AIRLESSCO 3A1186A Operation - Repair - Parts page 17

Problem
Clutch does not engage
3A1186A
Electrical
Cause
Pressure Control Knob
Poor Electrical Connection
Magneto
Defective Sensor
Clutch Assembly
Electrical Control Board
Solution
Ensure the pressure control knob is in the maxi-
mum clockwise position.
Remove the clutch and electrical box covers.
Check all electrical connections between the
engine magneto, sensor, control board and
clutch for loose connections or damaged leads.
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 lead (blue).
This voltage must be 13-14 VDC. If the readings
are correct, the board, sensor and magneto are
functioning. See Clutch Assembly.
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 con-
trol knob in maximum clockwise position and
prime valve open (priming), read the AC voltage
from the magneto lead to the sprayer frame. The
reading should be 19-24 VAC. If outside this
range, replace the magneto. If the magneto is
producing proper voltage, see Defective Sen-
sor.
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 read-
ing is outside standards, replace the sensor.
An alternative method of testing the sensor is to
plug a new sensor into the board to see if the
clutch will engage. When using this method,
ensure prime/pressure valve is in the prime
position because the sensor plugged into
the board in not measuring pressure in the
fluid section.
Check the spacing between the clutch field and
plate. The gap should be about .015". If the gap
is greater than .015, replace the clutch assem-
bly.
If the magneto and sensor are functioning,
replace the electrical control board.
Troubleshooting
17