Service Manual -
VMH 9/12/18/24 SU & VMH30/36S D Series
15
17
8.3 Main Protection
8.3.1 Three minutes delay at restart for
compressor
Less than
one
minute delay for the
first
time
sta
rt
-up and
a three
minute delay for others.
8.3.2 Temperature protection of compressor
top
The unit will stop working when the compressor
top temp. protector cut
s
off, and will restart after
the compressor top temp. protector restart
s
.
8.3.3 Temperature protection of compressor
discharge
Compressor discharge temp. TP
>115
°F
(239°
F
)
for 5s, compressor stops.
8.3.4 Fan speed is out of control
When Indoor fan speed
runs
too low
(300RPM) or too high
(1500RPM) for
a pre-
determined
time, the unit will stop and the LED
will display the failure
8.3.5 Inverter module protection
The Inverter module has a protection function
for
current, voltage and temperature. If these
protections happen, the corresponding code
will display on indoor unit and the unit will stop
working.
8.3.6 Indoor fan delayed open function
When the unit starts up, the louver will be active
immediately and the indoor fan will open 10
s
econds
later.
If the unit runs in heating mode, the indoor fan
will also
be
controlled by anti-cold wind
function.
Fan will turn on, low speed, at 87°F
coil temperature. Fan will switch to high speed
at 114°F coil temperature.
8.3.7
C
ompressor preheating functions
Preheating permitting condition
:
W
hen T4
(
outdoor ambient temperature
)
<
3
°
C
(
37.4
°
F
),
the preheating function
w
ill be
activated.
8.3.8 Zero crossing detection error
protection
If AC detects time interval is not correct for
continuous 240s, the unit will stop and the LED
will display the failure. The correct zero
crossing signal time interval should be between
6-13ms.
8.3.9 Sensor protection at open circuit and
breaking disconnection.
When there
i
s only one temperature sensor in
malfunction, the air conditioner will keep
working but show the error code, in case of any
emergency use.
When
there
is
more
than
one
temperature
sensor
in malfunction, the air conditioner will
stop working
.
8.3.10 Refrigerant leakage detection
This function is only active in cooling mode. It
can
better
prevent
the
compressor
being
damaged by refrigerant leakage or
compressor
overload.
Open condition:
When
compressor is active, the value of the
coil t
emperature
of evaporator T2 has no
change, or very little change
.