AIRLESSCO SS3650 - Manual (Page 29)

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ELECTRICAL TROUBLESHOOTING
- Clutch Does Not Engage
STEP 1: Ensure that the pressure control knob (POT) is in the maximum (CW) position.
STEP 2: Remove the clutch and electrical box covers.
STEP 3: Check all electrical connections between the engine magneto, sensor, control board and clutch for loose
connections or damaged leads.
STEP 4: Disconnect the two leads from the control board (blue) and the clutch assembly (black). Using a multimeter,
with the engine at maximum RPM, pressure control knob in the maximum position and the prime valve open (priming)
position, test the DC voltage across the boards leads (blue). This voltage must be 13-14 VDC. If the readings are correct,
the board, sensor and magneto are okay and the problem is the clutch assembly. If this is the case, proceed to Step 5. If
the voltage is outside this range go to Step 7.
STEP 5: Check the spacing between the clutch field and plate. The gap should be a maximum of .010”. If the gap is
greater than .010” the gap is too wide. If this gap is too wide, replace the clutch assembly.
STEP 6: When the DC voltage from the board is not 13-14 VDC, disconnect the control board lead (black) from the
engine magneto lead (pink), located on the side of the engine. With the engine at maximum RPM (3600), pressure control
knob in maximum (CW) position and prime valve open (priming), read the AC voltage from the magneto lead to the
sprayer frame. This reading should be 19-24 VAC. If outside this range, contact your local small engine repair facility for
magneto replacement. If the magneto is producing the proper AC voltage, continue to Step 7.
STEP 7: Test the sensor by reading the resistance between the red and black wires. The resistance runs between 1.5-3K
ohms. A defective sensor usually shows no resistance (open). If the reading is outside standards, replace the sensor. An
alternative method to test the sensor, is to plug a new sensor into the board and see if the clutch will engage. Caution!
When using this method, ensure prime/pressure valve is in the prime position. This is important because the sensor
plugged into the board is not measuring pressure in the fluid section.
STEP 8: When Steps 6 & 7 have been completed and the magneto and sensor check good, the electrical control board is
the only item left, replace the board.