Kärcher HD 1090 Service Handbook page 19

Troubleshooting and basic settings
Unit does not run
Check pressure switch
Overflow valve disassembled
L L L
1 2 3
Pressure switch defective
– Disconnect the unit from the mains and, with
the unit switch on, measure electrical resi-
stance between the connecting terminals (in-
let-outlet). In a pressureless state, there should
be zero Ohms (contacts closed).
– If necessary, replace defective parts and reset
the pressure switch (see page 22).
Overflow valve stuck
– If the overflow valve has switched off the unit
via the pressure switch and is then stuck, the
unit will not start.
– Disassemble the overflow valve and check
whether it moves easily. If necessary, replace
defective parts.
– Lubricate all O-rings with silicone grease
6.288-080.
– Adjustment, see page 22.
17