AUX ASW-H09B5B4/FAR3DI-C3, Service Manual

Page: 56 / 101

53
(22) P4 –Refrigeration Overload Protection
Explanation of
error
Cause: Outdoor coil sensor senses excessive temperature, prevents
compressor from overloading, and reduces frequency.
Inspection path: the system is dirty or blocked
→
the condenser is
dirty
→
Outdoor Unit coil sensor is faulated
→
AC motor not running
→
failure of divider resistance of controller
Tools required
for inspection
Multimeter and pressure gauge
Frequent
problematic part
Coil sensor, condenser and outdoor unit controller
Inspection
procedure and
key points
1. Check the coil sensor with a multimeter to see if the resistance value
is normal (20KΩ standard sensor, 25
℃
)
2. Use a pressure gauge to detect system pressure. If the system
pressure is high, it may cause Indoor Unit dirty blockage or poor
Outdoor Unit heat transfer, which may lead to high coil temperature.
3. Observe whether the speed of AC motor is too low, which leads to
poor heat transfer and high coil temperature.
4. Use a multimeter to check whether the voltage dividing resistance of
temperature sensor circuit of Outdoor Unit controller coil is abnormal.
If you don't know how to measure it, try to replace the Outdoor Unit
controller to check whether it returns to normal state.