Auto Fan Control; 4-Way Valve Control; Defrosting - Pioneer WYT Series Service Manual

In heating operation, if air conditioner turn off, the indoor fan motor will run most for 30
seconds since the stop of compressor.
2) Auto fan control (heating)
In heating mode (include in "FEEL" mode), fan speed is determined by δt as the following:
RT-ST
℉)
℃(
3.5(38.3)
3.0(37.4)
1.5(34.7)
1.0(33.8)

(3) 4-way valve control

In heating mode, 4-way valve will power on ahead of compressor for 5 seconds, and cut off
for 2 minutes later than compressor . 4-way valve will not power off unless the machine to be
switched off, mode changed or on the process of defrosting.

(4) Defrosting

Defrosting is controlled by the microprocessor.
When one of the following conditions is satisfied, unit comes into defrosting:
a. Outdoor heat exchanger Temperature (OPT) is continuously less than 3℃(37.4℉) while the
unit runs for more than 40 minutes, and OPT is keeping under -6℃ for more than 3 minutes.
b. Outdoor heat exchanger Temperature (OPT) is continuously less than 3℃ (37.4℉)
meanwhile the unit runs for more than 80 minutes, and OPT is keeping under -4℃(-39.2℉)
for more than 3 minutes.
c. Outdoor heat exchanger Temperature (OPT) is continuously less than 3℃(37.4℉) while the
unit runs for more than 120 minutes,
than 3 minutes.
Before the air con comes into defrosting, compressor running frequency drop down
lower frequency firstly, then the compressor shuts down.
In defrosting, the max. frequency of compressor is F9 (a little less
frequency ). In this period all protection function are available.
Compressor
4-way valve
Expansion valve
Outdoor fan motor
In defrosting, LED showing by winking.
No matter what AC come into or out of defrosting, indoor fan motor speed
Cold Air Prevention C
While one of the following conditions is satisfied, unit comes out of defrosting and shifts to
heating mode:
a. Outdoor coil Temperature (OPT) ≥ 15℃(59℉).
b. The time of defrosting keeps for more than 10 minutes.
Air Conditioner Service Manual
δt come down
High fan
Min fan
Low fan
ON
OFF
ON
OFF
800
NORMAL
ON
OFF
50S
ontrol.
δt come up
3.5
1.5
and OPT is keeping below -2℃ (35.6℉) for more
Defrosting time ≤10Mins
10S
to a
than the highest
15S
15S
is the same as
8