This article covers the electrical layout and motor testing procedures for AVA Master series high-pressure washers (P60, P70, P80). These models use induction motors and a (Class I) earthed system.
Circuit Overview
The electrical system includes the following components:
- Power cord with integrated ground (earth)
- Main switch (ON/OFF)
- Capacitor (required for start phase)
- Induction motor with stator and auxiliary windings
- Micro switch (activated by water pressure via TSS)
- Grounding cable connected to motor body
These machines are earthed by design, and the ground wire must always be reconnected when servicing. The grounding cable is connected directly to the motor housing (metal chassis).
General Safety Tips
- Always disconnect the unit from power and water before any repair.
- Induction motors retain voltage for a short time — allow a brief rest before measuring.
- Verify that the ground connection is reattached before closing the machine.
- Avoid touching open terminals while capacitor is charged.
Read our article regarding Safety
Motor Testing – Resistance Values
Use a multimeter set to resistance (Ohm) mode.
The AVA Master models use two separate cables from the motor:
- One cable (with black outer sheath) goes to the switch box (main winding)
- One cable (with white outer sheath) goes to the capacitor (auxiliary winding)
Each cable contains one black and one white conductor, but their function depends on the cable:
To measure motor windings:
- Main winding: Place one multimeter probe on the black wire in the black cable, and the other on the white wire in the same cable.
- Auxiliary winding: Place one probe on the black wire in the white cable, and the other on the white wire in the same cable.
Never measure across one wire from each cable — that would measure between two separate windings and give incorrect readings.
Important: Disconnect the capacitor before performing resistance measurements. A connected capacitor will distort your readings or prevent them entirely.
Reference values (at room temperature):
Tip:
Resistance may vary slightly with temperature. Deviation of ±10% is acceptable.
If your readings are very high (over 50 Ω) or zero/∞, the winding may be open or shorted — replace the motor.
![Reference chart for resistance testing here]
Troubleshooting – Additional Electrical Components
Measuring the Capacitor Without a Capacitance Function
If your multimeter does not have a µF (capacitance) setting, you can still test the capacitor using resistance mode:
- Disconnect the capacitor completely from the system.
- Set your multimeter to Ohms (Ω).
- Place one probe on each terminal.
- You should see the resistance drop briefly (as the capacitor charges) and then rise toward ∞. This confirms the capacitor is holding charge.
- Reverse the probes and repeat — the reading should behave similarly.
If the meter shows 0 Ω continuously (shorted) or ∞ with no change (open), the capacitor is likely defective.
Replacement Advice
If a fault occurs in any part of the switch system or capacitor, it may affect nearby components. We recommend replacing the complete preassembled switch box:
Includes:
- Main switch
- Micro switch
- Capacitor
- Mounting base and fasteners
This ensures full functionality and prevents recurrence of voltage stress failures.
Pro Tip
When reinstalling the motor, ensure:
- The capacitor is reconnected in the correct orientation
- The ground wire is fixed to clean metal, using the original screw or bolt
- Cables are routed cleanly and cannot rub or pinch against the chassis
Never run an induction motor without a working capacitor — this may damage windings.
