Initiating Forced Defrost Operation; Defrosting Time Flowchart; Frequency Control And Compressor Discharge Line Temperature; Frequency Control When There Is Ct Over-Current Protection - Haier 2U18MS2VHB Service Manual

Ductless multi-split heat pump, outdoor/indoor, wall mount - highwall, 2'x2' compact cassette, 3'x3' large cassette, slim duct, mid-static ducted, medium static ducted, console
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Initiating Forced Defrost Operation

The system can be placed into a forced defrost cycle from the
wired controller. The system will remain in defrost until sensor
Te has sensed 53.6°F for at least 1 minute or until the defrost
cycle has reached 10 minutes total runtime.
A forced defrost cycle can be initiated with the compressor
off. The system will enter a 3 minute time delay prior to
energizing the compressor.

Defrosting Time Flowchart

10.2.7 Defrosting operation flow chart:
beginning
fixed frequency
indicated FQY
60s
compressor
0HZ
5s
outdoor motor
ON
OFF
4-way valve
ON
OFF
450-pulse
all EEVs
auto open angle
all indoor motors ON
OFF
Frequency Control and Compressor Discharge Line
Temperature
If the temperature of the discharge line gets too high, and
the EEV adjustment cannot correct the problem, the ECU will
make frequency adjustment to the speed of the compressor
10.2.8 Frequency control when compressor discharge temp.(Td) is too high
in an attempt to cool it down. The chart here shows the
Purpose: make compressor frequency control if the discharging temp. is too high, to lower the discharging
adjustment steps versus the discharge line temperature.
temp. efficiently and ensure the system can run normally.
Multi:
If keeping for 10s, the unit stops, 3 minutes later, the unit can
re-startup. If in 60 minutesthe unit occurs alarm for 3 times, the
failure can be eliminated.
248 ℉
Reduce FQY rapidly 2HZ/S
239 ℉
Reduce FQY rapidly 1HZ/S
230℉
Reduce FQY slowly 1HZ/10S
221℉
Remain FQY
212℉
Increase FQY slowly 1HZ/10S
203℉
end
defrosting FQY 80 Hz(E )
60s
soft startup
0HZ
send defrosting signal to indoor
Auto
15s
450-pulse
350-pulse(E)
auto open angle
anti-cold air fun ction
69
OUTDOOR TECHNICAL OVERVIEW
Operations
Frequency Control when there is CT Over-current
Protection
10.2.8.
1.0 I
0.95I
0.93I
0.90I
0.88I
0.85I
10.2.9.
10.2.8.

High Pressure Protection

When the input signal of pressure switch is low level: 0 for 1 minute, that shows high pressure
If abnormally high refrigerant circuit condensing pressure is
1.0 I
detected, the high pressure switch will open. The outdoor unit
code to indoor. Meanwhiel, by controling the max. condensating temp.Tc(cooling) or module temp. sensor(TmAVE),
0.95I
will initiate an Error Code and stop compressor operation. If
please confirm as follow
the system pressure drops enough to re-close the switch the
0.93I
system will re-start. If the failure occurs 3 times, the system
0.90I
will lock out and display the appropriate Error Code.
0.88I
High condensing temperature can also cause high pressure.
156℉
The ECU will monitor the temperature of the condensing coil
0.85I
154℉
in both heating and cooling modes of operation. Frequency
adjustments will be made to the compressor speed in an
151℉
10.2.9.
attempt to manage high pressure that can be caused by dirty
When the input signal of pressure switch is low level: 0 for 1 minute, that shows high pressure
147℉
condensing coils and high heat loading. The chart below shows
the ECU frequency response at high condenser temperatures.
144℉
code to indoor. Meanwhiel, by controling the max. condensating temp.Tc(cooling) or module temp. sensor(TmAVE),
(Indoor Coil Heat Mode, Outdoor Coil Cool Mode)
please confirm as follow
140℉
10.2.10.
(1) When compressor is running, if output signal of low pressure switch is low level: 0 for 1
156℉
154℉
(2) When compressor no running, if output signal of low pressure switch is low level: 0 for 30
151℉
147℉
144℉
140℉
10.2.10.
(1) When compressor is running, if output signal of low pressure switch is low level: 0 for 1

Low Pressure Protection

The system low pressure switch is normally closed. The
(2) When compressor no running, if output signal of low pressure switch is low level: 0 for 30
switch will open when the refrigerant pressure gets too low.
Typical causes are refrigerant leaks/undercharging and low
evaporator heat loading. The system will auto re-start if the
switch re-closes after opening. If the switch opens 3 times in
60 minutes of running, the system will display an error code.
The low pressure switch is checked even when the system is
off. This protects the compressor against operating with a
great loss of refrigerant when the system has been off for a
long time.
Stop immediately, if abnormal stop 3 times in 1 hour, the
unit will stop and alarm.
Reduce FQY rapidly 2HZ/S
Reduce FQY rapidly 1HZ/S
Reduce FQY slowly 1HZ/10S
Remain FQY
Increase FQY slowly 1HZ/10S
Stop immediately, if abnormal stop 3 times in 1 hour, the
unit will stop and alarm.
Reduce FQY rapidly 2HZ/S
Reduce FQY rapidly 1HZ/S
Keep for 5 seconds, stop to alarm, after 3-minute standby, the
Reduce FQY slowly 1HZ/10S
unit can restartup. In 60 minutes it occurs 3 times continously,
unit will stop to alarm and the failure can be resumed after being
Remain FQY
electrified again.
Reduce FQY rapidly 2HZ/S
Increase FQY slowly 1HZ/10S
Reduce FQY rapidly 1HZ/S
Reduce FQY slowly 1HZ/10S
Remain FQY
Increase FQY slowly 1HZ/10S
Keep for 5 seconds, stop to alarm, after 3-minute standby, the
unit can restartup. In 60 minutes it occurs 3 times continously,
unit will stop to alarm and the failure can be resumed after being
electrified again.
Reduce FQY rapidly 2HZ/S
Reduce FQY rapidly 1HZ/S
Reduce FQY slowly 1HZ/10S
Remain FQY
71
Increase FQY slowly 1HZ/10S
71
B-13

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