Carrier 40MAQ Series - Control System; Compressor Operation in Cooling Mode; HEATING MODE

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CONTROL SYSTEM
The unit is equipped with a microprocessor control to perform two
functions:
1 Provide safety for the system
2 Control the system and provide optimum levels of comfort
and efficiency
The main microprocessor is located on the control board of
outdoor unit. Outdoor and indoor units have thermistors used to
monitor the system operation to maintain the unit within acceptable
parameters and control the operating mode.
Indoor fan speed
Maximum frequency
High speed/turbo function No limit
Silent mode Fixed
If users switch on AC by remote controller, the compressor will run
at the Fmax frequency for 7 minutes according to the outdoor
ambient temp. During the 7 minutes, the frequency limitation is
active. 7 minutes later, the compressor running frequency will be
controlled as shown below. While the zones of A, B, C… are
corresponding to different compressor running frequency.
Fig. 20 – Zones
NOTE: Whe n AC is in “hold” zone for 3 minutes, the compress or
frequency will rise to the higher level.(frequency will increase twice
at most).
Fig. 21 – Zones
I3COOL, I2COOL, I1COOL mean different running current value.
S Off: Compressor stops.
S Decrease: Decrease the running frequency to the lower
level.
S Hold: Keep the current frequency.
S Resume: No limitation for frequency.
NOTE: When AC is in “hol d” zone for 3 mi nut es, the compr essor
frequency ri ses to the higher leve l . (Freque nc y inc reases twice a t
most) .
When T1 - Ts stays in the same temperature zone for 3 minutes, the
compressor runs according to the following rules:
1 Increase the frequency to the higher level until F10.
2 Keep the current frequency.
3 Decrease the frequency to the lower level until F1.
4 Run at F1 for 1h.(if T1 - Ts-
T>42.8_F(6_C), the
compressor will stop).
Meanwhile, the compressor running frequency is limited by the
current.
Fig. 22 – Running frequency
Fig. 23 – Indoor fan running rules
In the cooling mode, indoor fan runs all the time and the speed can
be selected as high, medium, low, auto and silent mode.