Temperature Sensors; Defrost Operation; Protection Functions; 1. Ttc High Temperature Protection - Haier HSU09VHG(DB)-W Service Manual

Temperature sensors

Four temperature sensors located in the outdoor unit provide
temperature information to the outdoor unit main board for
control of the system during dry mode.
The outdoor ambient temperature sensor provides the
temperature of the air drawn into the condenser coil of the
outdoor unit.
The defrost temperature sensor provides the temperature
sensed at the output of the condenser coil.
The suction line temperature sensor provides the tempera-
ture sensed at the incoming suction line pipe.
The compressor discharge sensor provides the temperature
sensed at the discharge pipe of the compressor.
To stop dry mode, press the power button to turn the system
off, or change to another mode.

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
The minimum time interval between defrost cycles is 45
minutes.
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 continuously 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
PAGE 32
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.

1. TTC high temperature protection

The compressor discharge pipe sensor (exhaust temp)
senses the temperature of the refrigerant exiting the com-
pressor. 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.
TTC (°F)
230
°F
212
°F
209
°F
199
°F
194
°F

2. Overheating protection for indoor unit

The indoor tube sensor senses the temperature of the indoor
heat exchanger.
If the temperature sensed is greater than 133°F, the com-
pressor frequency will decrease to prevent overheating of
the heat exchanger.
If Tc >= 133°F for more than 10 seconds, the compressor will
stop and an error code will be indicated at the outdoor unit.
If the compressor is off for 3 minutes and Tc <118°F, the com-
pressor will restart.
If the temperature sensed is lower than 118°F, the protection
function is canceled.
SEQUENCE OF OPERATION

Protection Functions

Abnormal stop
Decreasing the frequency rapidly (1HZ/1second)
Decreasing the frequency slowly (1HZ/10 seconds)
The frequency doesn't change
Increasing the frequency (1HZ/10 seconds)
Increasing the frequency (1HZ/1second)