Sequence Of Operation; Modes Of Operation - Carrier 40GXC Service Manual

Compressor Over Current Protection
Over current protection can result due to any of the following:
S The ambient temperature is too high
S Locked rotor on the compressor
Blockage in the refrigeration circuit (capillary tubes for
S
example)
S Outdoor air is blocked or restricted
The compressor current is monitored continuously. Based on the
amp draw measured, the microprocessor will allow the compressor
to increase frequency, maintain frequency, drop frequency, and
eventually de- -energized the compressor if excessive amps are
experienced.
Frequency Frequency
Compressor Compressor
Outdoor Fan Outdoor Fan
Indoor Fan Indoor Fan
I I D I D
II M
Fig. 17 – Overcurrent Protection
IPM Module Protection
This can be caused by any of the following:
S Loss of cooling to the heat sink
S High ambient temperatures
S Low voltage
S Loose screws fastening the board to the heat sink
When this occurs, H5 is displayed on the LED display on the front
panel of the indoor unit.

SEQUENCE OF OPERATION

Interface
A wireless remote control, supplied with the unit, is the interface
between the fan coil and the user. The wireless remote control has
the following characteristics:
S Dedicated controllers for _C or _F. Each indoor units
comes with two remotes that are clearly labeled for the
appropriate temperature scale.
S The remote control range is from 61_F (16.1_C)to 86_F
(30_C).
S The same remote is used for both cooling only and heat
pump units
S The wireless remote control range is 25 ft (7.6 m).
S The same remote can be used to control more than one
unit.
S If the remote control is lost, damaged, or the batteries are
exhausted, the system can be operated using the manual
button located under the front panel
Current Current 9K 9K 12K 12K
I I I I 6 6 7 7
I M I M 7 7 8 8
I D I D 8 8 9 9
I O I O 9 9 10 10
I O I O
A09349

MODES OF OPERATION

The units have five main operating modes:
1. Fan only
2. Cooling
3. Heating (heat pump only)
4. Auto
5. Dry (Dehumidification)
The units also have the manual mode that allows the unit to be
operated without the remote control.
Fan Only Mode
In this mode, the system circulates the room air without changing
the room air temperature.
Cooling Mode
In this mode, the system cools and dries the room air with the fan
running continuously, either at a selected fan speed or Auto fan
speed. The fan runs even when the compressor cycles off. This
feature enhances room comfort and efficiency of the system.
Compressor, Outdoor Fan Operations, and Indoor fan
Operation
As shown below, the compressor and outdoor fan motor cycle on
and off based on the conditions of the set point and the room
temperature. The indoor fan runs continuously.
T T ≤ T ≤ T - 3.6°F - 3.6°F
amb amb S S
T T + 1.8°F + 1.8°F
S S
T T
S S
T T - 3.6°F - 3.6°F
S S
Compressor ≥ 3 min ≥ 3 min
30S 30S
Outdoor Fan
Indoor Fan
Fig. 18 – Cooling Mode
Indoor Fan Operation - - Cooling
When in cooling mode, the fan runs continuously either at the
chosen set speed, or in Auto mode, where the speed is determined
by the microprocessor based on the difference between the room
temperature and the temperature set point as shown below:
High
Medium
Low
T T
S S
Fig. 19 – Auto Fan - - Cool Only Mode
13
T T ≥T ≥T +1.8 °F +1.8 °F
amb amb S S
Compressor
matches load
30S 30S
A09249
T T + 3.6°F + 3.6°F
S S
A09250