Outdoor Unit Control - Daikin GYEQ20AN Service Manual

SiAUY361411EA

2. Outdoor Unit Control

• If the outdoor air temperature drops to -10°C or lower during cooling, this function is activated
• After the outdoor unit is stopped, this function inhibits operation from being started again for 4
When the discharge temperature is 110°C or higher, this function is activated to reduce the
engine speed steps in decrements. (1 step every 5 minute)
This function is cancelled when the temperature falls to 100°C or lower during cooling or to
107.5°C or lower during heating.
When the cooling water temperature is 100°C or higher, this function is activated to reduce the
engine speed steps in decrements. (1 step every 1 minute)
This function is cancelled when the cooling water temperature falls to 95°C or lower.
When the cooling water temperature is 90°C or higher, this function is activated to increase the
fan speed steps in increments.
This function is cancelled when the cooling water temperature falls to 85°C or lower.
If a severe backflow of fluid occurs while the outdoor unit is running, this function is activated to
perform bypass operation by closing electronic expansion valves EV1 and EV2, maintaining the
engine speed steps at the lower limit, opening electronic expansion valve EV3, and opening
solenoid valve SV1. When the water temperature rises, the function heats the refrigerant. Once
it has finished heating the refrigerant, the function performs "pump down" operation, temporarily
stops the outdoor unit and then restarts it. If the function cannot finish heating the refrigerant
within 40 minutes, an abnormal stop occurs.
Before the outdoor unit is stopped, this function is activated to close the electronic expansion
valves (EV1 to EV7, 3A, 3B) and run the outdoor unit in pump down mode for 6 minutes at
maximum in order to gasify the refrigerant.
When the user attempts to stop the outdoor unit before reaching the minimum operating time,
this function is activated to run the outdoor unit in pump down mode till the minimum operating
time elapses.
When the outdoor unit receives a contact input signal from the snow sensor, which is enabled
through the memory switches, this function is activated to intermittently run the fans after the
specified time period
∗ This time setting can be configured using the memory switches.
Available with a cooling/heating outdoor unit, this function switches the outdoor unit among
different modes (cooling, concurrent cooling/heating, heating, and so on) depending on the
indoor cooling air conditioning and heating air conditioning loads.
Control and Functionality
(Cooling/heating) "Inhibit" control function
to inhibit the cooling indoor unit only from operating.
If the outdoor air temperature rises to 30°C or higher during heating, this function is activated
to inhibit the heating indoor unit only from operating. When an indoor unit "Thermo ON" signal
is received after the outdoor unit has been stopped by this function, the function intermittently
runs the fans in a cyclic pattern: ON for 5 minutes and OFF for 30 minutes.
minutes.
(Cooling/heating) "Avoid Excessive Discharge Temperature" control function
(Cooling/heating) "Avoid Excessive Cooling Water Temperature" control function
(Cooling/heating) Oil separator heating control function
(Cooling/heating) "Pump Down" control function
(Cooling/heating) "Ensure Minimum Operating Time" control function
(Cooling/heating) "Snow Sensor Outdoor Fan" control function
∗
elapses, whether or not the outdoor unit is currently running.
(Cooling/heating) "Mode Change" control function
Outdoor Unit Control
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