Bosch ODU Split 6 - Electronic Expansion Valve (EEV)

Check system parameters
Split ODU – 6 720 817 722 (2015/06)
36
5 Check system parameters
6 Electronic expansion valve
Fig. 34 EEV driving circuit
Output pulse sequence
– In valve close state: 1 -->2 -->3 -->4 -->5 -->6 -->7 -->8 -->1
– In valve open state: 8 -->7 -->6 -->5 -->4 -->3 -->2 -->1 -->8
1. If EEV open angle does not change, all of output phase will be OFF.
2. If output phase is different or continuously in the ON state, motor will
not operate smoothly and start vibrating.
Temperature difference between inlet and outlet
depends on water flow rate and exchange-surface of the
heating system.
Symptom Remark
No temperature difference between water inlet and outlet
Power consumption is low (<80% of rated current)
Refrigerant completely leaked
Check cycle
Temperature difference is ok (5-10K)
Power consumption is low (<80% of rated current)
Leakage of refrigerant or clog of cycle
Defective compressor
Temperature difference is ok (5-10K)
Power consumption is high (over rated current)
Too much refrigerant
Temperature difference is ok (5-10K)
Power consumption is in range of rated current (10%)
Normal operation
Table 38 Temperature difference and power consumption
Suction pressure Outlet temperature Reason Result
Higher than normal value Higher than normal value Defective compressor
Defective 4-way-valve
Current is low
Normal value
Too much refrigerant High pressure does not quickly
increase when compressor starts
Lower than normal value Higher than normal value Insufficient amount of refrigerant
(leakage) or clogging
Current is low
Table 39 Pressure and temperature
6 720 817 722-37.1I
Output (Ø ) No. Output state
1 2 3 4 5 6 7 8
Ø 1 ON OFF OFF OFF OFF OFF ON ON
Ø 2 ON ON ON OFF OFF OFF OFF OFF
Ø 3 OFF OFF ON ON ON OFF OFF OFF
Ø 4 OFF OFF OFF OFF ON ON ON OFF
Table 40 Pulse signal output value and valve operation