Hps/Lps Detection Function; Electronic Expansion Valve Control; Abnormally High Discharge Pipe Temperature - Daikin Skyair FHC35K Service Manual

Function Details
5.2.3

HPS/LPS Detection Function

If either HPS or LPS are actuated while the compressor is running, the compressor stops and begins
standing by for 3 minutes. (Depending on operation conditions, even if LPS is actuated the compressor
may not go OFF in some cases)
If this movement is detected an additional 5 times from the time it is first detected to until turned off by
remote controller, operation is stopped due to malfunction.
5.2.4

Electronic Expansion Valve Control

Electronic
About 10 seconds after turning on the power supply, the electronic expansion valve's opening is tightened
Expansion 520 pulses to close it all the way.
Valve Initialize
Discharge Pipe
The optimal discharge pipe temperature for present operation is calculated according to indoor unit heat
Temperature exchange temperature, outdoor unit heat exchange temperature, and outdoor air temperature, with the
electronic expansion valve being controlled so that the discharge pipe temperature approaches the optimal
discharge pipe temperature.
Optimal discharge pipe temperature - discharge pipe temperature <0°C (superheat operation)
→ Motor operated valve is opened
Optimal discharge pipe temperature - discharge pipe temperature >0°C (wet operation)
→ Motor operated valve is closed.
5.2.5

Abnormally High Discharge Pipe Temperature

If discharge pipe high temperature thermostat OFF or T2 (discharge pipe thermistor) disconnection is
determined 6 times or wet operation protection control is determined, operation stops due to abnormal
discharge pipe temperature.
Wet Operation Cooling : Discharge pipe temperature < outdoor unit heat exchanger temperature +10°C
Protection Control
15 minutes in succession
Heating : Discharge pipe temperature < indoor unit heat exchanger temperature +10°C
15 minutes in succession
and the electronic expansion valve openning is 50 pulses or less.
5.2.6 Discharge Pipe High Temperature Thermostat OFF Control
If discharge pipe temperature T2 remains above 123.5°C for 100 seconds in succession, or above 140°C
for 20 seconds in succession, the thermostat is turned OFF.
5.2.7 T2 Disconnection Thermostat OFF Control
If the discharge pipe thermistor is determined to be disconnected from the piping 5 minutes after the
compressor starts, the thermostat is turned OFF.
5.2.8 Lack of Gas Malfunction
When the thermostat is turned OFF due to abnormally high discharge pipe temperature, lack of gas
malfunction occurs if the opening of the solenoid valve is 450 pulses or more. Operation however does not
stop due to lack of gas. Lack of gas malfunction can be checked by remote controller inspection.
5.2.9 Emergency Operation
„ No signal is transmitted between the indoor and outdoor units.
„ Emergency operation is not possible if the motorized valve has a malfunction.
„ Switches on the control printed circuit boards of both indoor and outdoor units are used for an
„ In heating operation, defrosting operation is activated once every hour.
66
emergency operation.
The outdoor unit's control printed circuit board is used for the changeover of the cooling/heating mode.
Explanation of Function Operation
Si-71A