63°C/145°F
36K
40°C/104°F 52°C/126°F 57°C/135°F 60°C/140°F 63°C/145°F
Compressor Over-Current Protection
If the current draw of the compressor at start-up is greater
than the values listed on the chart below for approximately
3 seconds, the compressor will stop. After 3 minutes the
compressor will restart. If the over-current condition occurs
3 times in 20 minutes, the system will lock-out, and a code
will be indicated at the outdoor unit. It will be necessary to
remove power to the system to reset the lock-out condition.
Model
Holds
Value
Decrease
1Hz/10s
Decrease
1Hz/s
Over-
Current
Point
24K
16A
17A
18A
19A
30K
16A
17A
18A
19A
36K
16A
17A
18A
19A
