Check System Parameters; Electronic Expansion Valve - Bosch AHUW036A2 Service Manual

Check system parameters

5 Check system parameters
Temperature difference between inlet and outlet
depends on water flow rate and exchange-surface of the
heating system.
Symptom
No temperature difference between water inlet and outlet
Power consumption is low (<80% of rated current)
Temperature difference is ok (5-10K)
Power consumption is low (<80% of rated current)
Temperature difference is ok (5-10K)
Power consumption is high (over rated current)
Temperature difference is ok (5-10K)
Power consumption is in range of rated current (10%)
Table 38 Temperature difference and power consumption
Suction pressure
Higher than normal value
Lower than normal value
Table 39 Pressure and temperature
6

Electronic expansion valve

Fig. 34 EEV driving circuit
Output (Ø ) No.
1
Ø 1 ON
Ø 2 ON
Ø 3 OFF
Ø 4 OFF
Table 40 Pulse signal output value and valve operation
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.
36
Outlet temperature
Higher than normal value
Normal value
Higher than normal value
6 720 817 722-37.1I
2 3
OFF OFF
ON ON
OFF ON
OFF OFF
Remark
Refrigerant completely leaked
Check cycle
Leakage of refrigerant or clog of cycle
Defective compressor
Too much refrigerant
Normal operation
Reason
Defective compressor
Defective 4-way-valve
Too much refrigerant
Insufficient amount of refrigerant
(leakage) or clogging
Output state
4 5
OFF OFF
OFF OFF
ON ON
OFF ON
Result
Current is low
High pressure does not quickly
increase when compressor starts
Current is low
6 7
OFF ON
OFF OFF
OFF OFF
ON ON
Split ODU – 6 720 817 722 (2015/06)
8
ON
OFF
OFF
OFF