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Controls
Control Modes
Based Control
Compressor Control
When the unit comes on in heating or cooling mode; the indoor fan will run for a short time before the
compressor starts. Under different modes, the compressor can only be stopped after running for some time
(special cases excluded). This is to protect the compressor from short-cycling. Once the compressor has
stopped, it cannot be operated right away due to a time delay.
EXV Control
The electric expansion valve will reset when the unit is first started. During the process, the expansion valve
will make clicking sounds. The valve will open to a predetermined step before the unit starts in cooling or
heating mode.
Outdoor Fan Control
This series heat pump has two types of outdoor units: one with a single fan and the other with dual fans. The
outdoor fan can run at the highest level 10 and the lowest level 1. By controlling the speed of outdoor fan, the
unit can achieve cooling at low temperature and heating at high temperature. The outdoor unit fan will not
run while the system is set to indoor fan mode only.
4-way Valve Control
The 4-way valve will be energized in heat mode (after a brief time delay) on start-up. The 4-way valve will be
de energized during cooling and defrost modes.
The 4-way valve will continue to be energized in heating mode after the unit stops. This occurs so the valve
will not inadvertently shift into cooling position.
There must be adequate differential pressure for the 4-way valve to function properly.
Special Control
Defrosting Control
Defrosting will start when the temperature sensed by outdoor tube outdoor coil temperature drops below
a calculated value. The 4-way valve will switch to the cooling mode, and outdoor and indoor fan will both
stop. The defrost cycle will terminate when the outdoor coil temperature reaches the calculated defrost
termination value. The 4-way valve will switch back to the heating mode, and the compressor and outdoor
fan(s) will restart.
Oil Return Control
The system will enter oil return mode if the compressor has been running at low frequency for an extended
period. The system will exit oil return mode in about 5 minutes.
Protection Control
High Pressure Protection Control
The system will shut the compressor down if the high pressure switch is open continuously for a short period
of time and display an E1 error code. The compressor will restart after the switch closes for a short period
of time. The system will shut the compressor down if the switch opens again within a predetermined time
interval. The system will remain in a locked out condition until the power is cycled to the unit.
6
CONNECT SERIES SERVICE MANUAL
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Troubleshooting
