Repair work at the cooling system
10.5
Checking the step motor valve (-7Y3)
Spare parts:
•
Step motor valve (order no. 5025-0023)
Necessary tools
•
Crosstip screwdriver, size 2
•
Multimeter measuring device
1.
Disconnect the unit from the power supply.
2.
Remove the rear housing panel (chap. 5.3).
3.
Remove the housing cover of the lower front (chap. 5.1).
4.
Pull the electric mounting plate out of the machine room (chap. 8.5).
5.
Mark and remove the connection cables from the interface board of the step motor valve (-7N1).
6.
Measure the resistance between the black and the white connection of the step motor valve (-7Y3).
With normal am
bient temperature the resistance value should be approx. 70 Ω.
7.
Measure the resistance between the green and the red connection of the step motor valve (-7Y3). The
measuring result should not deviate by more than ± 5 % from the resistance value between the black
and the white connection.
8.
Measure the resistance between each single connection (black, white, green, red) and the valve hous-
ing. The resistance value should be infinite here.
9.
If you notice a deviation from the indicated values at one of the measurements, the step motor valve is
defective and must be replaced.
Only service personnel with specialized training as cooling technician must perform repair of
the cooling system
To avoid repair attempts by unqualified personnel, repair of the cooling system is not de-
scribed in this service manual.
Service Manual KBF (E5.2) 04-2015
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