Electronic Functions - Carrier DHMVHA Service Manual

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ELECTRONIC FUNCTIONS

Main Protection
When the indoor fan speed remains too low (300RPM) for a certain
amount of time, the unit stops and the LED displays the failure.
Indoor Fan Delayed Open Function
When the unit starts up, the louver becomes active immediately and the
indoor fan opens 7 seconds later. If the unit runs in the HEATING mode, the
indoor fan falls under the control of the anti-cold wind function.
Zero Crossing Detection Error Protection
If the unit detects that the time interval is not correct for a continuous
period of 240s, the unit stops and the LED displays the failure. The
correct zero crossing signal time interval should be between 6-13ms.
Sensor Protection at Open Circuit and Breaking
Disconnection
When there is only one malfunctioning temperature sensor, the air
conditioner keeps working however an error code appears, in the event of
emergency use. When there is more than one malfunctioning temperature
sensor, the unit stops working.
Operation Modes and Functions
FAN Mode
1. Outdoor fan and compressor stop
2. Temperature setting function is disabled, and no setting temperature
appears
3. Indoor fan can be set to high/med/low/auto
4. The louver operates the same in the COOLING mode
5. Auto fan
Fig. 7 — Auto Fan
COOLING Mode
Indoor Fan Running Rules
In the COOLING mode, the indoor fan runs constantly and either speed
(high, medium, low or auto) can be selected. When the setting
temperature is reached, if the compressor stops running, the indoor fan
motor runs at the minimum or setting speed. The indoor fan is controlled
by the rules shown in Fig. 8.
Setting fan
T1-Td (°F)
speed
H
M
L
Fig. 8 — Indoor Fan Running Rules
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
The AUTO fan is controlled by the rules shown in Fig. 9.
Evaporator Temperature Protection
When the evaporator temperature is lower than the setting value, the
compressor stops.
HEATING Mode
Indoor Fan Running Rules
When the compressor is on, the indoor fan can be set to high/med/low/
auto/mute. When the indoor unit coil temperature is low, the anti-cold air
function starts and the indoor fan motor runs at a low speed and the speed
can not be changed. When the temperature is lower than the setting value,
the indoor fan motor stops.
When the indoor temp reaches the setting temperature, the compressor
stops and the indoor fan motor runs at the minimum or setting speed (the
anti-cold air function is valid). The indoor fan is controlled by the rules
shown in Fig. 10.
Setting fan
Auto Fan Action in HEATING Mode
Actual fan speed
8
Fig. 9 — Indoor Fan Running Rules
T1-Td
speed
H
M
L
Fig. 10 — Indoor Fan Running Rules
T1
a
b
c
d
e
Fig. 11 — Auto Fan Action in HEATING Mode
Actual fan speed
H- H-=H-G)
H =H
H+(H+=H+G)
M-(M-=M-Z)
M(M=M)
M+(M+=M+Z)
L-(L-=L-D)
L(L=L)
L+(L+=L+D)