Airwell YAZE218, Service Manual

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12—9 | SM YAZE218 1-A.2 GB
12—TROUBLESHOOTING
12.4.4 Checking the Reverse Valve (RV)
The RV has two parts, Solenoid and valve.
Solenoid - Running in heating mode, check the voltage between two pins of reverse valve
connector, normal voltage is 230VAC. if no power supply to RV, Check RV operation with direct
230VAC power supply, if OK, replace outdoor controller.
Valve — if RV solenoid is OK (as above) but still no heating operation while compressor is On,
replace the valve.
12.4.5 Checking the electrical expansion valve (EEV)
The EEV has two parts, drive and valve.
When Outdoor unit is powered on, EEV shall run and have click and vibration.
For assuring the problem is of the EEV parts, perform the installation test. check (11.6) and if fails
and no other indications in the diagnostics, than the problem is with the EEV (one or more).
Drive - a step motor; ringed on the valve. Check the drive voltage, should be12VDC.
Valve – if drive is OK (as above) but still the indoor unit perform no conditioning replace the valve
(no need to take out the refrigerant, just pump down and shut off the main valves).
12.4.6 Checking the thermistors
Check Thermistor connections and wiring — Repair if needed.
Check Thermistor resistance — between 0ºC and 40ºC should be between 35K Ω and 5K Ω .
12.4.7 Checking the communication
Change to Stand-by or Power OFF and re-start - If the fault is still “Active” check Indoor to Outdoor
Communication wiring and grounding connections (should be less than 2.0 Ω ) — Repair if needed.
If IDU failure — replace IDU controller that does not respond. If ODU failure — replace ODU.
12.4.8 Checking for electromagnetic interference (EMC problems)
12.4.8.1 EMC troubles to the A/C unit
Locations most susceptible to noise:
1. Locations near broadcast stations where there are strong electromagnetic
waves.
2. Locations near amateur radio (short wave) stations.
3. Locations near electronic sewing machines and arc-welding machines.
Trouble:
Either of the following trouble may occur:
1. The unit may stop suddenly during operation.
2. Indicator lamps may icker
Correction:
The fundamental concept is to make the system less susceptible to noise (insulate for
noise or distance from the noise source):
1. Use shielded wires.
2. Move unit away from the noise source.